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» 


ELEMENTS 


OF 


CHEMISTRY, 


^u    1-^.    *^.    ^yi.    C/iafita/, 

CHEVALIER    OF   THE    ORDER    OF    THE    KING,    PROFESSOR    OF    CHEM- 
ISTRY    AT     MONTPELLIER,     HONORARY     INSPECTOR     OF      THE 
MINES    OF    FRANCE,     AND    MEMBER    OF    SEVERAL    ACADE- 
MIES   OF    SCIENCES,    MEDICINE,    AGRICULTURE,    IN- 
SCRIPTIONS,   AND    BELLES    LETTRES. 


TRANSLATED  FROM  THE  FRENCH. 


C^ttlJ    amertcan  ffibttiort. 


THREZ  VOLUMES  IN  ONE. 


BOSTON : 

PRINTED    BY    J.    T.    BUCKINGHAM, 
fO^   THOMAS    Cjf   ANDREWS,    NO.   45,   NEWBU&Y-STREETo 


1806. 


-  V 


THE  great  experience  of  M.  Chaptal,  his  unaffeft^ 
ed  candour,  and  the  perfpicuity  which  is  feen  in 
every  part  of  the  following  treatife,  cannot  but  render 
it  extenfively  ufeful.  I  have  been  particularly  careful 
not  to  diminifh  this  laft  merit,  by  deviating  in  any  ret 
pe£t  from  that  fcrupulous  attention  to  accuracy  which 
is  indifpenfably  required  to  give  authority  to  the  tranf- 
lation  of  a  work  of  fcience. 

W.  NICHOLSON. 

London,  Aprilj  1791. 


CONTENTS. 


FART  FIRST. 

CONCERNIKG    THE    CHEMICAL    PRINCIPLES. 

INTRODUCTION. 

DPage 
EFINITION  of  Chemiftry  ;   its  Objea:  and  Means.— Defcrip- 
tion  of  a  Laboratory,  and  the  principal  inftruments  employed  in  che- 
mical operations,  with  a  definition  of  thofe  operations  4j 

SECTION  I. 

Concerning  the  general  law  which  tends  to  bring  the  particles  of 
bodies  together,  and  to  maintain  them  in  »  ftate  of  mixture  or  com- 
bination ^;^ 
Of  the  Affinity  of  Aggregation                                                                S3 
Of  the  Affinity  of  Corapolition                                                                54 

SECTION    II. 

Concerning  the  various  means  employed  by  chemifls  to  overcome 
the  adhefion  which  exifts  between  the  particles  of  bodies  6a 

SECTION  in. 

Concerning  the  method  of  proceeding  which  the  chemifts  ought  to 
follow  in  the  ftudy  of  the  various  bodies  prefented  to  us  by  nature    6s 

SECTION  IV. 

Concerning  Simple  or  Elementary  Subflanccs  ;o 

Chap.  1.     Concerning  Fire  71 

Art.  I.     Concerning  Calorick  and  Heat  7i 

Art.  II.     Concerning  Light  it 

Chap.  II.     Concerning  Sulphur  84 

Chap.  III.    Concerning  Carbone  87 

SECTION    V. 

Concerning  Gafes,  or  the  folution  of  certain  principles  in  Calorick 
at  the  Temperature  of  the  Atmofphere  ^        88 

Chap,  I .    Concerning  the  Hydrogenous  Gas,  or  Inflammable  Air      91 


vi  CONTENTS. 

Page 
Chap.  II.    Concerning  Oxigenous  Gas,  or  Vital  Air  96 

Chap.  III.    Concerning  Nitrogene  Gas,  Azote,  or  Atmofpherical 
Mephitis  lot 

SECTION  VI. 

Concerning  the  Mixture  of  Nitrogene  and  Oxigene  Gas  ;  or  of  at- 
mofpherick  air  109 

SECTION  VII. 

Concerning  the  combination  of  Oxigenous  Gas  and  Hydrogene, 

which  forms  Water                  ^  ixi 

Art.  I.    Concerning  Water  in  the  ft  ate  of  Ice  11% 

Art.  IT.    Concerning  Water  in  the  liquid  ftate  114 

Art.  III.    Concerning  Water  in  the  Hate  of  Gas  117 


SECTION  VIII. 

Concerning  the  combinations  of  Nitrogene  Gas.     i.  With  Hydro- 
gene  Gas.     2.  With  the  earthy  principles  forming  the  Alkalis  i«6 
Chap.  I.    Concerning  Fixed  Alka'is  lai 

Art.  I.     Concerning  the  Vegetable  Alkali,  or  Pot-afh  12a. 

Art.  II.     Concerning  the  Mineral  Alkali,  or  Soda  12  j 

Chap.  11.    Concerning  Aramoniack,  or  the  Volatile  Alkali  j»7 


SECTION  IX. 

Concerning  the  Combination  of  Oxigene  with  certain  Bales  forming 

Acids  130 

•    Chap.  I.     Concerning  the  carbonick  Acid  133 

Alt.  I.     Carbonate  of  Pot-afh  138 

Alt.  II.     Carbonate  of  Soda  139 

Art.  III.     Carbonate  of  Ammoniack  ibid 

Chap.  II.    Concerning  the  Sulphurick  Acid  I4» 

Art.  I.     Sulphate  of  Pot- aik  144 

Art.  II.    Sulphate  of  Soda  ibid 

Art,  III.    Sulphate  of  Ammoniack  145 

Chap.  III.     Concerning  the  Nitrick  Acid  146 

Art.  I.    Nitrate  of  Pot-afh  15a 

Art.  II.     Nitrate  of  Soda  155 

Art.  HI.     Nitrate  of  Ammoniack  I56 

Ch^p.  IV.     Concerning  the  Muriatick  Acid  ibid 

Art.  I.     Muriate  of  Pot-afli  16* 

Art.  11.     Muriate  of  Soda  ibid 

Art,  III.     Muriate  of  Ammoniack                 ^  165 

Chap.  V.     Concerning  the  Nitro-muriatick  Acid  167 

Chap.  VI.    Concerning  the  Acid  of  Borax  169 

Art.!.     Borate  of  Pot-a(h  «7i 

Art,  II.    Borate  of  Soda       ^  ibid 

Art.  111.    Borate  of  Ammoniack  174 


CONTENTS. 


Vll 


PART  SECOND. 

CONCERNING  LITHOLOGY  ;   OR   AN  ACCOUNT  OF   STONY  SUBSTANCES. 

Page 

Introdudion  175 

Lime  178 

Barytes,  or  Ponderous  Earth  179 

Magnefia,  or  Magnefian  Earth  180 

Aluraine,  or  pure  clay  ibid 

^ex,  or  Quartzofe  Earth,  Vitrifiable  Earth,  &c.  181 

CLASS  I. 

Concerning  the  Combination  of  Earths  with  Acids  iga 

GENUS     I. 

Earthy  Salts  with  Bafis  of  Lime  ibid 

Spec.L    Carbonate  of  Lime,  or  Calcareous  Stone  ibid 

Cryftallized  Calcareous  Stones  183 

Calcareous  Stones  which  are  not  cryftallized  184 

The  Analyfis  and  Ufes  of  Calcareous  Stone  188 

Spec.  n.    Sulphate  of  Lime,  Gypfum,  Selenite,  Plafter  Stone  191 
Spec.  III.    Fluate  of  Lime,  Vitreous  Spar,  Fufible  or  Phofphorick 

Spar,  Fluor  Spar  194 

Spec.  IV.    Nitrate  of  Lime,  Calcareous  Nitre  196 

Spec.  V.    Muriate  of  Lime,  Calcareous  Marine  Salt  197 

Spec.  VT.    Phofphate  of  Lime,  Calcareous  Phofphorick  Salt  198 

GENUS    II. 

Earthy  Salts  with  Bafe  of  Barytes  198 

Spec.L    Sulphate  of  Barytes,  Ponderous  Spar  ibid 

Spec.  II.    Carbonate  of  Barytes  aoo 

Spec.  III.    Nitrate  of  Barytes  ibid 

Spec.  IV,    Muriate  of  Barytes  ibid 

GENUS     III. 

Earthy  Salts  with  Bafis  of  Magnefia  aoi 

Spec.  I.    Sulphate  of  Magnefia,  Epfom  Salt  ibid 

Spec.  IL    Nitrate  of  Magnefia  aoa 

Spec.  III.     Muriate  of  Magnefia  ibid 

Spec.  IV.    Carbonate  of  Magnefia  ibii 


415  CONTENTS. 


GENUS   IV. 


Page 
Earthy  Salts  with  Bafe  of  Atortiine,  Alum  203 

Sped.    Sulphate  of  Alumine,  Alum  ibid 

Spec.  II.    Carbonate  of  Aiutnine  306 


GENUS     V. 

Earthy  Salts  with  Bafe  erf"  Silex  ao^ 

CLASS  H. 

Concerning  the  combination  and  Mixture  of  Primitive  Earths,  or  .  ^ 

Earthy  Mixtures.  ibid 

GENUS    I. 

Calcareous  Mixtures  ao8 

Spec.  I.    Lime-ftone  and  Magnefia  ibid 

Spec.  II.     Lime-ftone  and  Barytes  ibid 

Spec.  III.     Carbonate  of  Lime  and  Alumine  ibid 

Spec.  IV.    Lime-ftone  and  Silex  009 

Spec.V.  Lime-ftone  and  Bitumen  ibid 

Spec.  VI.    Lime-ftone  and  Iron  «r» 

GENUS    n. 

,,      Barytick  Mixtures  ibid 

"Spec.  I.     Sulphate  of  Barytes,  Petroleum,  Gypfum,  Alum,  and  Si- 
lex. — BergmanniSciagr.f  90;  Kirwan  Min.  p.  60  an 
Spec.  II.    Carbonate  of  Barytes,  Iron  and  Silex  ibid 

GENUS     III. 

Magnefian  Mixtures  ibid 

Spec.  I.    t*ure  Magnefia,  Silex,  and  Alumine  ibrd 

Spec.  II.    Carbonate  of  Magnolia,  Silex,  and  Alumine  ibid 
Spec.  III.    Pure  Magnefia  combined  witli  fomewhat  more  than  its 
Weight  of  Silex,  one  third  of  Alumine,  near  one  third  of  Water, 

and  more  or  lefs  of  Iron                                ^  213 
Spec.  IV.    Carbonate  of  Magnefia ;  Silex,  Lime,  Alumine  and  Iron  214 

Variety  I.    Afteftos  ifera 

Variety  II.     Mountain  Cork  ibM 
5pec.  V.    Carbonate  of  Magnefia  and  Lime,  Sulphurate  of  Barytes, 

Alumine  and  Iron  ^i^ 


CONTENTS,  k 


GENUS     lY. 

Page 

Aluminous  Mixtures  a  15 
Speq,  i.    Alumine,  Siiex,  Carbonate  of  Lime  and  more  or  lefs  of  Iron  ai6 

Spec.  II.     Alumine,  Silex,  Pure  Magne(k,  and  Iron  a 20 

Spec.  III.    Alumine,  Silex,  Magnelia,  Lime  and  Iron  aai 

Variety  I.    Black  Horn-ftone,  Lapis  Corneous  Nitens  Wallerii  ibid 

Variety  II.    Horn-ftone  of  a  Greenifh  Grey  colour  22% 
Spec.  IV.    Alumine,  Silex,  Carbonate  of  Magnelia,  and  of  Lime 

with  Iron  ibid 
Variety  L  Bluifh  Purple  Slate  ibid 
Variety  II.  Black  Slate  ^23 
Variety  III.  Blue  Slate  ^  ibid 
Variety  IV.  Slate  of  a  pale  white  colour  ^  ibid 
Spec.  V.  Alumine,  Silex,  Pyrites  or  fulphure  of  ^ron,  and  Car- 
bonate of  Lime  and  of  Magnelia  ^  ibid 
Spec.  VI.    Alumine,  Silex,  the  Carbonates  of  Lime  and  of  Magnefia, 

the  Sulphure  of  Iron  and  Bitumen  224 

Spec,  VII.    Alumine,  Silex,  Lime,  and  water  a»5 


GENUS     V. 

Siliceous  Mixtures  _  sa6 
Spec,  I.  Silex,  Alumine,  Lime,  and  iron,  intimately  combined  ibid 
Divifion  I.  Red  Gems,  or  precious  ftones—the  Ruby,  Garnet,  &c.  ibid 
Divifion  II.  Yellow  Gems  or  precious  ftones — the  Topaz,  the  Hy- 
acinth, &c.  337 
JDivifion  III  Green  Gems—the  Emerald,  Chryfolite,  Beryl,  &c.  aaS 
Divifion  IV.  Blue  Gems — Sapphire  _  _  230 
Spec.  II.    Silex,  fometimes  pure,  but  oftener  mixed  with  a  very 

fmall  quantity  of  Alumine,  Lime  and  iron  ibid 

Divifion  1.     Rock  Cryftal  »3i 

Variety  I.    Red  Cryftal — Falfe  Ruby  113$ 

Variety  II ,    Yellow  Cryftal — Bohemian  Topaz  ibid 

Variety  III.    Brown  Cryftal — Smoky  Topaz  ibid 

Variety  IV.     Green  Cryftal— Falfe  Emerald  Ibid 

Variety  V.     Blue  Cryftal — Water  Sapphire  ibid 

Variety  VI.   Violet  Cryftal~the  Amethyft  a34 

Diviiion  II.     Quartz  _  .  ibid 

Spec.  III.    Silex,  Alumine,  Lime,  and  iron,  intimately  mixed  ij^ 

Divifion  i.    The  Coarfer  Flints  ibid 

Diviiion  II.    The  Finer  Flints   ^  436 

Spec.  IV.    Silex,  Alumine  and  iron  '  338 

Spec.  V.     Silex,  Alumine^  Lime,  v/ith  a  fmall  portion  of  Magnefia 

and  Iron  ,  239 

Spec.  Vr.    Silex,  Lime^  Magnefia,  iron.  Coppery  and  the  Fluorick 

Acid  244 
Spec.  VII.    Silex,  the  blue  Fluate  of  Lime,  with  the  Sulphate  of 

Lime  Or  Iron  «4jf 

^ptic.VlII.    Silex,  Alumine,  Barytes,  and  Magnefia  ibi« 
B 


CONTENTS. 


CLASS  III. 

Page 


Concernin  pr  the  mixtures  of  flones  among  each  other.    Stony  Mix- 
tures.   Rocks.  2/ij 


GENUS   r. 

Rocks  formed  by  the  mixtures  of  Calcareous  ftones  with  other  fpecies  ibid 

Spec.  I.    Carbonate  of  Lime,  and  Sulphate  of  Barytes  ibid 

Spec.  TL    Carbonate  of  Lime  and  Mica  ibid 

Spec.  JIL     Mixtures  of  Calcareous  and  Magnefian  flones  248 

Spec.  IV.    Calcareous  Stones,  and  Fragments  of  Quartz  ibid 

GENUS    II. 

Compound  ftones  formed  by  the  Mixture  of  Barytick  flones  with 

other  flones                                                                         '  ibid 
Spec.  L    Ponderous  Spar  mixed  with  a  fmall  quantity  of  Calcareous 

Spar  ibid 

Spec.  II.     Ponderous  fpar  and  ferpentine  249 

Spec.  III.     Ponderous  fpar  and  Fluor  fpar  ibid 

Spec.  IV.    Ponderous  fpar  and  indurated  clay  ibid 

■  Spec.  V.    Ponderous  fpar  and  quartz  ibid 

Spec.  VL     Ponderous  fpar  and  lava  ibid 


Rocks  or  flones  formed  by  the  mixture  of  magnefian  flones  with 

other  kinds  250 

Spec.  1.    Magnefian  flones  mixed  together  ibid 

Spec.  II.     Magnefian  flones  and  calcareous  flones  ibid 

Spec.  HI.    Magnefian  flones  and  aluminous  flones  ibid 

Spec.  IV.    Magnefian  flones  and  filiceous  flones  ibid 

GENUS    IV. 

P,.ocks  or  Stones  formed  by  the  mixtures  of  aluminous  Hones  with 

other  fpecies                  ^  251 

Spec.  I.     Sehiflus  and  Mica  ibid 

Spec.  11.     Sehiflus  and  Garnet  ibid 

Spec.  in.    Schillus,  Mica  and  Quartz  mixed  in  fmall  fragments  ibid 

Spec.  TV.    Schiftus  and  Schorl  25  z 

Sp«c.  V.    Clay  and  Quartz  ibid 

GENUS    r. 

Compound  Stones  formed  by  the  Mixture  and  of  Re  tTnion  of 

Quartzofe  flones  with  each  other  253 

Spec.  I.  Qo^rtz  and  Schorl  ibid 

Spec.  II,    Quartz  and  Feld  Spar  ibid 

Spec.  in.     Grit-flone  and  Gitrnct  ibid 


CONTENTS.  3.1 

Page 

Spec.  !V»    Quartz,  Feld  Spar,  and  Scliorl         ^  a54 

Spec.  V.     Fragments  of  Quartz  united  by  a  Siliceous  Cement  ibid 

Spec.  VI.     Jafper  and  Feld  Spar  ibid 

Spec.  VII.    Jafper  and  Garnet  ajj 

Spec.  VIII.    Jafper  and  Calcedony  ibid 

Spec.  IX.     Jafper  and  Quartz  256 

Spec.  X.     Jafper,  Quartz,  and  Feld  Spar  ibid 

Spec.  XI.    Schorl,  Garnet,  and  Tourmaline  ibid 


CENUS    VI. 

S«per-compound  flones,  or  fuch  as  refult  from  the  Mixture  and  Re 

union  of  feveral  different  Genera  ibid 

Spec.  I.     Petrofilex,  Alumine,  and  Calcareous  Spar  ibid 

Spec.  II.     Clay,  Steatites,  and  Calcareous  Spar  257 

Spec.  in.     Clay,  Zeolite,  Schorl,  and  Calcareous  Spar  ibid 

Spec  ~V.     Clay,  ferpentine  and  calcareous  fpar  ibid 

Spec.  V.     Serpentine,  Mica,  and  Calcareous  Spar  ibid 

Spec.  VI.    Serpentine,  Schorl,  and  Calcareous  Stone  ibid 

Spec.  VII.     Steatites,  Mica,  and  Garnets  ibid 

Spec.  VIII.     Steatites,  Mica,  ahJ  Schorl  ibid 

Spec.  IX.     Garnets,  Quartz,  Mica,  and  Serpentine  ibid 

Spec.  X.     Feld  Spar,  Quartz,  Mica,  Steatites  258 

Spec.  XI.     Quartz,  Mica,  and  Clay  ibid 

Spec.  Xn.     Quartz,  Clay  and  Steatites  ibid 

Concerning  the  Diamond  ibid 

General  Views  refpefting  the  Decompofition  and  Changes  to  which 

the  Stony  part  of  our  Globe  has  been  fubjedled  a6i 


PART  THIRD. 

CONCERNING     METALUCK    SUBSTANCES.. 


Introdudllon           ^               ^  ^71 

Chap.  I.    Concerning  Arfenick  284 

Chap.  IL     Concerning  Cobalt  a88 

Chap.  III.     Concerning  Nickel  aoi 

Chap.  IV.    Concerning  Bifmuth  a^-j 

Chap.  V.    Concerning  Antimony  ^95 

Chap.  VI.    Concerning  Zinc  30^ 

Chap.  VII.     Concerning  Manganefe  31^ 

Chap.  VIII.     Concerning  Lead  315 

Chap.  IX.     Concerning  Tin  324 

Chap.  X.     Concerning  Iron  ^^j. 
Art.  I.    Concerning  Iron  Ores  which  are  attracted  by  the  Magnet 
Art.  II.    Concerning  Sulphureous  Iron  Ores,  or  the  Sulphures  of 


Iron 


332 
33S 


xii  CONTENT^. 

Bag£ 
Art.  III.    Concerning  the  Spathofe  Iron  Ores,  or  Carbonates  of 

Iron  33^ 
Art.  IV.    Concerning  the  Bog  Ores  of  Iron,  or  Argillaceous  Iron 

Ores  33* 

Art.  V.     Concerning  native  Pruflian  Blue,  or  the  Pruffiate  of  iron  ^39 

Art.  VI,    ConcerningPlumbago,  or  theCarbure'of  iron  ibid 

Chap.  XI.    Concerning  Copper  35 S 

Chap.  XII.   Concerning  Mercury  368 

Chap.  XIII.     Concerning  Silver  378 

Chap.  XIV.    Concerning  Gold  384 

Chap.  XV.     Concerning  Platina  393 

Chap.  XVI.    Concerning  Tungften  and  Wolfram  398 

Art.  I.    Concerning  Tungften  ibid 

Art.  II.     Concerning  Wolfram  401 

Chap.  XVII.    Concerning  Molybdena  404 


PART  FOURTH. 

CONCERNING  VEGETABLE  SUBSTANCES. 


Iatrodu(5tioii  409 
SECTION  lo 

Concerning  the  Struflure  of  Vegetables  413 

Art.  I.    Concerning  the  Bark  ibid 

Art.  II.    Concerning  the  Ligneous  Te^^ture  415 

Art.  III.     Concerning  the  VefTeJs  416 

Art.  IV,    Concerning  the  Glands  417 

SECTION  II. 

Concerning  the  Nutritive  Principles  of  Vegetables  ibid 

Alt.  I.     Concerning  Water,  as  a  Nutritive  Principle  of  PlantSf  418 

Art.  II.  Concerning  Earth  and  its  irafiuence  in  vegetation  420 
Art.  III.  Concerning  Nitrogenous  Gas,  as  a  Nutritive  Prinicple  of 

Plants  \  ^  4za 
Art.  IV.    Concerning  the  Carbonick  Acid,  as  a  Nutritive  Principle 

of  Vegetables  ^  '4^3 

Alt.  V.    Concerning  Light,  and  its  influence  on  Vegetation  ibiq 

SECTION  III. 

^kmcerning  the  H^fults  of  Nutrition,  or  the  Vegetable  Principles  445 

Art.  I.    Concerning  Mucilage  ibid 

Art.  II.     Concerning  Oils  417 

Pivifion  I.    Concerning  Fixed  Oils  428 

Divifion  II.     Concerning  Volatile  Oils  434 

Concerning  Camphor  438 

Ais^.111-    Concerning  Refins  441 


CONTENTS»  xiiji 


Art.  IV.    Concerning  Balfams 
Art.  V.    Concerning  Gum  Refins 

Concerning  Caoutchouc,  or  Elaftick  Gum 

Concerning  Varniih 
Art.  VI.     Concerning  the  Feciila  of  Vegetables 
Art.  VII.    Concerning  the  Vegetable  Gluten 
Art.  VIII.     Concerning  Sugar 
Art.  IX.    Concerning  the  Vegetable  Acids 
Art.  X.    Concerning  Alkalis 
Art.  XI.     Concerning  the  Colouring  Principles 
Art.  XII.    Concerning  the  Pollen,  or  Fecundating  Powder  of  the 

Stamina  of  Vegetables* 

Concerning  Wax 
Art.  XIII.    Concerning  Honey 

Art.  XIV.     Concerning  the  Ligneous  Part  of  Vegetables 
Art.  XV.     Concerning  other  Fixed  Principles  of  the  Vegetable 

Kingdom 
Art.  XVI.    Of  the  Common  Juices  extraded  by  incifion  or  ex- 

preffion 

Concerning  the  Juices  extracted  by  incifion 

Concerning  Vegetable  Juices  extraded  by  Prefliire 


SECTION  IV. 

Concerning  fuch  Principles  as  efcape  from  Vegetables  by  Tranfpl- 

ration  4^5 

Art.  I.    Concerning  Oxigenous  Gas,  afforded  by  Vegetables  ibid 

Art.  II.     Concerning  the  Water  afforded  by  Vegetables  497 

Art,  III.     Concerning  the  Aroma,  or  Spiritiis  Re(5tor  ibid 


SECTION   V. 

Concerning  the  alterations  to  which  Vegetables  are  fubjetft  after 

they  are  deprived  of  life  500 
Chap.  1.  Concerning  the  aftion  of  Heat  upon  Vegetable  Subftances  ibid 
Chap.  II.     Concerning  the  adion  of  Water  fingly  applied  to  Veget- 
able Subftances  504 
Concerning  Fit-coal  507 
Concerning  Volcanos  5 1 1 
Chap.  III.    Concerning  the  decompofition  of  vegetables  in  the  bow- 
els of  the  earth  517 
Chap.  IV.     Concerning  the  action  of  air  and  heat  upon  vegetables  518 
Chap.  V.    Concerning  the  a^ion  of  air  and  water,  which  determine 
a    commencement  of  fermentation    that  feparates  the  vegeta- 
able  juices  from  the  hgneous  part  5I5 
Chap.  VI.    Concerning  the  adlion  of  air,  of  heat,  and  of  water  upon 

vegetables  52  j 

Art.  I.    Concerning  the  Spirituous  Fermentation  and  its  produds  jai 

Concerning  Tartar  ^  ^^S 

Art.  II.    Concerning  the  Acid  Fermentation  ^-^ 

Art.  Ill,    Conceroin^  the  Putrid  Fermentation  537 


xiv  CONTENTS. 

PART  FIFTH. 

CONCERNING    ANIMAL    SUBSTANCES. 

.  Page 

Introdudlion  5  40 

Chap.  I.     Concerning  DIgeftion  543 

Chap.ir.     Concerning  Miik                                  •  545 

Chap.  III.     Concerning  the  Blood  551 

Chap.  IV.    Concerning  Fat  554 

Chap.  V.    Concerning  the  Bile  ^'^y 

Chap.  VI.    Concerning  the  Soft  and  White  Parts  of  Animals  560 

Chap.  VII.    Concerning  the  Mufcular  or  Fiefhy  Parts  564 

Chap.  VIII.     Concerning  Urine  566 

Concerning  the  Calculus  of  the  Bladder  571 

Chap.  IX.  Concerning  Phofphorus  574 
Chap.  X.    Concerning  certain  Subftances  obtained  from  Animals 

for  theufe  of  medicine  and  the  arts  583 

Art*  !•  Concerning  the  Produifts  afforded  by  Quadrupeds  584 
Art.  II.    Concerning  certain  Produfts  afforded  by  Fifhes              '        586 

Art.  Ilf.     Concerning  certain  produds  afforded  by  Birds  587 

Art.  rv.  Concerning  certain  produds  afforded  by  Infers  588 
Chap.  Xf.    Concerning  fome  other  Acids  extraded  from  the  Animal 

Kingdom  59z 

Chap.  Xil.     Concerning  Patrefadipn  595 

Concerning  Mineral  Waters  6«j| 


NOTICE    TO     BOOKBINDERS. 

Signature  3...T  follows  immediately  after  3...R. 


Advertisement  of  the  Author. 


Agriculture  is,  no  doubt,  the  bafis  of  pubiick 

xv-elfare,  becaufe  \t  alone  fupplies  all  the  wants  which  nature 
has  connected  with  our  exiftence.  But  the  arts  and  commerce 
form  the  glory,  the  ornament,  and  the  riches  of  every  polilhed 
nation  ;  fince  our  refinement,  and  mutual  dependence  on  each 
other,  have  created  a  new  fet  of  wants  which  require  to  befup- 
plled.  The  cultivation  of  the  arts  is  therefore  become  almofl  as 
neceffarv  as  that  of  the  ground  ;  and  the  true  means  of  fecuring 
thefe  two  foundations  of  the  reputation  and  profperity  of  a  ftate, 
confiil  in  encouraging  the  fcience  of  Chemiftry,  which  difcovers 
their  principles.  If  this  truth  were  not  uniferfally  acknowledg- 
ed, I  might  on  the  prefent  occafion  give  an  account  of  the  fuc- 
cefs  with  which  my  labours  have  been  attended  in  this  prov- 
ince.* I  might  even  call  upon  the  pubiick  voice  ;  and  it  would 
declare  that,  fmce  the  ellabliihment  of  lectures  on  chemiflry, 
between  three  and  four  hundred  perfons  have  every  year  derived 
advantage  from  inftru£l:ions  in  this  fcience.  It  is  well  known 
that  our  ancient  fchools  of  medicine  and  furgery,  whofe  fuccefs 
and  fplendour  are  connected  with  the  general  Intereffc  of  this 
province,  are  more  flourifhing  and  more  numerous  fince  that 
period.  And  with  the  fame  confidence  I  might  appeal  to  the 
pubiick, that  our  manufactures  are  daily  increafing  in  perfeflion; 
that  feveral  new  kinds  of  induUry  have  been  introduced  into 
Languedoc  ;  that,  in  a  regular  fucceflion,  abufes  have  been  re- 
formed in  the  manufaftories,  while  the  procefles  of  the  arts  have 
been  fimplified  ;  that  the  number  of  coal  mines  a6luaily 
wrought  is  increafed  ;  and  that,  upon  my  principles,  and  in  con- 
fequence  of  my  care  and  attention,  manufactories  of  alum,  of  oil 
of  vitriol,  of  copperas,  of  brown  red,  of  artificial  pozzolaua,  of 
cerufe,  of  white  lead,  and  others,  have  been  eftablilhed  in  fever- 
al parts  of  the  province. 

Chemiftry  is  therefore  efientialfy  coJineCled  with  the  reputa- 
tion and  profperity  of  a  {late  j  and  at  this  peculiar  inllant,  when 

*  Languedoc, 


i6         ADVERTISEMENT  OF  THE  AUTHOR. 

the  minds  of  men  are  univerfally  bufied  in  fecuringfthe  publick 
welfare,  every  citizen  is  accountable  to  his  country  for  all  the 
good  which  his  peculiar  fituation  permits  him  to  do.  Every 
one  ought  to  haftcn,  and  prefent  to  fociety  the  tribute  of  thofe 
talents  which  heaven  has  beftowcd  on  him  ;  and  there  is  no  one 
who  is  not  able  to  bring  fome  materials,  and  depofite  them  at 
the  foot  of  the  fuperb .  edifice  which  the  virtuous  adminiftrators 
are  raifing  for  the  welfare  of  the  whole.  It  is  with  thefc  views 
that  I  have  prefumed  to  offer  to  my  countrymen  the  vi'ork  which 
I  at  prefent  publifli  ;  and  1  entreat  them  to  exercife  their  feveri- 
ty  upon  the  intention  of  the  author  only,  but  to  referve  all  their 
indulgence  to  the  work. 

I  publifli  thefe  elements  of  Chemiftry  with  the  greater  confi- 
dence, becaufe  I  have  had  opportunities  myfelf  of  obferving  the 
numerous  applications  of  the  principles  which  conftitute  its 
bafis  to  the  phenomena  of  nature  and  art.  The  immcnfc  eftab- 
lifiiment  of  chemical  produdls  which  I  have  formed  at  Mont- 
pellier,  has  allowed  me  to  purfue  the  developement  of  this  doc- 
trine, and  to  obferve  its  agreement  with  all  the  fa£ls  which  the 
various  operations  prefent  to  us.  It  is  this  doftrine  alone 
which  has  led  me  to  fimplify  mofl:  of  the  proceffes,  to  bring 
fome  of  them  to  perfection,  and  to  reClify  all  my  ideas.  It  is 
therefore  with  the  moft  intimate  confidence  that  I  propofe  it. 
i  find  no  difficulty  in  making  a  publick  a«knowledgment  that  I 
have  for  fome  time  taught  a  different  do£lrine  from  that  which 
I  at  prefent  offer.  I  then  believed  it  to  be  true  and  folid  ;  but 
I  did  not  on  that  account  ceafe  to  confult  nature.  I  have  con- 
llantly  entered  into  this  refearch  with  a  mind  eager  for  improve- 
ment. Natural  truths  were  capable  of  fixing  themlelves  with 
all  their  purity  in  my  mind,  becaufe  I  hadbanifhed  prejudice  ; 
and  infenfibly  I  found  myfelf  drawn  by  the  force  of  facls  to  the 
do6lrine  I  now  teach.  Let  other  principles  imprefs  the  fame 
conviction  on  my  mind  •,  let  the  fame  number  of  phenomena 
and  fa£ts  exhibit  themfelves  in  their  favour  ;  the  fame  number 
of  happy  applications  to  the  operations  of  nature  and  of  art ; 
let  them  appear  to  iny  mind  with  all  the  facred  characters  of 
truth  ;  and  I  will  pttblilh  them  with  the  fame  zeal  ;  and  with 
the  fame  intereft.  I  condemn  equally  the  man  who,  at- 
tached to  the  ancient  notions,  refpeCls  them  fo  miich  as  to  re- 
ject without  mature  examination  every  thing  which  appears  to 
oppofe  them  ;  and  him  who  embraces  with  enthufiafm,  and  al- 
moil  without  reflection,  the  principles  of  any  new  doCtrine. 
Both  are  worthy  of  compaffion  if  they  grow  old  in  their  preja-^ 
slices  -y  and  both  are  worthy  of  blame  if  they  perpetuate  them. 


ADVEkTISEMENT  OF  THE  AUTHOR.         17 

I  have  been  careful  to  banifli  all  difcuffions  from  my  work. 
That  fpirit  of  party  which  but  too  often  caufes  a  divifion  between 
perfons  who  are  putfuing  the  fame  objects,  that  tone  of  bitter- 
nefs  which  predominates  in  certain  difputes,  that  want  of  can- 
dour which  is  infenfibly  produced  by  the  movements  of  felf-Iove, 
have  but  too  long  retarded  the  progrefs  of  our  knowledge.  The 
love  of  truth  is  the  only  paflion  which  a  philofopher  ought  to 
indulge.  The  fame  objeft,  the  fame  intereft,  tend  to  unite 
themifts.  Let  the  fame  fpirit  infpire  them,  and  dire£l;  all  their 
labours.  Then  we  (hall  foon  behold  chemiftry  advancing  in  ^ 
rapid  progrefs  •,  and  its  cultivators  will  be  honoured  with  the 
fuffrage  and  the  gratitude  of  their  countrymen. 

I  have  endeavoured  in  this  work  to  explain  my  ideas  with 
clearncfs,  precifion,  and  method.  I  know  by  experience  that 
the  fuccefs  of  any  work,  and  its  various  degrees  of  utility,  often 
depend  on  the  form  under  which  the  dodlrine  which  it  contains 
is  difplayed  ;  and  it  has  accordingly  been  my  intention  to  fpare 
no  pains  in  exhibiting  the  truths  which  form  the  bafis  of  this 
v/ork  in  all  the  charadlers  they  are  juflly  entitled  to. 

In  compofing  thefe  elements  of  chemiftry,  I  have  availed  my- 
felf  with  advantage  of  all  the  fa£l:s  which  I  have  found  in  the 
"works  of  the  celebrated  chemifts  who  adorn  this  age.  I  have 
even  made  no  fcruple  to  follow  their  method  in  drawing  up 
certain  articles  j  and  have  transferred  into  my  own  work,  al- 
moft  without  alteration,  thofe  fadls  which  I  have  elfew^cre 
found  defcribed  with  a  greater  degree  of  precifion  and  perfpi- 
cuity  than  I  might  have  been  capable  ©f  bellowing  on  them. 
This  proceeding,  in  riiy  opinion,  renders  homage  to  authors  in- 
(lead  of  robbing  them.  If  fuch  a  proceeding  might  juftify  re- 
clamations, INIeflrs.  Lavoifier,  De  Morvcau,  Berthollet,  De 
Fourcroy,  Sage,  Kirwan,  &c.  might  eafily  declare  againft  me. 

I  v/as  well  aware  that  the  pretenfion  of  knowing,  difcufling, 
and  methodically  dillributing  the  whole  of  our  prefent  fcience 
of  chemiftry,  was  an  enterprize  beyond  my  ability.  This  fci- 
ence has  made  fo  great  a  progrefs,  and  its  applications  are  fo 
tnultiplied,  that  it  is  impolfible  to  attend  to  the  whole  with  the 
iame  care  ;  and  it  appears  to  me  that  the  writer  of  an  eleruen- 
tary  work  ought  at  [Tfefent  to  attend  principally  to  the  developc- 
rr.ent  of  general  principles,  and  content  himfelf  in  pointing  out 
the  confequences,  and  their  applications.  In  this  way  of  pro- 
ceeding we  fliall  follow  the  method  which  has  long  been  prac- 
tifed,  in  the  (tudy  of  the  mathematicks  j  the  principles  of  which, 
nearly  infulated,  and  feparated  from  all  application,  form  the 
firit  fluilv  of  him  who  means  to  acquire  them. 
C 


18         ADVERTISEMENT  OF  THE  AUTHOR, 

To  obtain  a  thorough  acquaintance  with  all  the  knowledge 
which  has  been  acquired  in  chemiftry  until  our  time,  the  chem- 
iail  part  of  the  Encyclopedie  Methodlque  may  be  confulted. 
-In  this  work  the  celebrated  author  gives  the  molt  intcrefling  ac- 
count of  the  progrefs  of  the  fcience.  Here  it  is  that  he  difcufT- 
cs  the  feveral  opinions  with  that  candour  and  energy -which  be- 
come the  man  of  letters,  whofe  mind  is  dire6led  to  truth  only. 
Here  it  is  that  he  has  made  a  precious  depofite  of  all  the  knowl- 
edge yet  acquired,  in  order  to  prefent  to  us  in  the  fame  point 
of  view  all  which  has  been  done,  and  all  which  remains  to  be 
done  :  and  here,  in  a  word,  it  is  that  Mr.  De  Morveau  has  ren- 
dered the  moft  (triking  homage  to  the  truth  of  the  do^lrine  we 
now  teach  ;  becaufe,  after  having  combated  fome  of  its  princi- 
ples in  the  firft  volume,  he  has  had  the  courage  to  recant,  the 
moment  the  fa£ls  feen  in  abetter  point  of  view,  and  repeated 
experiments,  had  fufEciently  enlightened  him.  This  great  ex- 
ample of  courage  and  candour  is  doubtlefs  honourable  to  the 
learned  man  who  gives  it  ;  but  it  cannot  fail  to  add  ftill  more 
to  the  confidence  which  may  be  placed  in  the  dodlrine  which  is 
ifsobje^l. 

The  developement  of  the  principles  upon  which  the  New 
Nomenclature  is  efta'blifhed,  may  be  found  in  the  Elementary 
Trcatife  of  Chemiftry  of  Mr.  Lavoifier  ;  and  I  refer  likewife  to 
this  excellent  work  for  the  figure  and  explanation  of  all  the  ap- 
paratus I  fhallhave  occafion  to  fpeak  of.  I  take  this  ftep  the 
more  earnedly,  becaufe,  by  aflbciating  my  own  produftions  to 
thofe  of  this  celebrated  chemift,  I  entertain  the  hopcbf  feouring 
their  fuccefs,  and  can  deliver  them  into  the  hands  of  the  publick 
-with  the  greater  confidence. 


preliminary  Discourse* 


IT  appears  that  the  ancient  nations  pofreiFed  fome  no- 
-tions  of  chemiftry.  The  art  of  working  metals,  which  dates 
from  the  moft  remote  antiquity  j  the  luftre  which  the  Phoeni- 
cians gave  to  certain  colours  j  the  luxury  of  Tyre  ;  the  numer- 
ous manufactures  which  that  opulent  city  included  within  its 
walls — all  announce  a  degree  of  perfection  in  the  arts,  and  fup- 
pofe  a  confiderable  extent  and  variety  of  chemical  knowledge. 
But  the  principles  of  this  fcience  were  not  then  united  into  a 
body  of  dodlrine  ;  they  were  concentrated  in  the  worklhops  of 
the  manufa£lures,  where  they  had  their  origin  :  and  obferva- 
tions  alone,  tranfmitted  from  one  operator  to  another,  enlighten- 
ed and  condu(fi:ed  jhe  fteps  of  the  artifts.  Such,  no  doubt,  has 
been  the  origin  of  all  the  fciences.  At  firll  they  prefented  un- 
connefted  fa<Sls  ;  truths  were  confounded  with  errour  ;  time 
tand  genius  alone  could  clear  up  the  confnfion  j  and  the  pro- 
^refs  of  information  is  always  the  fruit  of  flow  and  painful  ex- 
periment. It  is  difficult  to  point  out  the  precife  epocha  of  the 
origin  of  chemical  fcience  j  but  w^  find  traces  of  its  exiftence 
in  the  molt  remote  ages.  Agriculture,  mineralogy,  and  all  the 
arts  which  are  indebted  to  it  for  their  principles,  were  cultivated 
and  enlightened.  We  behold  the  original  nations,  immediately 
:fucceeding  the  fabulous  ages,  furrounded  by  all  the  arts  "which 
fupplied  their  wants  ;  and  we  may  compare  chemiilry  to  that 
famous  river,  whofe  waters  fertilize  the  lands  they  inundate,  but 
whofe  fources  are  Hill  to  us  unknown. 

Egypt,  which  appears  to  have  been  the  nurfe  of  chemiftry,  re- 
.duced  to  principles,  was  not  flow  in  turning  the  applications  of 
.this  fcience  towards  a  chimerical  end.  The  firft  feeds  of  chem- 
iftry were  foon  changed  by  the  paffion  of  making  gold.  In  a 
moment  all  the  labours  of  operators  were  diredled  towards  al- 
-chemy  alone  ;  the  great  objcti  of  ftudy  became  fixed  on  an  en- 
deavour to  interpret  fables,  allufions,  hieroglyphicks;^  Tv  c.  ;  and 
the  induftry  of  feveral  centuries  was  confecrated  to  the  enquiry- 
after  the  philofopher's  ftone.  '  But  thougii  we  admit  that  the 
alchemiits  have  retarded  the  progrefs  of  chemiilry,  we  are  very 
i"4ir  frombeini^  diipofed  to  any  outrage  on  the  memory  of  the& 


20  PRELIMINARY   DISCOURSE. 

philofophers  *,  we  allow  them  the  tribute  of  efteem  to  which  on 
io  many  accounts  they  are  entitled.  The  purity  of  their  fenti> 
inents,  the  fimpiicity  of  their  manners,  their  fubmiffion  to  Prov- 
idence, and  their  love  for  the  Creator,  penetrate  with  veneration 
all  thofe  who  read  their  works.  The  profoundeft  views  of  ge- 
nius are  every  where  feep  in  their  writings,  allied  with  the  moft 
extravagant  ideas.  The  moft  fublime  truths  are  degraded  by  ap- 
plications of  the  moft  ridiculous  nature  ;  and  this  aftonifhing 
contraft  of  fuperftition  and  philofophy,  of  light  and  darknefs, 
compels  us  to  admire  them,  even  at  the  inftant  that  we  cannot 
withold  our  cenfure.  We  muft  not  confound  the  fe£l  of  al- 
chemifhs,  of  whom  we  (hall  proceed  to  fpeak,  with  that  crowd 
of  impoftors,  that  fordid  multitude  of  operators  at  the  furnace, 
whofe  refearches  were  direded  to  the  difcovery  of  minds  capa- 
ble of  being  impofed  upon,  who  fed  the  ambition  of  fuch  weak 
minds  by  the  deceitful  hope  of  increafing  thek  riches.  This 
laft  clafs  of  vile  and  ignorant  men  has  never  been  acknowledged 
by  the  true  alchemifts  ;  and  they  are  no  more  entitled  to  that 
name,  than  the  vender  pf  fpegificks  on  theftage  to  the  honoura- 
ble name  of  Phyfician. 

The  hope  of  the  alchcmift  may  indeed  be  founded  on  a  flen- 
der  bafis  5  but  the  great  man,  the  man  of  genius,  even  at  the 
time  when  he  is  purfuing  an  imaginary  obje£t,  knows  how  to 
profit  by  the  phenomena  which  may  prefent  therafelves,  and  de- 
rives from  his  labours  many  ufeful  truths,  which  would  efcapc 
the  penetration  of  ordinary  men.  Thus  it  is  that  the  alchemifts 
have  fucceftively  enriched  pharmacy  and  the  arts  with  moft  of 
their  compofitions.  The  ftrong  defire  of  acquiring  riches  has 
in  all  times  been  a  paffion  fo  general,  that  this  fingie  motive  has 
been  fufficient  to  lead  many  perfons  to  the  cultivation  of  a  fci- 
ence  which  has  more  relation  than  any  other  to  metals  ;  which 
iludies  their  nature  more  particularly,  and  appears  to  facilitate 
the  means  of  compofmg  them.  It  is  known  that  the  Abdarites 
did  not  begin  to  confider  the  fciences  as  an  occupation  worthy 
a  reafonable  man,  until  they  had  fcen  a  celebrated  philofopher 
enrich  himfelf  by  fpeculations  of  commerce  :  and  I  do  not  doubt 
hut  that  the  defire  of  making  gold  has  decided  the  vocation  of 
feveral  chemifts.  We  are  therefore  indebted  to  alchemy  for 
ieveral  truths,  and  for  feveral  chemical  profeiTors  :  but  this  ob- 
ligation is  fmall  in  comparifon  to  the  mafs  of  ufeful  truth  whicli 
might  have  been  afforded  during  the  coUrfe  of  feveral  centuries  ; 
if,  inftead  of  endeavouring  to  form  the  metals,  the  operations  of 
^hemifts  had  been  confined  to  anaiyfing  them,  fimpiifying  the 
means  of  extra£ling  them,  combining  them  together,  working 
^hern,  and  multiplying  and  rectifying  their  ufea. 


PRELIMINARY   DISCOURSE.  ir 

The  rage  for  making  gold  was  fucceedotl  by  the  feduclive 
hope  of  prolonging  life  by  means  of  chemiftry.  The  pcrfuar 
fuafidn  was  eafily  admitted,  that  a  fcience  which  affords  reme^ 
dies  for  all  diforders  might  without  effort  fucceed  in  affording 
a  univerfal  medicine.  The  relations  which  have  been  handed 
down  to  us  of  the  long  life  of  the  ancients,  appeared  to  be  a 
natural  effedl  of  their  knowledge  in  chemiflry. '  The  numer- 
ous fables  of  antiquity  obtained  the  favour  of  being  admitted 
among  eftablifhed  fa£ls  ;  and  the  alchemifts,  after  having  ex- 
haufted  themfelves  in  the  fearch  after  the  philofopher's  ftone, 
appeared  to  redouble  their  efforts  to  arrive  at  an  objecft  flill 
more  chimerical.  At  this  period  the  elixirs  of  life,  the  arcana, 
the  polychrefl  medicines,  had  their  origin  :  together  with  all 
thofe  monftrous  preparations,  of  which  a  few  have  been  handed 
down  even  to  our  days. 

The  chimera  of  the  univerfal  medicme  agitated  the  minds  o£ 
moft  men  in  the  fixteenth  century  ;  and  immortality  was  then 
promifed  with  the  fame  effrontery  as  a  charlatan  now  announ- 
ces his  remedy  for  every  difeafe.  The  people  are  eafily  feduced 
by  thefe  ridiculous  promifes  ;  but  the  man  of  knowledge  can 
jiever  be  led  to  think  that  chemiftry  can  fucceed  in  reverfing 
the  general  law  of  nature,  which  condemns  all  living  beings  to 
renovation,  and  a  continual  circulation  of  decompofitlons  and 
fuccefTive  generations.  This  fa6f  gradually  became  an  objedl  o£ 
contempt.  The  enthufiaft  Paracelfus,  who  after  having  flatter- 
ed himfeJf  with  immortality,  died  at  the  age  of  forty-eight,  at 
^  inn  at  Saltfburg,  completed  its  difgrace. — From  that  mo- 
ment the  fcattered  remains  of  this  fe£t  united  themfelves 
never  more  to  appear  again  in  publick.  The  light^  which  be- 
gan to  fhine  forth  on  all  fides,  rendered  it  neceiTary  that  they 
ihould  have  recourfe  to  fecrecy  and  obfcurity  j,  and  thus  at 
length  chemiftry  became  purified. 

James  Earner,  Bohnius,  Tachenlus,  Kunckel,  Boyle,  Crol- 
)Ius,  Glafer,  Glauber,  Schroder,  &c.  appeared  on  the  ruins  of 
thefe  two  fedts,  to  examine  this  indigelted  aggregate,  and  fep- 
arate  from  the  confufed  mafs  of  phenomena,  of  truth  and  o£ 
errour,  every  thing  Vv'hich  could  tend  to  enlighten  the  fcience. 
The  fe(fl  of  the  adepts,  urged  on  by  the  madnefs  of  immortali- 
ty, had  difcovered  many  remedies  j  and  pharmacy  and  the  arts 
then  became  enriched  with  formulae  and  compofitions,  whofc 
operations  required  only  to  be  rectified,  and  their  applications 
better  eftimated. 

Nearly  at  the  fame  time  appeared  the  celebrated  Becher- 
Ke  withdrew  chemiftry  from  the  too  narrow  limits  of  phar- 
Sfnr.cy.     He  fhewed  its   conive^ion  with  all  the  phenomena  of 


S2  PRELIMNARY  DISCOURSE. 

nature  ;  and  the  theory  of  the  formution  of  metals,  the  pheno- 
mena of  fermentation,  the  laws  of  putrefa61;it)»^  v/exc  all  com- 
prehended and  developed  by  this  fuperiour  genius.  GhemHtryr 
was  then. directed  to  its  true  object :  and  Stahl,  who  fucceed- 
«d  Becher,  reduced  to  certain  general  principles  all  the  fact*! 
with  which  his  predeccfTor  had  enriched  the  fcicnce.  He 
fpoke  a  language  lefs  enigmatical  ;  he  clafled  all  the  fafts  with, 
order  and  method  ;  an^  purged  the  fcience  of  that  alchemick 
infe£lion,  to  which  Becher  himfelf  was  too  much  attached. 
But  if  we  confider  how  great  are  the  claims  of  Stahl,  and  how 
few  the  additions  which  have  been  made  to  his  docElrine  until 
the  middle  of  this  century,  v/e  cannot  but  be  aftoniflied  at  the 
fmall  progrefs  of  the  fcience.  When  we  confult  thir  labours  of 
the  chemifts  who  hare  appeared  fince  the  time  of  Stahl,  we 
fee  moft  of  them  chained  down  to  the  fteps  of  this  great  maa, 
$)lindly  fubfcribing  to  all  his  ideas  ;  and  the  labour  of  think- 
ing appeared  no  longfer  to  exift  among  them.  Whenever  a 
well  made  experiment  threw  a  gleam  of  light  unfavourable  to 
his  doctrine,  we  fee  thera  torment  themfelves  in  a  ridiculous 
snanner  to  form  a  delufive  interi:>retation.  Thus  it  was  that 
the  increafe  of  weight  which  metals  acqwire  by  calcination, 
though  little  favourable  to  the  idea  of  the  fubtraclion  of  a  prin- 
ciple without  any  other  addition,  was  neverthelefs  incapable  of 
injuring  this  dotlrine. 

The  almoU  religious  opinion  which  en^aved  all  the  chemifts 
to  Stahl,  has  no  doubt  been  pernicious  to  the  progrefs  of  chenb- 
iflry.  But  tlie  ftrong  defire  of  reducing  every  thing  to  firii 
principles,  and  of  eftablilhing  a  theory  upon  incomplete  experi^ 
ments  or  fa6ls  imperfectly  feen,  did  not  admit  of  the  fmalleft 
©bftacles.  From  the  moment  that  analyfis  had  fliewn  fome  of 
the  principles  of  bodies,  the  chemift  thought  himfelf  in  poiTef- 
fion  of  the  firfl:  agents  of  nature.  He  confidered  himfelf  as 
authorized  to  regard  tliofe  bodies  as  elements  which  appeared  no 
longer  fufce|)tible  of  being  decompofcd.  Tlie  acids  and  the  al- 
kalis performed  the  principal  part  in  natural  operations  :  and  it 
:appeared  to  be  a  truth  buried  in  oblivion,  that  the  term  where 
the  artilt  (lops  is  not  the  point  at  which  the  Creator  has  limited 
his  power  :  and  that  the  lad  refult  of  analyfis  does  indeed  mark 
the  limits  of  art  but  does  not  fix  thofe  of  nature.  "We  miglij: 
iikewife  reproach  certain  chemiits  for  having  too  long  neglecl- 
€d  the  operations  of  the  living  fyftems.  They  confined  them- 
felves  in  their  laboratories,  iludied  no  bodies  but  in  their  life- 
lefs  ftate,  and  were  incapable  of  acquiring  any  knowledge  but 
fuch  as  was  very  incomplete  .-  for  he  who  in  his  refearches,  has 
no  other  oVy:(X  in  view  than  that  of  afcertaiiiing  the  principles 


PRELIMINARY   DISCOURSE.  2^ 

of  a  sttbftance,  afts  like  a  phyficlan  who  (houW  fuppofe  he  had 
acquired  a  complete  notion  of  the  human  body  by  confining 
his  fludies  to  the  dead  carcafs.  But  we  muft  likewife  obferve, 
that  in  order  to  form  a  proper  notion  of  the  phenomena  of  liv- 
ing bodies,  it  is  neceiTary  to  poflefs  the  means  of  confining  the 
gafeous  principles  which  efcape  from  bodies  ;  and  ofanalyfing 
thefe  volatile  and  inviiible  fubftances  which  combine  together. 
Now  this  work,  was  impolEble  at  that  time  ;  and  we  pught  to 
beware  of  imputing  to  men  thofe  errours  which  avife  from  the 
ftate  of  the  times  in  which  they  lived. 

It  may  pcrhups  be  demanded  on  this  occafion,  why 
chemiftry  wa3  fooner  known,  end  more  generally  culti- 
vated, in  Germany  and  in  the  North  than  in  our  kingdom.  I 
think  that  many  reafens  may  be  given  for  this.  In  the 
iirft  place  the  fcholars  of  Stahl  and  of  Becher  muft  have 
been  more  n-umerous,  and  confequently  their  inftruftion  far- 
ther extended.  Secondly  the  working  of  mines,  having  become 
a  refource  necefiary  to  the  governments  of  the  north,  has  been 
fingularly  encouraged  ;  and  that  chemiftry,  which  enlightens 
mineralogy,  muft  neceiTarily  have  participated  in  its  encourage- 
^ments.* 

Theftudyof  cht:miftry  did  not  begin  to  be  cultivated  toad- 
vantage  in  France  until  the  end  of  the  laft  century.  The  firft 
wars  of  Louis  XIV.  fo  projier  to  develope  the  talents  of  the  art- 
ift,  the  hiftorian  and  the  military  man,  appeared  little  favoura- 
ble to  the  peaceable  ftudy  of  nature.  The  naturalift  who  in  hh. 
refearches,  fees  union  and  harmony  around  him,  cannot  be  an 
indifferent  fpeftator  of  the  continual  fcenes  of  diforderand  de- 
ftrucStion  ;  and  his  genius  is  crufiied  in  the  midtl  of  troubles 
•and  agitations.  The  mind  of  the  great  Colbert,  deeply  pene- 
trated with  thefe  truths,  quickly  endeavoured  to  temper  the  fire 
of  difcord,  by  turning  the  minila.of  men  towards  the  only  objecla 

*  Since  the  French  government  has  facilitated  the  fludy  of  mmeralogy  by 
the  nigft  fupcrf)  eftabllflinicnts,  we  ^ave  beheld  the  tafte  for  chemiftry  revive; 
the  arts  which  have  the  workiug  of  jnetals  for  thtir  objeAhave  been  rendered 
snore  perfe<5l,  aiul  the  mines  whieli  have  been  wrought  are  more  numerous, 
•Mr.  bagc  has  been  more  particulrjiy  alfiduous  and  zealous  to  turn  the  fa- 
vour of  government  towards  this  objeiX  I  have  been  a  witnefs  to  the  labo- 
rious attention  of  this  chemlft  to  fffect  this  revolution.  I  have  beheld  the 
perfonal  facriilccs  he  made  to  brin^j  it  forward.  I  have  applauded  his  zeal, 
his  motives  :^nd  his  talents.  The  fanie  fentiments  ftill  occupy  my  mind; 
and  though  I  teach  a  dodlrine  at  pnfent  which  is  different  from  his,  this  cir- 
cumlbmce  arifcs  from  the  impoffibijity  of  commanding  opinions.  The  phi- 
h)fopher  who  is  truly  worthy  of  tliis  name,  is  capable  of  diftinguiUiing  ihe 
friend  of  his  heart  from  the  Hnve  of  his  fyflcm  ;  and  in  a  word,  every  cue 
i)ught  to  write  accorciing  to  his  convicSlion  ;  the  moft  facrcd  axiom  of  th.« 
ftiences  being  /*  Amicus  PlaiQjfed  in^.gia  arnica  Veritas." 


24  PRELIMINARY  DISCOURSfi. 

which  could  fecure  the  peace  and  profperlty  of  the  flate.  He 
exerted  himfelf  to  render  trade  flourifhing  ;  he  eflabliflied 
xnanufaftories  ;  learned  men  were  invited  from  all  parts,  en- 
couraged and  united  together,  to  promote  his  vaft  projedls. 
Then  it  was  that  the  ardour  of  enquiry  replaced  for  a  time  the 
fury  of  conquefl:  •,  and  France  very  foon  ftood  in  competition 
with  all  nations  for  the  rapid  progrefs  of  the  fcien^^,  and  the 
perfe£l^on  of  the  arts.  Lemery,  Homberg^  and  GeoiFroy  arofe 
nearly  at  the  fame  time  :  and  other  nations  vi^ere  no  longer  en- 
titled to  reproach  us  for  the  vi^ant  of  chemifts.  From  that  mo- 
ment the  exiftence  of  the  arts  appeared  to  be  well  ailured.  All 
the  fciences  which  afford  their  firft  principles,  were  cultivated 
■with  the  greateft  fuccefs  :  and  it  will  fcarcely  be  credited  that, 
in  the  fpace  of  a  few  years,  the  arts  were  drawn  from  a  ftate  of 
non-entity  ;  and  carried  to  fuch  a  degree  of  perfection,  that 
France,  which  had  before  received  every  thing  from  foreign 
countries,  became  in  pofleffion  of  the  glory  of  fupplying  its 
neighbours  with  models  and  with  merchandizes. 

Chemiftry  and  natural  hiftory,  hovv^ever,  at  the  beginning  of 
this  century,  were  cultivated  only  by  a  very  fmall  number  of 
perfons  ;  and  it  was  then  thought  that  the  fludy  of  thefe  fcien- 
ces ought  to  be  confined  to  the  academies.  But  two  men, 
whofe  names  will  be  ever  famous,  have  rendered  the  tafte  gen- 
eral under  the  reign  of  Louis  XV.  The  one  poflefTed  that  no- 
ble fpirit  which  is  a  ftranger  to  the  power  of  prejudice,  that 
indefatigable  ardour  which  fo  eafily  overcomes  every  obfbacle, 
that  opennefs  of  character  which  infpires  confidence,  and  trans- 
fufed  into  the  minds  of  his  pupils  that  enthufiafm  of  which  he 
himfelf  felt  the  force.  While  Rouelle  enlightened  the  fcience 
of  chemiftry,  Buffon  prepared  a  revolution  flill  more  aftonifhing 
in  natural  hiftory.  The  naturalifts  of  the  North  had  fucceed- 
cd  in  caufing  their  productions  to  be  read  by  a  fmall  number 
of  the  learned  ;  but  the  works  of  the  French  naturalift  were 
£oon,  like  thofe  of  nature,  in  the  hands  of  the  whole  world. 
He  pofFeired  the  art  of  diffunng  through  his  writings  tha;  Hvely 
intereft,  that  enchanting  colouring,  and  that  delicate  and  vigo- 
rous touch,  which  influence,  attach,  and  fubdue  the  mind. 
The  profundity  of  his  reafoning  is  every  where  united  to  all  that 
agreeable  illufion  which  the  molt  brilliant  imagination  can  fur- 
nifh.  The  facred  fire  of  genius  animates  all  his  producStions  ; 
his  fyftems  conftantly  exhibit  the  moft  fubllme  prcf^iects  in  their 
totality,  and  the  mod  perfect  corrcfpondence  in  their  minute 
parts:  and,  even  when  he  exhibits  mere  hypothefes,  we  are  in- 
clined  to  perfuade  ourfelves  that  they  are  eftabliflied  truths. 
We  become  Iik«  the  artift  who^  after  having  admired  a  beauti- 


■ 


PRELIMINARY   DISCOURSE.  25 

jful  ftatuc,  ufed  his  efforts  to  perfuade  himrelf  that  it  refplred, 
nnd  removed  every  thing  which  could  diffipate  his  ilJufion.  We 
take  up  his  work  with  a  pleafure  refembUng  that  of  the  man 
iwho  turns  again  to  fleep,  in  hopes  of  prolonging  the  deception 

f  an  agreeable  dream. 
Thefe  two  celebrated  men,  by  difFufmg  the  tafle  for  chemif- 

y  and  natural  hiftorv,  by  making  their  relations  and  ufes  bet- 
ter known,  conciliated  the  favour  of  government  towards  them  ; 
and  from  that  moment  every  one  interefted  himfelf  in  the  prog- 
refs  of  both  fciences.  Thofe  perfons  who  were  beft  quali- 
fied in  the  kingdom,  haftened  to  promote  the  revolution 
which  was  preparing.  The  fciences  foon  infcribed  in  their 
lilt  of  cultivators  the  beloved  and  refpecled  names  of  La  Roche- 
foucalt,  Ayen,  Chaulnes,  Lauraguais,  Malefherve,  &c.  ;  and 
thefe  men,  diftinguifhed  by  their  birth,  were  honoured  with  a. 
new  fpecies  of  glory,  which  is  independent  of  chance  or  pre- 
judice. They  enriched  chemillry  with  their  difcoveries,  and  af- 
fociated  their  names  with  all  the  other  literati  who  purfued  the 
fame  career.  They  revived  in  the  mind  of  the  chemift  that  paf- 
fion  for  glory,  and  that  ardour  for  the  publick  good,  which  con- 
tinually excite  new  efforts.  The  man  of  ambition  and  intrigue 
no  longer  endeavoured  to  deprefs  the  modefl  and  timid  man  o£ 
genius.  The  credit  of  men  in  place  ferved  as  a  defence  and 
fupport  againft  calumny  and  perfecution.  Rccompenfes  were 
afligned  to  merit.  Learned  men  were  defpatched  into  all  parts 
of  the  world,  to  fludy  the  arts,  and  colle£l  their  productions- 
Men  of  the  firft  merit  were  invited  to  inftrudt  us  with  regard 
to  our  own  proper  riches  •,  and  eftablifhments  of  chemiftry* 
which  were  made  in  the  principal  towns  of  the  kingdom,  dif- 
fufed  the  tafte  for  this  fcience,  and  fixed  among  us  thofe  arts 
which  we  might  in  vain  have  attempted  to  naturalize,  if  a  firm 
bafis  hid  not  been  firft  laid.  The  profeflbrs  eftablilhed  in  the 
capit;il  and  in  the  provinces,  appeared  to  be  placed  between  the 
academies  and  the  people,  to  prepare  the  latter  for  thofe  truths 
which  flow  from  fuch  refpe<fl:able  aflx)ciations.  We  may  con- 
fider  them  as  a  medium  which  refradts  and  modifies  the  rays 
of  light  that  iffue  from  thofe  various  luminous  centres  ;  and 
dlre6ls  them  towards  the  manufa£lorIes,  to  enlighten  and  im- 
prove their  pra(^tice.  Without  thefe  favours,  without  this  con- 
fideratlon  and  thefe  recompenfes,  could  it  have  been  expected 
that  the  moft  unafTuming  among  philofophers  would  have  exert- 
ed himfelf  to  promote  the  reputation  of  a  people  to  whom  he 
was  unknown  ?  Could  a  man  fo  fituated  reafonably  hope  to 
fuccced  in  carrying  a  difcovcry  into  effedt  ?  Is  It  probable  that 
he  Ihould  have  poflelTed  a  fufficient  fortune  to  work  In  the  large 
D 


26  PRELIMINARY   DISCOURSE. 

way,  and  by  this  means  alone  to  overcome  the  numberiefs  pre- 
judices which  baniih  men  of  Icience  from  manufadlorics  ?  The 
contemplative  fcicnces  demand  of  the  fovereign  repofe  and  lib- 
erty only  :  but  experimental  fciences  demand  more,  for  they 
require  affiftance  and  encouragement.  "What  indeed  could  be 
hoped  in  thofe  barbarous  ages  wherein  the  chemift  fcarce- 
ly  durft  avow  the  nature  of  the  occupation  which  in  fecret 
conftituted  his  greateft  plcafure.  The  title  of  chemift  was 
almoft  a  reproach  ;  and  the  prejudice  which  confounded  the 
profelfors  of  this  fcience  with  fuch  wretched  projeflors  as  are 
entitled  only  to  pity,  has  probably  kept  back  the  revival  of  the 
arts  for  feveral  centuries  •,  for  chemiftry  alone  can  afford  thenra 
proper  bafis.  If  the  princes  of  paft  times  had  been  friends  of 
the  arts  and  jealous  to  acquire  a  pure  and  durable  reputation  ;• 
if  they  had  been  careful  to  honour  the  learned,  to  collecl  their 
valuable  labours,  and  to  tranfmit  to  us  without  alteration  the 
precious  annals  of  human  genius  ;  we  fhould  have  been  difpen- 
fed  from  labouring  among  the  rubbifh  of  early  times,  to  con- 
fult  a  few  of  thofe  remains  which  have  efcaped  the  general 
wreck  ;  and  we  fliould  have  been  fpared  the  regret  of  allowing, 
after  many  ufclefs  refearchcs,  that  the  m after-pieces  of  anti- 
quity which  remain  anfwer  fcarcely  any  other  purpofe  than  to 
give  us  an  idea  of  that  fuperiority  to  which  the  earlier  nations 
had  arrived.  Time,  the  fword,  fire,  and  prejudice  have  devour- 
ed all :  and  our  refearehes  ferve  only  to  add  to  our  regret  for 
the  lofles  which  the  world  has  fuftaincd. 

The  fcience  of  chemiftry  poflefTes  the  glory,  in  our  days,  not 
only  of  having  obtained  the  prote6i:ion  of  government,  but  it 
may  likewife  boaft  of  another  equally  elevated.  This  fcience 
has  fixed  the  attention,  and  formed  the  occupation,  of  various 
men,  in  whom  the  habit  of  a  profound  ftudy  of  the  accurate 
fciences  had  produced  a  necelhty  of  admitting  nothing  but  what 
is  proved,  and  of  attaching  themfelves  only  to  fuch  branches  of 
knowledge  as  are  fufceptible  of  ftritl:  proofs.  Mclfrs.  De  la 
Grange,  Condorcet,  Vander,  Monde,  Monge,  Dc  la  Place, 
Meufnier,  Coufin,  the  moft  celebrated  mathematicians  of  Eu- 
rope, are  all  interefted  in  the  progrefs  of  this  fcience,  and  moft 
of  them  daily  add  to  its  progrefs  by  their  difcoveries. 
■  So  great  a  mafs  of  inftru(ilion,  and  fuch  ample  encourage- 
ment, could  not  but  efFefl  a  revolution  in  the  fcience  itfelf  j,  and 
we  are  indebted  to  the  combined  efforts  of  all  thefe  learned 
men  for  the  difcovery  of  feveral  metals,  the  creation  of  various 
ufeful  arts,  the  knowledge  of  a  number  of  advantageous  procef* 
ies,  the  working  of  feveral  mines,  the  analyfis  of  the  gafes,  the 
dccompofition  of  water,  the  theory  of  heat,  the  dodrinc  of  com- 
buftion  5  and  a  mafs  of  knowledge  fo  abfolute  and.  fo  extended. 


PRELIMINARY    DISCOURSE.  27 

icfpecting  all  the  phenomena  of  art  and  of  nature,  that  in  a  very 
fliort  time  chemiflry  has  become  a  fcience  entirely  new.  We 
might  now  fay  with  much  more  truth  what  the  celebrated  Bacon 
affirmed  of  the  chemiftry  of  his  time  ;  "A  new  philofophy," 
Tays  he,  «<  has  iflued  from  the  furnaces  of  the  chemifts,  which 
has  confounded  all  the  reafonings  of  the  ancients." 

But  while  difcoveries  became  infinitely  multiplied  in  chem- 
iftry,  the  neceihty   of  remedying  the    confufion  which  had  fo 
Jong  prevailed,  was  foon  feen,  and  indicated   the  want  of  a  re- 
.form  in  the  language  of  this  fcience.     There  is  fo  intimate  a  re- 
lation between  words  and  fafts,  that  the  revolution  which  takes 
place  in  the  principles  of  a  fcience  ought  to  be  attended  with  a 
fimilar  revolution  in  its  language  :  and  it  is  no  more  poffible  to 
prefcrve  a  vicious  nomenclature  with   a  fcience  which  becomes 
enlightened,   extended,  and   fimplified,  than  to  polifh,  civilize, 
and  inftiucl  uninformed  man  without  making  any  change  in  his 
.natural  language.     Every   chemiit  who  wrote   on  any  fubjedt 
was  ftruck  with  the  inaccuracy  of  the  words   in   common  ufe, 
and  confidered  himfelf  as  authorized  to  introduce  fome  change  ; 
infomuch  that  the  chemical  language  became  infenfibly  longer, 
more  confufed,  and  more  unpleafant.     Thus  carbonick  acid  has 
been  known  during  the  courfe  of  a  few  years,  under  tiie  names 
of  Fixed  Air,  Aerial  Acid,  Mephitick  Acid,  Cretaceous  Acid, 
occ.  ;  and  our  pofterity  may  hereafter  difpute  whether  thefe  va- 
rious denominations  were    not  applied  to   different  fubftances. 
The  time  was  therefore  come,  in  which  it  was  neceflary  to  re- 
form the  language  of  chemiftry  ;  the  imperfedions  of  the  an- 
.cicnt  nomenclature,  and  the  difccvery  of  many  new  fubftances, 
rendered  this   revolution   indifpenfable.     ^ut  it  was  necefiary 
to  defend  this  revolution  from  the  caprice  and  fancy  of  a  few 
individuals  ;  it  was  neceftary  to  eftablifti  'this  new  language  up- 
on invariable  principles  :  and  the   only   means   of  infuring  this 
purpofe  was  doubtlefs  that  of  erecting  a  tribunal  in  v^hich  chem- 
ifts of  acknowledged    merit  fhould  difcufs  the  words  received, 
.without  prejudice  and  without  interelt  ;  in  which   the   princi- 
ples of  a  new  nomenclature  might  be  eftabliOied  and  purified  by 
the   fevereft  logick  ;  and  in  which  the  language  {hould  be  fo 
well  identified    with   the  fcience,   the  word  fo  v.'ell  applied  to 
the  fa£l:,  that   the  knowledge    of  the  one   ftiould   lead   to  the 
knowledge  of  the  other.     This  was  executed  in  1 788  by  Meflrs. 
De  Morveau,  Lavoifier,  Berthollet,  and  De  Fourcroy. 

In  order  to  eftablifti  a  fyftem  of  nomenclature,  bodies  muft: 
;be  confidered  in  two  difix^rent  points  o,f  viev/,  and  diftributed 
into  two  claiTes  ;  namely,  the  clafs  of  fimple  fubftances  reputed 
to  be  elementary^  and  the  clafs  of  combined  fubftances. 


28  PRELIMINARY  DISCOURSE. 

I.  The   mod  natural  and  fultable  denominations   uhich  can 
be  afligned  to  fimple  fubftanccs,  muft  be  deduced  from  a  princir 
pie  and  charadleril'lick  property  of  the  fubftance  intended  to  be 
exprefTed.     They  may  likewife  be  diftinguiflied  by  words  which 
^o  not  prefent  any  precife  idea  to  the  mind.     Mofl  of  the  re- 
ceived  names  arc  eftablilhed  on   this  laft  principle,  fuch  as  the 
names  of  Sulphur,  Fhofphorus,  which  do  not  convey  any  figni- 
iication  in  our  language,  and  produce  in  our  minds  determinate 
ideas  only,  becaufe  ufage  has  applied  them  to  known  fubftances. 
Thefe  words,  rendered  facred  by  ufe,  ought  to  be  preferved  in 
a  nev/  nomenclature  ;  and  no  change  ought  to  be  made,  except- 
ing when  it  is  propofed  to  redlify  vicious  denominations.     In 
this  cafe  the  Jiuthors  of  the  New  Nomenclature  have  thought  it 
proper  to  deduce  the   denomination  from  the   principal  char- 
iicleriftick  property    of  the  fubitance.     Thus,    pure  air  might 
have  been   called  Vital  Air,  Fire  Air,  or  Oxigenous  Gas  *,  be- 
caufe it  is  the  bafis  of  acids,  and  the  aliment  of  refpiration  and 
combullion.     But  it  appears  to  me  that  this  principle  has  been 
in  a  fmall  degree  departed  from  when  the  name  of  Azotick  Gas 
was  given  to  the  atmofpherical  mephitis— i.  Becaufe  none  of 
the  known  gafeous  fubllances  excepting  vital  air  being  proper 
for  refpiration,  the  word  Azote  agrees  with  every  one  of  them 
except  one  ;  ^nd  confeqiiently  this  denomination  is  not  found- 
ed upon  an    exclufive  property,  di{tin(ftive  and  characfteriftick 
of  the  gas    itfelf.  2.  This  denomination  being  once  introduced, 
the  nitrick  acid  ought  to  have   been  called  Azotick  Acid,  and 
its  cominnations   Azotates  \  becaufe  the  acids  are  propofed  to 
be  denoted  by  the  name  which  belongs   to  their  radical.     3.  ^ 
the  denomination  of  Azotick  Gas  does  not  agree  with  this  aeri- 
form fubii:ance,the  name  of  Azote  agrees  ftililefs  with  the  coii- 
crete  and  fixed  fubftance  ;  for  in  this  ftate  all  the  gafes  are  ef- 
fentially  azotes.     It  appears  to  me  therefore  that  the  denomina- 
tion of  Azotick  Gas  is  not  eilabiiflied  according  to  the  principles 
whicli  have  been  adopted  ;  and  that  the  names  given  to  the  fev- 
eral  fubllances  of  which  this  gas  conftitutes  one  of  the  elements, 
are  equally  rem.oyed   from  the  principles  of  the  Nomenclature. 
In  order  to  correcTt   the   Nomenclature  on  this  head,  nothing 
more  is  neceiTary  than  to  fubftitute  to  this  word  a  denomination 
which  is  derived  from  the  general  fyft em  made  ufe  of :  and  I 
have  prefumed  to  propofe  that  of  Nitrogene  Gas.     In   the  firft 
place,  it  is  deduced  from  the  exclufive  and  chara6lerillick  prop- 
erty of  this  gas,  whicii  forms  the  radical  of  the  nitrick  acid.    By 
this  means  we  (hail  preferve  to  the  combinations  of  this  fubftance 
the  received  denominations,  fuch  as  thofe  of  the  Nitrick  Acid, 
Nitrates,  Nitrites,  &c.     In  this  manner  the  word,  which  is  r.J 


m 


PRELIMINARY   DISCOURSE.  c^ 

forded  by  the  principles,  adopted  by  the  celebrated  authors  of 
ihe  nomenclature,  caufes  every  thing  to  return  into  the    order 
ropofcd  to  be  eltablifhed. 

2.  The  method  made   ufe  of  to  afcertain  the  denominations 
uitable  to  compound   fubftances   appears  to  me    to  be  fimplc 
and  accurate.     It  has  been  thought  that  the  language  of  this 
part  of  fcience  ought  to  prefent  the  analyfes  ;    that  the  words 
ihould  be  only  the  expreflion  of  fadls  ;    and  that  confequently 
the  denomination  applied  by  a  chemift  to  any  fubftance  which 
has  been  analyfed,  ouc^ht  to  render  him  acquainted  with  its  con- 
llituent  parts.     By  following  this  method,  the  Nomenclature  is 
as  it  were  united,  and  identified  with  the  fcience  j  and  fa6i:s  and 
words  agree  together.     Two  things  are  therefore  united,  which 
until  this  time  appeared  to  have  no  mutual  relation,  the  word, 
and  the  fubftance  which  it  reprefented  ;  and  by  this  means  the 
{ludy  of  chemiftry  is  firnplified.  But  when  we  apply  thefe  incon- 
teftible  principles  to  the  various  otje£ls  of  chemiitry  we  ought 
to  follow  the  analyfis  ftep  by  ftep,  and  upon  this  ground  alone 
eilabiifh  general  and  individual  denominations.      We  ought  to 
obferve,  that  it  is  from  this   analytical  method  that  the  various 
denominations  have  been  afligned,   and  that  the  methodical  dif- 
tributions  of  natural  h},ftory  have  been  at  all  times  made.   If  man 
were  to  open  his  eyes  for  the  firft  time  upon  the  various  beings 
which  people  or  compofe  this  globe,  he  would  eftabiiih  their 
relation  upon  the  comparifon  of  their  mofi:  evident  properties, 
and  no  doubt  would  found  his  firfl  divifions  upon  the  mod  fen- 
fible  differences.     The  various  modes  of  exiftence,  or  their  fev- 
eral  degrees  of  confidence,  would  form  his  fir  ft  divifion  ;  and 
he  would  arrange  them  under  the  heads  of  folid,  liquid,   or 
aeriform  bodies.     A  more  profound  examination,    and  a  more 
conneOed   analyfis  of  the  individuals,   would  foon  convince 
hiniithat  the  fubftances  which  certain  general  relations  had  in- 
duced him  to  unite  in  the  fame  claTs,  under  a  generick  denomi- 
nation, differed  very  elfentially  among  each  other,   and  that 
thefe  dirTerences  neceffarily  required  fubdivifion.      Hence  he 
would  divide  his  folid  bodies  into  ftones,  metals,  vegetable  fub- 
ftances, animal  fubftances,  &c.    his  liquids  would   be   divided 
into  water,  vital  air,  inflammable  air,  mephitick  air,  &c.     When 
he  proceeded  to  carry  his  refearches  on  the  nature  of  thefe  fub- 
ftances ftill  farther,  he  would  perceive  that  moft  of  the  individ- 
uals were  formed  by  the  union  of  fimple  principles  ;  and  here 
it  is  that  his  applications  of  the  fyftem  to  be  followed,  in  afhgn- 
ing  a  fuitable  denomination  to   each  fubftance,  would  begin. 
To  anfwer  this  purpofe,  the  authors  of  tlie  New  Nomenclature 
have  endeavoured  to  e:;hibit  denominations  which  may  point 


30  PRELIMINARY  DISCOURSE. 

.out  the  conftituent  principles.  This  admirable  plan  has  been 
carried  into  execution  as  far  as  relates  to  fubftances  which  are 
not  very  complicated,  fuch  as  the  combinations  of  the  principles 
with  each  other ;  the  acids,  earths,  metals,  alkalis,  &c.  And 
this  part  of  the  Nomenclature  appears  to  me  to  leave  nothhig 
more  to  be  defired.  The  explanation  may  be  feen  in  the  work 
publiOied  on  this  fubject  by  the  authors,  and  in  the  Elementary 
Treatife  of  Chemiftry  of  Mr.  Lavoifier.  I  {hail  therefore  do 
jioihing  more  in  this  place  than  prefent  a  iketch  of  the  method 
I  have  followed  ;  taking  for  example  the  combinations  of  acids, 
which  form  the  molt  numerous  clafs  of  compounds. 

The  full  Hep  confifted  in  comprehending  under  a  general  de- 
nominatioii  the  combination  of  an  acid  with  any  given  bads, 
and  in  order  to  obierve  a  more  exacSl  arrangement,  and  at  the 
fame  time  to  afiift  the  memory,  one  common  termination  has 
been  given  to  all  words  which  denote  the  combination  of  an 
acid.  Hence  the  words  Sulphates,  Nitrates,  Muriates,  are  ufed 
to  denote  combinations  of  the  fulphurick,  nitrick,  and  muriatick 
acids.  The  kind  of  combination  is  denoted  by  adding  to  the 
generick  word  the  name  of  the  body  wjiich  is  combined  with  the 
acid ;  thus,  the  fulphate  of  pot-afh  exp^efTes  the  combination  of 
the  fulphurick  acid  with  pot-afh. 

The  modifications  of  thefe  fame  acids,  dependent  on  the 
proportions  of  their  conftituent  principles,  form  falts  dilFercnt 
from  thofe  we  have  juil  fpoken  of;  and  the  authors  of  the  New 
Nomenclature  have  expreflcd  the  modifications  of  the  acids  by 
the  termination  of  the  generick  word.  The  difference  in  the 
acids  arifes  almoll  always  from  the  greater  or  leis  abundance  of 
oxigene.  In  the  firll  cafe,  the  acid  affumes  the  epithet  of  Oxi- 
genated  ;  hence  the  oxigenated  muriatick  acid,  the  oxigenated 
fulphurick  acid,  &c.  In  the  fecond  cafe,  the  termination  of  the 
word  which  denotes  the  ^id,  ends  in  ous  ;  hence  the  fuiphur- 
ous  acid,  the  nitrous  acid,  Sec.  The  combinations  of  thefd  Jaft 
form  fulphites,  nitrites,  &c.  *,  the  combinations  of  the  former 
compofe  oxigenated  muriates,  oxigenated  fulphates,  &c. 

The  combinations  of  the  various  bodies  which  compofe  this 
globe  are  not  all  as  fimple  as  thofe  here  mentioned  ,  and  it  may- 
be immediately  perceived  how  long  and  troublefome  the  denom- 
inations Would  be,  if  attempts  were  made  to  bellow  a  fuigle 
denominatioji  which  fhould  denote  the  conftituent  principles  of 
a  body  form.ed  by  the  union  of  five  or  fix  principles.  In  this 
cafe,  the  preference  has  been  given  to  the  received  appellation, 
and  no  other  changes  have  been  admitted  but  fucli  as  were  ne- 
ceflary  in  order  to  fubilitute  proper  appellations,  inllead  of  thofe 
which  afi^crded  notions  contrary  to  the  nature  of  the  objects  they 
were  applied  to. 


PRELIMINARY  DISCOURSE.  3? 

1  have  adopted  tins  Nomenclature  in  my  lectures,  and  inmy 
iitings  *,  I  have  not  failed  to  perceive  how  very  advantageous 
It  is  to  the  teacher,  how  much  it  reheves  the  memory,  how 
greatly  it  tends  to  produce  a  tafte  for  chemKtry,  and  with  what 
facility  and  precifion  the  ideas  and  principles  concerning  the  na- 
ture of  bodies  fix  themfclves  in  the  minds  of  the  audttars.  But 
i  have  been  careful  to  infert  the  technical  terms  ufed  in  the  arts, 
or  received  in  fociety,  together  with  thefe  new  denominations. 
I  am  of  opinion  that,  as  it  is  impoflible  to  change  the  language 
of  the  people,  it  is  neceflary  to  defcend  to  them,  and  by  that 
means  render  them  partakers  of  our  difcoveries.  We  fee,  for 
example,  that  the  artift  is  acquainted  with  the  fulphurick  acid 
by  no  other  name  than  that  of  Oil  of  Vitriol,  though  the  name 
of  the  Vitriolick  Acid  has  been  the  language  of  chemifts  for  a 
century  pad.  We  cannot  hope  to  be  more  happy  in  this  refpe(ffc 
than  our  predecefibrs  ;  and,  fo  far  from  feparating  ourfelves' 
from  the  artift  by  a  peculiar  language,  it  is  proper  that  we  fhould. 
multiply  the  occafions  of  bringing  us  together;  fo  far  from  at- 
tempting to  enflave  him  by  our  language,  we  ought  rather  to 
infpire  his  confidence  by  learning  his  terms.  Let  us  prove  to  the 
artift  that  our  relations  with  him  are  more  extended  than  he 
imagines  ;  and  let  us  by  this  intimacy  eftablifh  mutual  corref- 
pondence,  and  a  concurrence  of  information,  which  cannot  but 
redound  to  the  advantage  of  the  arts  and  of  chemiftry. 

After  having  explained  the  principal  obje<3:ions  which  have 
retarded  the  improvement  of  chemiftry,  and  the  caufes  which 
in  our  time  have  accelerated  its  progrefs,  we  (hall  endeavour  to 
point  out  the  principal  applications  of  this  fcience  ;  in  which 
attempt,  we  think,  we  (hall  fucceed  beft  by  cafting  a  general 
retrofpeft  over  thofe  arts  and  fciences  v/hich  receive  certain 
principles  from  it. 

Moft  of  the  arts  are  indebted  to  accident  for  their  difcovcry. 
They  are  in  general  neither  the  fruit  of  refearch,  nor  the  refult 
of  combination,  but  all  of  them  have  a  more  or  lefs  eyident 
relation  to  chemiftry.  This  fcience  therefore  is  capable  of  clear- 
ing up  their  firft  principles,  reforming  their  abufes,  fimplifyiijg 
their  operations,  and  accelerating  their  progrefs. 

Chemiftry  bears  the  fame  relation  to  moft  of  the  arfs,  as  the 
mathematick  have  to  the  feveral  parts  of  fcience  which  depend 
ou  their  principles.  It  is  polRblc,  no  doubt,  that  works  of  me- 
chanifm  may  be  executed  by  one  who  is  no  mathematician  ; 
and  fo  likewife  it  is  poflible  to  die  a  beautiful  fcarlet  without 
being  a  chemift  :  but  the  operations  of  the  mechanick,  and  of 
the  dyer,  are  not  the  lefs  founded  upon  invariable  principles,  the 
knowledge  of  which  would  be  of  infinite  utility  to  the  artift. 


3!i  PRELIMINARY  .DISCOURSE. 

We  continually  hear  in  manuFadlories  of  the  caprices  and  un- 
certainty of  operations  ;  but  it  appears  to  me  that  this  vague 
expreflion  owes  its  birth  to  the  ignorance  of  the  workmen  wit!\ 
regard  to  the  true  principles  of  their  art.  For  nature  itfelf  does 
not  a6t  with  determination  and  difcernment,  but  obeys  invaria- 
ble laws ;  and  the  inanimate  fubftance  which  we  make  ufe  of 
in  our  manufadtures,  exhibits  neceflary  effefls,  in  which  the 
will  has  no  part,  and  confequently  in  which  caprices  cannot 
take  place.  Render  yourfelves  better  acquainted  with  the  ma- 
terials you  work  upon,  we  might  fay  to  the  artills  ;  ftudy  more 
intimately  the  principles  of  your  art  ;  and  you  vi'ill  be  able  to 
forefce,  to  predi£l,  and  to  calculate  every  effedl.  It  is  your  ig- 
norance alone  which  renders  your  operations  a  continual  feries 
of  trials,  and  a  difcouraging  alternative  of  fuccefs  and  difap- 
pointment. 

The  publick,  which  continually  exclaims  that  experience  is 
better  than  fcience,  encourages  and  fupports  this  ignorance  on 
the  part  of  the  artiffc ;  and  it  will  not  be  remote  from  our  ob- 
je6l  to  attempt  to  afcsrtain  the  true  value  of  thefe  terms.  It  is 
very  true,  for  example,  that  a  man  who  has  had  a  very  long 
experience  may  perform  operations  wirh  exadtnefs  ;  but  he  will 
always  be  confined  to  the  mere  manipulation.  I  would  com- 
pare fuch  a  man  to  a  blind  perfon  who  is  acqustinted  with  the 
road,  and  can  pafs  along  it  with  eafe,  and  perhaps  even  with  the 
confidence  and  afTurance  of  a  man  who  fees  perfectly  well  j  but 
is  at  the  fame  time  incapable  of  avoiding  accidental  obftacles, 
incapable  of  (hortenlng  his  way  or  taking  the  mod  dire<fl:  courfe, 
and  incapable  of  laying  down  any  rules  which  he  can  commu- 
nicate to  others.  This  is  the  (late  of  the  art i ft  of  mere  experi- 
ence 5  however  long  the  duration  of  his  pratlice  may  have  been, 
as  the  fimple  performer  of  operations. 

It  may  perhaps  be  replied,  that  artifts  have  made  very  Impor- 
tant difcoveries  in  confequenCe  of  afliduous  labour.  This  is  in- 
deed true,  but  the  examples  are  very  fcarce  ;  and  we  have  na 
right  to  conclude,  becaufe  we  have  feen  mcn'of  genius  without 
any  mathematical  theory  execute  wonderful  works  of  mechan- 
ifm,  that  the  mathematicks  are  not  the  bafis,  or  that  any  one  has 
a  right  to  expedl:  to  become  a  great  mechanick  without  a  pro^ 
found  ftudy  of  mathematical  principles. 

It  appears  to  be  generally  admitted  at  prefent,  that  chemiftry 
is  the  bafis  of  the  arts  :  but  the  artift  will  not  derive  from  chem- 
iftry all  the  advantages  he  has  a  right  to  expe<ft,  until  he  has 
broken  through  that  powerful  barrier  which  fufpicion,  felf-love, 
and  prejudice  have  raifed  between  the  cheniift  and  himfelf. 
Suchphilofophers  as  have  attempted  to  pafs  this  line,  have  fre- 


PRELIMINARY   DISCOURSE.  35 

quently  been  repelled  as  dangerous  innovators  -,  and  prejudice, 
which  reigns  defpotically  in  manufactories,  has  not  even  permit- 
ted it  to  be  thought  the  proceir;is  were  capable  of  improvementi 

II  is  eafy  to  fliew  the  advantages  which  the  arts  might  obtain 
from,  chemiilry,  by  cafting  a  retrofpe^t  over  its  applications  to 
each  of  them  in  particular. 

I.  It  appears,  from  the  writings  of  Columella,  that  the  an- 
cients poilefled  a  confiderable  extent  of  knowledge  refpe£ling 
agriculture,  which  was  at  that  time  confidered  as  the  firft  and 
nobleft  occupation  of  man.  But  when  once  the  obje£ls  of  lux- 
ury prevailed  over  thofe  of  necelTity,  the  cultivation  of  the 
ground  was  left  to  the  mere  fucceffion  of  practice,  and  this  firlt 
of  the  arts  became  degraded  by  prejudices. 

Agriculture  is  more  intimately  connefted  with  chemiftry  than 
is  ufually  fuppofed.  It  muft  be  admitted  that  every  man  is  ca- 
pable of  caufing  ground  to  bear  corn  ;  but  what  a  confiderable 
extent  of  knowledge  is  neceflary  to  caufe  it  to  produce  the 
greateft  pofiible  quantity  !  It  is  not  enough,  for  this  purpofe,  to 
divide,  to  cultivate  and  to  manure  any  piece  of  ground  :  a  mix- 
ture is  likewiie  required  of  earthy  principles  fo  well  aflbrted, 
that  it  may  afford  a  proper  nourifliment ;  permit  the  roots  to 
extend  themfelves  to  a  diftance,  in  order  to  draw  up  the  nutri- 
tive juices  ;  give  the  ftem  a  fixed  bafe  ;  receive,  retain,  and  af- 
ford upon  occafion,  the  aqueous  principle,  without  which  no 
vegetation  can  be  performed.  It  is  therefore  effential  to  afcer- 
tain  the  nature  of  the  earth,  the  avidity  with  which  it  feizes 
water,  its  force  of  retaining  it,  &c.  5  and  thefe  requifites  point 
to  fladies  which  will  afford  principles  not  to  be  obtained  by- 
mere  practice  but  ilowly  and  imperfectly. 

Every  grain  requires  a  peculiar  earth.  Barley  vegetates  free- 
ly among  the  dry  remains  of  granite  ;  wheat  grows  in  calcare- 
ous earth,  &c.  And  how  can  it  be  poffible  to  naturalize  for- 
eign produtfls,  without  a  fufiicient  ftock  of  knowledge  to  fupply 
them  with  an  earth  fimilar  to  that  which  is  natural  to  them  ? 

The  diforders  of  grain  and  forage,  and  the  defiarudtion  of  the 
infects  which  devour  them,  are  obje<Sts  of  natural  hiflory  and 
chemiitry  :  and  we  have  feen  in  our  ov/n  times  the  effential  art 
of  drying  and  preferving  grain,  and  all  thofe  details  which  are 
interefting  in  the  preparation  of  bread,  carried  by  the  labours  of 
a  few  chemilts  to  a  degree  of  perfection  which  feemed  difficult 
to  have  been  attained. 

The  art  of  difpofing  (tables  in  a  proper  manner,  that  of  choof- 
ing  water  adapted  for  ihz  drink  of  domeftick  animals,  the  econ- 
omical procefles  for  preparing  and  mixing  their  food,  the  un- 
common talent  of  fupplying  a  proper  manure  fuited  to  the  na^ 
E 


34  PRELIMINARY   DISCOURSE. 

ture  of  foilsj  the  knowledge  necefiury  to  prevent  or  to  repair  th:^ 
effects  of  blights — all  come  within  the  province  of  chemlftry  ; 
nnd  without  the  afliftance  of  this  fcience  cur  proceeding  would 
be  painful,  flow,  and  uncertain. 

We  may  at  prefent  infill  upon  the  neceffity  of  chemlftry  in 
the  various  branches  of  agriculture  with  fo  much  the  more  rea- 
fon,  as  government  does  not  ceafe  to  encourage  this  firlt  of  arts 
by  recompcnfes,  diftincSlionSj  and  eftablilhments  ;  and  the  view* 
of  the  (late  are  forwarded  by  the  propofal  of  means  to  render 
this  art  flour) ffiing.  We  fee,  with  the  greateft  fatisfajSlion,  that, 
by  a  happy  turn  of  reflection,  we  begin  to  confider  agriculture 
2s  the  pureffc,  the  mod  fruitful,  and  the  moft  natural  iource 
of  our  riches.  Prejudices  no  longer  tend  to  opprefs  the  huf- 
bandman.  Contempt  and  fervitude  are  no  longer  the  inherit- 
ance received  for  Ids  incelTant  labours.-  The  mod  ufeful  and 
the  moft  virtuous  clals  of  men  is  likewife  that  whofe  flute  is 
moft  minutely  confidered  ;  and  the  cultivator  of- the  ground  in 
France  is  at  laii:  permitted  to  raife  his  hands  in  a  (late  of  free- 
dom to  heaven,  in  gratitude  for  this  happy  revolution. 

2.  The  working  of  mines  is  likewife  founded  upon  the  prin- 
ciples of  chemiftry.  This  fcience  alone  points  out  and  directs 
the  feries  of  operations  to  be  made  upon  a  metal,  from  the  mo- 
ment of  its  extraction  from  the  earth  until  it  comes  to  be  ufed 
in  the  arts. 

Before  the  chemical  analyfis  was  applied  to  the  examination 
of  ftones,  thefe  fubftances  were  all  denoted  by  fuperlicial  char- 
a£lers,  fuch  as  colour,  hardnefs,  volume,  weight,  form,  and  the 
property  of  giving  fire  with  the  fteel.  All  thefe  circumftances 
had  given  rile  to  methods  of  divilion  in  which  every  other  prop- 
erty was  confounded  ;  but  the  fuccelTive  labours  of  Pott,  Mar- 
graafF,  Bergmann,  Scheele,  Bayen,  Dietrich,  Kirwan,  Lavoifier, 
De  Morveau,  Achard,  Sage,  Berthollet,  Jerhard,  Erhmann, 
Fourcroy,  Mongez,  Klaproth,  Creii,  Pelletier,  De  la  Metherie, 
SiC.  by  inftru6ling  us  concerning  the  conftituent  principles  of 
every  known  ftone,  have  placed  thefe  fubftances  in  their  prop- 
er fituations,  and  have  carried  this  part  of  chemiftry  to  the  fame 
degree  of  precifon  as  that  which  we  before  polfeflTed  refpe<5ling 
the  neutral  falts. 

The  natural  hiftory  of  the  mineral  kingdom,  unafTifted  by 
chemiftry,  is  a  language  compofed  of  a  few  words,  the  knowl. 
edge  of  which  has  acquired  the  name  of  Mineralogift  to  many 
perfons.  The  words  Calcareous  Stone,  Granite,  Spar,  Schorlc, 
Feld  Spar,  Schiftus,  Mica,  Sec.  alone  compofc  the  di£lionary  of 
feveral  amateurs,  of  natural  hiftory  ;  but  the  difpofition  of  thefe 
fubftances  in  the  bowels  of  the  earth,  their  refpedlive  poHtion 


PRELIMINARY    DISCOURSE.  3^ 

•In  the  compofition  of  the  globe,  their  formation  and  fuccefTive 

.decompofitions,  their  ufes  in  the  arts,  and  the  knowledge  of  their 
conftituent  principles,  form  a  fcience  which  can  be  well  known 

•  and  inveftigated  by  the  chemift  only. 

It  is  neceflary  therefore  that  mineralogy  (hould  be  enlighten- 
ed by  the  ftudy  of  themiftry  ;  and  we  may  oblcrve  that,  fincc 
thefe  two  fciences  have  been  united,  the  labour  of  working  mipes 
has  been  fnnplified,  metallick  ores  have  been  wrought  with 
more  intelligence,  feveral  new  metallick  fubftances  have  beeu 
difcovcred,  individuals  have  opened  mines    in  the  provinces  ; 

.and  we  have  become  familiar  with  a  fpecies  of  induftry  which 
feemed  foreign,  and  almoil  incompatible  with  our  foil  and  our 
habits.  Steel  and  the  other  metals  liave  received  in  our  manu- 
factories that  degree  of  perfc6lion  which  had  till  lately  excited 
our  admiration,  and  hurnilitated  our  felf-love.  The  fuperb 
manufadlure  of  Creulbt  has  no  equal  in  Europe.  Moft  of  our 
works  are  fupported  by  pit-coal ;  and  this  new  combullible  fub- 
llance  is  fo  much  the  more  valuable,  as  it  affords  us  time  to  re- 
pair our  exhaulled  woods,  and  as  it  is  found  almofl  every  where 
in  thofe  barren  foils  which  repel  the  ploughfhare,  and  prohibit 
every  other  kind  of  induftry.      The   eternal  gratitude  of  this 

.country  is  therefore  due  to  MefTrs.  Jars,  Dietrich,  Duhamel, 
Monet,  Genfanne,  .&c.  who  firft  brought  us  acquainted  with 
thefe  true  riches.  The  tafte  for  mineralogy,  which  has  diffufed 
itfelf  within  our  rem.embrance,  has  not  a  little  contributed  to 
produce  this  revolution  ;  and  it  is  in  a  great  meafure  owing  to 
thofe  colle(fl;ions  of  natural  hiftory,  againil  which  fomc  perfons 

ihave  fo  much  exclaimed,  that  we  are  indebted   for  this  general 

;talte.  Our  colle£\ions  have  the  fame  relation  to  natural  hiftory, 
as  books  bear  to  literature  and  the  fciences.  The  coileftion 
frequently  is  nothing  more  than  an  objeft  of  luxury  to  the  pro- 
prietor ;  but  in  this  very  cafe  it  is  a  refource  always  open  to 
the  man  who  is  defirous  of  beholding,  and  inftructing  himfelf. 
It  is  an  exemplar  of  the  works  of  nature,  which  maybe  confult- 
ed  every  moment  •,  and  the  chemift  who  runs  over  all  thefe 
prod u«5lions,  and  fubje^ls  them  to  analyfes  to  afcertain  their 
conilltuent  principles,  forms  the  precious  chain  which  unites 
nature  and  art. 

3.  While  the  chemift  attends  to  the  nature  of  bodies,  and  en- 
deavours to  afcertain  their  conitituent  principles,  the  natural 
philofopher  ftudies  their  external  characlcrs,  and  as  it  were 
their  pliyfiognomy.  The  objed  of  the  chcmilt  ought  therefore 
to  be  united  to  that  of  the  philofopher,  in  order  to  acquire  a 
romplete  idea  of  a  body.  What  in  fad  fliall  we  call  Air  or 
.■ire,  without  the  inurutlion  of  the  chtmift  ?  Fluids  more  or 


3^  PRELIMINARY   DISCOURSE. 

lefs  compreflible,  ponderous  and  elaftick.  What  are  the  parr 
ticulars  of  information  which  natural  philofophy  affords  us  con- 
cerning the  nature  of  folids  ?  It  teaches  us  to  diftinguifh  them 
from  each  other,  to  calculate  their  weight,  to  determine  their 
figure,  to  afcertain  their  ufes,  &c. 

If  we  caft  our  attention  upon  the  numerous  particulars  which 
chemiftry  has  lately  taught  us  refpecting  air,  water,  and  fire,  we 
Ihall  perceive  how  much  the  connexion  of  thefe  two  fciences 
has  been  ftrengthened.  Before  this  revolution,  natural  philofo- 
phy was  reduced  to  the  fimple  difplay  of  machines  ;  and  this 
coquetry,  by  giving  it  a  tranfient  glare,  would  have  impeded  its 
progrefs,  if  chemiftry  had  not  reflored  it  to  its  true  deftination. 
The  celebrated  chancellor  Bacon  compared  the  natural  magick, 
or  experimental  philofophy,  of  his  time,  to  a  magazine  in  which 
a  few  rich  and  valuable  moveables  were  found  among  a  heap  of 
toys.  The  curious,  fays  he,  is  exhibited  inftead  of  the  ufeful^ 
What  more  is  required  to  draw  the  attention  of  great  men,  and 
to  form  that  tranfient  fafliion  of  the  day  which  ends  in  con- 
tempt ? 

The  natural  philofophy  of  our  days  no  longer  deferves  the  re- 
proaches of  this  celebrated  philofopher.  It  is  a  fcience  found- 
ed on  two  bafes  equally  folid.  On  the  one  part,  it  depends  on 
mathematical  fcience  for  its  principles  ;  and,  on  the  other  it 
Tefls  upon  chemiftry.  The  natural  philofopher  will  attend 
equally  to  both  fciences. 

The  ftudy  of  chemiftry,  in  certain  departments,  is  fo  inti- 
STiately  connected  with  that  of  natural  philofophy,  that  they  are 
infeparable  ;  as,  for  example,  in  refearches  concerning  air,  wa- 
ter, fire,  &c.  Thefe  fciences  very  advantageoufly  affift  each 
other  in  other  refpe£l:s  ;  and  while  the  chemift  clears  minerals 
from  the  foreign  bodies  which  are  combined  with  them,  the 
philofopher  fupplies  the  mechanical  apparatus  necelTary  for  ex- 
ploring them.  Chemiftry  is  infeparable  from  natural  philofo- 
phy, even  in  fuch  parts  as  appear  the  moft  independent  of  it  , 
fuch,  for  example  as  opticks,  where  the  natural  philofopher  can 
make  no  progrefs  but  in  proportion  as  the  chemift  ftiall  bring 
his  glafs  to  perfection. 

The  connexion  between  thefe  two  fciences  is  fo  intimate, 
that  it  is  difhcult  to  draw  a  line  of  dillindlion  between  them. 
If  we  confine  natural  philofophy  to  enquiries  relative  to  the  ex- 
ternal properties  of  bodies,  we  fliall  afford  no  other  object  but 
the  mere  outfide  of  things.  If  we  reftrain  the  chemiiL  to  the 
mere  analyfis,  he  will  at  moft  arrive  at  the  knowledge  of  the 
^onftituent   principles   of    bodies,    and   will    be  ignorant  o: 


PRELIMINARY    DISCOURSE. 


37 


tlieir  fun6lions.  Thefe  diftinc^Ions  in  a  fcience  which 
has  but  one  common  purpoi'e,  namely,  the  complete  knowl- 
edge of  bodies,  cannot  longer  exiil  ;  and  it  appears  to  me 
that  we  ought  abfolutely  to  rejedl  them  in  all  obje£ls  which  can 
only  be  well  examined  by  the  union  of  natural  philofophy  and 
chemiftry. 

At  the  period  of  the  revival  of  letters,  it  was  of  advantage  to  fep- 
arate  the  learned,  as  it  were,  upon  the  road  to  truth ;  and  to  multi- 
ply the  work(hops,if  I  may  ufe  the  expreffion,  to  haften  the  clear- 
ing away.  But  at  prefent,  when  the  various  points  are  re-united, 
and  the  connection  between  the  whole  is  feen,  thefe  feparations, 
thefe  divifions,  ought  to  be  effaced  j  and  we  may  flatter  ourfelves 
that,  by  uniting  our  efforts,  we  may  make  a  rapid  progrefs  in  the 
ftudy  of  nature.  The  meteors,  and  all  the  phenomena  of  which 
the  atmofphere  is.the  grand  theatre,  can  be  known  only  by  this 
re -union.  The  decompofition  of  water  in  the  bowels  of  the 
earth,  and  its  formation  in  the  fluid  which  furrounds  us,  cannot 
but  give  rife  to  the  moft  happy  and  the  moll  fublime  applica- 
tions. 

4.  The  conneclion  between  chemiflry  and  pharmacy  is  fo 
intimate,  that  thefe  two  fciences  have  long  been  confidered  as 
one  and  the  fame  ;  and  chemiflry,  for  a  long  time,  was  culti- 
vated only  by  phyficians  and  apothecaries.  It  mufl  be  allowed 
that,  though  the  chemiflry  of  the  prefent  day  is  very  different 
from  pharmacy,  which  is  only  an  application  of  the  general  prin- 
ciples of  this  fcience,  thefe  applications  are  fo  numerous,  the 
clafs  of  perfons  who  cultivate  pharmacy  is  in  general  fo  well  in- 
formed, that  it  is  not  at  all  to  be  wondered  at,  that  moft  apoth- 
ecaries fhould  endeavour  to  enlighten  their  profefhon  by  a  feri- 
ous  ftudy  of  chemiflry,  and  by  the  happiefl  agreement  unite  the 
knowledge  of  both  parts  of  fcience. 

The  abufes  which,  at  the  beginning  of  the  prefent  century, 
were  made  of  the  applications  of  chemiflry  to  medicine,  have 
caufed  the  natural  and  intimate  relations  of  this  fcience  with  the 
art  of  healing  to  be  miflaken.  It  would  have  been  more  pru- 
dent, no  doubt,  to  have  redlified  its  applications  ;  but  unfortu- 
nately we  have  too  much  ground  to  reproach  phyficians  forgo- 
ing to  extremes.  They  have,  without  reflri6tion,  baniflied 
that  which  they  before  received  without  examination  ;  and  we 
have  feen  them  fuccefhvely  deprive  their  art  of  all  the  afliitance 
it  might  obtain  from  the  auxiUary  fciences. 

In  order  to  diredl  with  propriety  the  applications  of  chemiflry 
to  the  human  body,  proper  views  muft  be  adopted  relating  to 
the  animal  ccoucmy,  together  with  accurate  notions  of  chemif- 


CJ 


S  PRELIMINARY  DISCOURSE. 


try  itfelf.  The  refdlts  of  the  laboratory  mufl  be  confidered  f<,-s 
fubordinate  to  phyfiological  obfervations.  We  ihould  endeav- 
our to  enlighten  the  one  by  the  other,  and  to  admit  no  truth  a« 
eftabliflied  which  h  contradicted  by  any  of  thei'e  means  of  con- 
viClion.  It  is  in  confequence  of  a  departure  from  thefe  prin- 
ciples that  the  human  body  has  been  confidered  as  a  llfciefs  and 
paifive  fubftance  j  and  that  the  (triCt  principles  obferved  in  the 
operations  of  the  laboratory  have  been  applied  to  this  living  fyf- 
tem. 

In  the  mineral  kingdom,  every  thing  iu  fubjeded  to  the  inva- 
riable laws  of  the  aflinities.  No  mternal  principle  modifies  the 
action  of  natural  agents.;  and  hence  it  arifes  that  we  are  capa- 
ble of  foretellmg,  producing  or  modifying  the  efFe(fls, 

In  the  vegetable  kingdom,  the  a6lion  of  external  agents  is  e-- 
qually  evident ;  but  the  internal  organization  modifies  their  ef- 
fects, and  the  principal  functions  of  vegetables  arife  from  the 
combined  aftion  of  external  and  internal  caufes.  It  was  no 
doubt  for  this  reafon  that  the  Creator  difpoied  the  principal  or- 
gans of  vegetation  upon  the  furface  of  the  plant,  in  order  that 
the  various  functions  might  at  the  fame  time  receive  the  impref- 
fions  of  external  agents,  and  that  of  the  internal  principle  of  the 
organization. 

In  animals  the  fun£lions  arc  much  lefs  dependent,  on  exter- 
nal caufes  ;  and  nature  ha-s  concealed  the  principal  organs  ia 
the  internal  parts  of  their  bodies,  as  if  to  withdraw  them  from 
the  influence  of  foreign  powers.  But  the  more  the  functions 
of  an  individual  are  connecSted  with  its  organization,  the  lefs  its 
the  empire  of  chemiftry  over  them  ;  and  it  becomes  us  to  be 
cautious  in  the  application  of  this  fcience  to  all  the  phenomena 
which  depend  efl'entially  upon  the  principles  of  life. 

We  mull  not,  however,  confider  chemillry  as  foreign  to  the 
ftudy  and  practice  of  medicine.     This  fcience  alone  can  teach 
us  the  difficulty  and  art  of  combining  remedies.     This  alone  can 
teach  us  to  apply  them  with  prudence  and   firmnefs.     Without 
the  affiftance  of  this  fcience,  the  praditioner  would  fcarcely  ven- 
ture to  apply  thofe  powerful  remedies  from  which  the  chemical 
phyfician  knows  the  means    of   deriving  fuch    great  advantage. 
Chcmirtry  alone,  in  all  probability,  is  capable  of  affording  means 
of  combating  epidemick  diforders,  which  in  molt  cafes  are  caufed 
by  an  alteration  in   the  air,  the  water,  or  our  food.     It  will  be 
only  in  confequence  of  analyfis    that   the    true   remedy  can  be 
found  againfl   thofe  flony  concretions   which    form  the  matter 
of  the  gout,  the  Hone,  the  rheum atifm,  ^c.  ;  and  the  valuable 
particulars  of  informiation  which  we  now  pcfiefs  refpeding  ref- 
^iratio25,  and  the  nature  of  the  principal  humcurs   cf  the  hu- 


BlELiMINARY   DISCOURSE.  29 

man   body,  are  likevvife  among  the  benefits  arifing  from  this 
fv'lence. 

c.  Chemiftry  is  not  only  of  advantage  to  agriculture,  phyfick> 
mineralogy,  and  medicine,  but  its  phenomena  are  interefting  to 
all  the  orders  of  men  :  the  applications  of  this  fciencc  are  (o 
numerous,  that  there  are  few  circumllances  of  life  in  which  the 
chemifl  does  not  enjoy  the  pleafure  oc  feeing  its  principles  ex- 
emplified. Mofiy;)t  thofc  fa<^s  which  habit  has  led  us  to  view 
with  indiiterence  are  interefting  phenomena  in  the  eyes  of  the 
cliemift.  Every  thing  inlirudls  and  amufes  him  ;  nothing  is  in- 
dlficrent  to  him,  becauTe  nothing  is  foreign  to  his  purfuits  -,  and 
nature,  no  lefs  beautiful  in  her  moll  minute  details  than  fublimc 
in  the  difpof.tion  of  her  general  laws,  appears  to  difplay  the; 
whole  of  her  magnificence  only  to  the  eyes  of  the  chemical  phi- 
iofopher. 

We  might  eafily  form  an  idea  of  this  fcience,  if  it  were  pofTi- 
ble  to  exhibit  in  this  place  even  a  Iketch  of  its  principal  appli- 
cations. We  fhould  fee,  for  ex'ample,  that  chemiflry  affards  us 
all  the  metals  of  which  the  ufes  are  fo  extenfive  ;  that  chemiflry 
affords  us  the  means  of  employing  the  parts  of  animals  and  of 
plants  for  our  ornament  :  that  our  luxuries,  and  our  fubfiftenccj, 
are  by  this  fcience  eilablifhed  as  a  tax  upon  all  created  beings  ; 
and  that  by  this  power  we  are  taught  to  fubjecl  nature  to  our 
wants,  our  tafte,  and  even  to  our  caprices.  ]f  ire,  that  free,  inde- 
pendent element,  has  been  colle£led  and  governed  by  the  induf- 
try  of  the  chemift  ;  and  this  agent,  deflined  to  penetrate,  to  en- 
liven, and  to  animate  the  whole  of  nature,  lies  i^.-  his  hands  be- 
come the  agent  of  death,  and  the  prime  minifterof  deftrucflion. 
The  che mills  who  in  our  time  have  taught  us  to  infulate  that- 
pure  air  which  alone  is  proper  for  combuflion,  have  placed  in 
our  hands,  as  it  were,  the  very  eiTence  of  fire  :  and  this  cle- 
ment, whofe  effii£ls  were  fo  terrible,  becomes  the  agent  of  flili 
more  terrible  confequences.  The  atmofphere,  which  was  form- 
erly confidered  as  a  mafs  of  homo*{eneous  fluid,  is  now  found  to 
be  a  true  chaos,  from  which  analyfis  has  obtained  principles  fo 
much  the  more  interefting  to  he  known,  as  nature  has  made 
tliem  the  principal  agents  of  her  operations.  We  may  confider 
this  mafs  of  fluid  in  which  we  live  as  a  vafl  laboratory,  in  which 
the  meteors  are  prepared,  in  which  aU  the  feeds  of  life  and  death 
are  developed,  from  which .  nature  takes  the  elements  of  the 
compofition  of  bodies,  and  to  wliich  their  fubfequent  decompo- 
fition  returns  the  fame  principles  which  were  before  extra^led. 

Chemiftry,  by  informing  us  of  the  nature  and  principles  of 
bodies,  inftru6\s  us  perfc£ily  concerning  our  relation  to  the  ob- 
jeds  around  us.      Thic  fcicT^re  teaches  u-s,  2$-  it  were,  to  live 


40  PRELIMINARY   DISCOURSE. 

with  them  ;  and  impreflcs  a  true  life  upon  them,  fince  by  this 
means  each  body  has  its  name,  its  chara£ler,  its  ufes,  and  its  in- 
fluence, in  the  harmony  and  arrangement  of  thi's  univerfe. 

The  chemift,  in  the  midft  of  thofe  numerous  beings  'which 
the  common  race  of  men  accufe  nature  of  having  vai;ily  placed 
upon  our  globe,  enjoys  the  profpecft  as  it  were  in  the  centre  of 
a  fociety,  all  whofe  members  are  connected  together  by  inti- 
mate relations,  and  concur  to  promote  the  general  good.  In 
his  fight  every  thing  is  animated,  every  being  performs  a  part 
on  this  vaft  theatre  ;  and  the  chemiil  who  participates  in  thefe 
interefting  fcenes,  is  repaid  with  ufury  for  his  firft  exertions  to 
difcover  the  relations  exifling  between  them. 

We  may  even  confider  this  commerce,  or  mutual  relation 
between  the  chemift  and  nature,  as  very  proper  to  foften  the 
manners,  and  to  imprefs  on  the  charadler  that  freedom  and  tirm- 
iiefs  of  principle  fo  valuable  in  fociety.  In  the  ftudy  of  natural 
hiftory,  no  caufe  ever  prcfents  itfelf  to  complain  of  inconftancy 
or  treachery.  An  attachment  is  eafily  contracted  for  obje(n:s 
which  afford  enjoyment  only  ;  and  thefe  connections  are  as 
pure  as  their  object,  as  durable  as  nature,  and  ftronger  in  pro- 
portion to  the  exertions  which  have  been  required  to  eftablifh 
them. 

From  all  thefe  confiderations,  there  is  no  fclence  which  more 
eminently  deferves  to  enter  into  the  plan  of  a  good  education 
than  chemiftry.  We  may  even  affirm  that  the  ftudy  of  this 
fcience  is  almoft  indifpenfably  neceffary  to  prevent  us  from  being 
Itrangersin  the  midft  of  the  beings  and  phenomena  which  furround 
us.  It  is  true  indeed  that  the  habit  of  beholding  the  objeds  of 
nature  may  produce  a  knowledge  of  fome  of  their  principal  prop- 
erties. We  may  even  in  this  way  arrive  at  the  theory  of  fome  of 
the  phenomena.  But  nothing  is  more  proper  to  check  the  pre- 
tenfions  of  young  perfons,  viho  are  elevated  by  fuch  imperfedt: 
acquifitions,  than  to  (hew  them  the  vaft  field  of  which  they  are 
ignorant.  The  profoundeft  fentiment  of  their  ignorance  will 
be  feconded  by  the  natural  defire  of  acquiring  new  knowledge. 
The  wonderful  properties  of  the  objects  prefented  to  them  will 
engage  their  attention.  The  interefting  nature  of  the  phenom- 
ena will  tend  to  excite  their  curiofity.  Accuracy  of  experiment^ 
and  ftriCtnefs  of  refult,  will  form  their  reafoning  powers,  and 
render  them  fevere  in  their  judgment.  By  ftudying  the  prop- 
erties of  all  the  bodies  which  furround  him,  the  young  fcholar 
learns  to  know  their  relation  with  himfelf  ;  and  by  fucceffively 
attending  to  all  objects,  he  extends  the  circle  of  his  enjoyment 
by^new  conquefts.  He  becomes  a  partaker  in  the  privileges  of 
the  Creator,  by  uniting  and  difuniting,  by  compounding  and  de- 


PRELIMINARY    DISCOURSE.  41 

ftroylng.  "We  might  even  affirm  that  the  Author  of  nature,  re- 
ferving  to  liimfelf  alone  the  knowledge  of  his  general  laws,  has 
placed  man  between  himfelf  and  matter,  that  it  may  receive  thefe 
laws  from  his  hands,  and  that  he  may  apply  them  with  proper 
modifications  and  reftrictions.  In  this  view,  therefore,  we  may 
confider  man  as  greatly  fuperiour  to  the  other  beings  which  com- 
pofe  this  living  fyftcm.  They  all  follow  a  monotonous  and  in- 
variable procefs  ;  receive  the  laws,  and  fubmit  to  effects  without 
modification.  Man  alone  pofleffes  the  rare  advantage  of  know- 
ing a  part  of  thefe  laws,  of  preparing  events,  of  predidling  re- 
fults,  of  producing  efFedls  at  pleafure,  of  removing  whatever  is 
noxious,  of  appropriating  whatever  is  beneficial,  of  compofing 
fubftances  which  nature  herfelf  never  forms ;  and,  in  this  lalt 
point  of  view,  himfelf  a  Creator,  he  appears  to  partake  with  the 
Supreme  Being  in  the  mofl;  eminent  of  his  prerogatives. 


<- 


V 


Elements  of  Chemistry, 


PART  THE  FIRST. 
rCONCERNING  THE  CHEMICAL  PRINCIPLES. 


INTRODUCTION. 

definition  of  Chemiftry  ;  its  Obje(5t  and  Means— Defcriptio-n  of  a  Lab- 
oratory, and  the  principal  Inllruments  employed  in  chemical  Opera- 
jtions,  with  a  definition  of  thqie  Operations. 


(^HEMISTRY  is  a  fcience,  the  objea  of  which  is  to 
afcertain  the  nature  and  properties  of  bodies. 

The  methods  ufcd  to  obtain  this  knowledge  arc  reducible  to 
two  ;  analyfis  and  fynthefis. 

The  principal  operations  of  chemiftry  are  performed  in  a  place 
called  a  Laboratory. 

A  laboratory  ought  to  he  extenfive  and  well  aired,  in  order 
to  prevent  dangerous  vapours  from  remaining,  which  are  pro- 
duced in  fome  operations,  or  which  may  efcapc  by  any  unfore- 
feen  accident.  It  ought  to  be  dry,  becaufe  otherwife  iron  veflels 
would  ruft,  and  moil  of  the  chemical  products  would  be  liable 
to  change.  But  the  principal  excellence  of  a  laboratory  confifts 
in  its  being  furniflied  with  all  thofe  inltruments  which  may  be 
employed  in  the  ftudy  of  the  nature  of  bodies,  and  in  enquiri#$ 
refpefting  their  properties. 

Among  thefe  inltruments  there  are  fome  which  are  of  gen- 
eral ufe,  and  applicable  to  moft  operations  ;  and  there  are  others 
which  fcrve  only  for  peculiar  ufes.  This  divifion  immediately 
points  out  that,  at  the  prefent  inftanf,  we  can  only  treat  of  the 
former,  and  that  we  muft  defcribe  the  others  on  fuch  occafions 
as  will  render  it  neceffary  to  treat  of  their  ufes. 

The  chemical  inftrumcnts  moft  frequently  employed  are  thofe 
which  prefent  themfelves  firft  to  view  upon  entering  a  laborato- 
ty  j  namely,  the  furnaces. 


'44  Evapcratiry  Furnace.     Chemical  VeJJels, 

Thefc  furnaces  confift  of  earthen  veflels  appropriated  to  the 
various  operations  performed  upon  bodies  by  means  of  fire. 

A  proper  mixture  of  fand  and  clay  is  commonly  the  material 
of  which  thefe  vefTels  are  formed.  It  is  difficult,  and  even  im- 
poflible,  to  prefcribe  and  determine,  according  to  any  invariable 
method,  the  proportions  of  thefe  conftituent  parts  ;  becaufe 
they  muft  be  varied  according  to  the  nature  of  the  earth  made 
life  of.  Habit  and  experience  alone  can  furnilh  us  vi^ith  princi- 
ples on  this  fubjedl. 

The  feveral  methods  of  applying  fire  to  fubftanccs  under  ex- 
amination, has  occafioned  the  conftrudlion  of  furnaces  in  differ- 
ent forms,  which  we  (hall  at  pre  fen  t  reduce  to  the  three  follow- 
ing. ^ 

I.  The  evaporatory  furnace. — This  furnace  has  received  its 
name  from  its  ufe.  It  is  ufed  to  reduce  liquid  fubftances  into 
vapour  by  means  of  heat,  in  order  to  feparate  the  more  fixed 
principles  from  thofe  which  are  more  ponderous  ;  and  were 
mixed,  fufpeniied,  compounded,  or  diflblved  in  the  fluid. 

The  fire-place  is  covered  by  the  evaporatory  veflel.  Two  or 
three  grooves,  channels,  or  depreflions  are  made  in  the  fides  of 
the  furnace  near  its  upper  edge,  to  facilitate  the  drawing  of  the 
fire. 

The  velTel  which  contains  the  fubftance  to  be  evaporated,  ig 
called  the  evaporatory  vefiei, 

Thefe  vefTels  are  formed  of  earth,  glafs  or  metal.  VeflHs  of 
unglazed  earth  are  too  porous,  infomuch  that  liquids  filtrate 
through  their  texture.  Thofe  of  porcelain  bifcuit  are  like  wife 
penetrable  by  liquids  flrongly  heated,  and  fufFer  gafeousor  aeri- 
form fubftances  to  efcape.  The  beautiful  experiments  of  Mr. 
D'Arcet  upon  the  combuftion  and  defiruction  of  the  diamond, 
in  balls  of  porcelain,  are  well  known  and  tend  to  illuftrate  this 
fubje£l:.  I  have  confirmed  thefe  refuJts  by  experiments  in  the 
large  way,  upon  the  diflillation  of  aqua-fortis,  which  lofes  as 
■well  in  quality  as  quantity  when  the  proc<fs  is  carried  on  in  vef- 
fels  of  porcelain  clay. 

Glazed  earthen  vefiels  cannot  be  ufed  when  the  glafs  con- 
fiPtS  of  the  calces  of  lead  or  copper  ;  becaufe  thofe  metallick 
matters  are  attacked  by  acids,  fats,  oils,  &c.  Neither  can  earth- 
en vefTels  be  ufed  which  are  covered  with  enamel,  becaufe  this 
kind  of  opaque  glafs  is  almoft  always  full  of  fmall  cracks, 
through  which  the  liquid  would  introduce  itfelf  into  the  body 
of  the  vefiiel. 

Earthen  vefTels  cannot  therefore  be  ufed,  excepting  in  opera- 
tions of  little  delicacy,  in  which  precifion  and  accuracy  are  no^ 
iadifpenfably  required. 


#' 


.Application  of  Heat*  45 

Evaporatory  veflels  of  glafs  are  in  general  to  be  preferred. 
Thofe  which  refill  the  fire  better  thnn  any  others,  are  prepared 

the  laboratory,  by  cutting  a  fphcre  of  glafs  or  a  receiver  into 

o  equal  parts  with  a  red-hot  iron.  The  capfules  which  are 
hiade  in  the  glafs-houfe,  are  thickefl:  at  the  bottom,  and  confe- 
quently  more  liable  to  break  at  that  part  when  expofed  to  the 
iire. 

Evaporatory  veffels  of  metal  are  ufed  in  manufaflories.  Cop- 
per is  moil  commonly  employed,  becaufe  it  not  only  polTeiTes  the 
property  of  refifling  fire,  but  has  a  confiderable  degree  of  folidi- 
ty,  together  with  the  facility  of  being  wrought.  Alembicks  arc 
made  of  this  metal,  for  the  diftillation  of  vinous  fpirits,  and  aro- 
matick  fubftances  j  as  are  alfo  cauldrons  or  pots  for  the  cryllalliza- 
tion  of  certain  falts,  and  for  feveral  dying  proceiTes,  &c.  Lead  is 
likewife  of  confiderable  ufe,  and  is  made  choice  of  whenever  op- 
erations are  to  be  performed  upon  fubftances  which  contain  the 
fulphurick  acid,  fuch  as  the  fulphates  of  alumine  and  of  iron  ; 
and  for  the  concentration  and  redlification  of  the  oil  of  vitrioL 
Tin  veffels  are  alfo  employed  in  Tome  operations  :  the  fcarlet 
bath  affords  a  more  beautiful  colour  in  boilers  of  this  metal  than 
in  thofe  of  any  other.  Capitals  of  tin  have  already  begun  to  be 
fubflituted  in  the  room  of  thofe  of  copper,  in  the  conflrudlion 
of  alembicks  ;  and  by  this  means  the  feveral  produ6ls  of  diftil- 
lation are  exempted  from  every  fufpicion  of  that  dangerous  me- 
tal. Boilers  of  iron  are  likewife  ufed  for  certain  coarfe  opera- 
tions :  as,  for  example,  in  the  concentration  of  the  lixiviums  of 
common  fait,  of  nitre,  &c. 

Evaporatory  veffels  of  gold,  of  filvcr,  or  of  platina,  are  to  be 
preferred  in  fome  delicate  operations ;  but  the  price  and  fcarci- 
ty  of  thefe  veffels  do  not  permit  them  to  be  ufed,  efpecially  ia 
(he  large  way. 

Moreover  it  is  from  the  nature  of  the  fubflance  to  be  evapo- 
rated, that  we  muft  determine  the  choice  of  the  vefTel  mod  fuit- 
nble  to  any  operation.  There  is  no  particular  kind  of  vefiel 
which  can  be  adapted  exclufively  on  all  occafions.  It  may  only 
be  obfervcd,  that  glafs  pre  fen  ts  the  greatefl  number  of  advanta- 
ges, becaufe  it  is  compofed  of  a  fubflance  thje  lead  attacked,  the 
ieall  foluble,  and  the  leafl  deflrudible,  by  chemical  agents. 

Evaporatory  veffels  are  known  by  the  name  of  capfules,  cu- 
curbits, &c.  according  totl>eir  feveral  forms. 

Thefe  veffels  ought  in  general  to  be  very  wide  and  fliallow, 
in  order  that  the  diflillation  and  evaporation  may  be  fpeedy  and 
occonomical.  It  is  neceflary,  i.That  the  evaporatory  vefiel  be 
riot  narrow  at  its  upper  part.  2.  That  the  heat  be  applied  to  the 
3i(|uid  in  all  parts  and  equally.     3.  That  the  column  or  mafs 


4*^  Maths,      Suhlimation, 

t3f  the  liquid  fhould  have  little  depth,  and  a  large  furface  g^ 
evaporation.  It  is  upon  thefe  principles  that  I  have  conftrucled 
in  Languedoc,  boilers  proper  for  diftilling  brandy,  which  favc 
eleven  twelfths  of  the  time,  and  four  fifths  of  the  combuftibles. 

Evaporation  may  be  performed  in  three  manners.  i .  By  a 
Eaked  fire.     2.  By  the  fand  bath.     3.  By  the  water  bath. 

Evaporation  is  made  by  a  naked  fire,  when  there  is  no  fub- 
ftance  interpofed  between  the  fire  and  the  vefiel  which  contains 
the  liquid  intended  to  be  evaporated  ;  as,  for  example,  when 
water  is  boiled  in  a  pot. 

Evaporation  is  performed  by  the  fand  bath,  when  a  vefTdL 
filled  with  fand  is  interpofed  between  the  fire  and  the  evapora- 
tory  veflel.  The  heat  is  in  this  cafe  communicated  more  llowly 
and  gradually  ;  and  the  veflels,  which  would  otherwife  have 
been  broken  by  the  immediate  application  of  the  heat,  are  ena- 
bled to  refift  its  force.  The  heat  is  at  the  fame  time  more 
equally  kept  up  *,  the  refrigeration  is  more  gradual  ;  and  the 
operations  arc  performed  with  a  greater  degree  of  order,  precif- 
ion,  and  facility. 

If,  inftead  of  employing  a  veflel  filled  with  fand,  wc  ufe  a  vef- 
fel  of  water,  and  the  evaporatory  veflel  be  plunged  in  the  li- 
quid, the  evaporation  is  faid  to  be  made  on  the  water  bath  : 
in  this  cafe,  the  fubfliance  to  be  evaporated  is  only  heated  by 
i^mmunication  from  the  water.  This  form  or  method  of  evap- 
oration is  employed  when  certain  principles  of  great  volatility, 
fuch  as  alcohol,  or  the  aromatick  principles  of  plants,  are  to  be 
cxtra£l:ed  or  diftilled.  It  pofl^efl^cs  the  advantage  of  aflx)rding 
produ6ls  vvliich  are  not  changed  by  the  fire,  becaufe  the  heat  is 
tranfmkted  to  them  by  the  intervention  of  a  liquid  :  it  is  this 
eircumdance  which  renders  the  procefs  valuable  for  the  extrac- 
tion of  volatile  oils,  perfumes,  ethereal  liquids,  &:c.  It  poflefles 
the  advantage  of  affording  a  heat  nearly  equal,  becaufe  the  de- 
gree of  ebullition  is  a  term  nearly  conltant ;  and  this  ftandard 
lieat  may  be  graduated  or  varied  at  pleafure,  by  adding  falts  to 
the  liquid  of  the  water  bath,  becaufe  this  Angle  circumftance 
renders  the  ebullition  more  or  lefs  quick  and  eafy.  The  fame 
cfle(ft  may  likewife  be  produced  by  retraining  the  evaporation  ; 
for  in  this  cafe  the  liquid  may  aflume  a  degree  of  heat  much 
iTiore  confiderable,  as  is  feen  in  th€  digefter  of  Papin,  (learn  en- 
gines, eoiipiles,  and  the  boilers  for  ftriking  the  red  tinge  in  cot^ 
ton. 

Sublimation  differs  from  evaporation,  becaufe  the  fubftanc^ 
to  be  raifed  is  foiid.  The  veflels  ufed  in  this  operation  are 
known  by  the  name  of  fublimatory  veflels.  Thefe  arc  com- 
monly globes  terminating  in  a  long  neck  :  they  are  thea  called 
ciattrafles. 


Reverheratory  Furnace,     Retorts*  4^*f 

hi  order  to  fubllme  any  fubflance,  a  part  of  the  ball  of  the 
^attrafs  is  furrounded  with  fand.  The  matter  which  is  volatil* 
ized  by  the  heat,  rifes,  and  is  condenfed  againfl  the  coldeft  part 
)f  the  veflel ;  where  it  forms  a  ftratum  or  cake,  that  may  be  tak- 
rn  out  by  breaking  the  veflel  itfelf.  In  this  manner  it  is  that 
fal  ammoniack,  corrofive  fublimate,  and  other  fimilar  produ<fl;Si 
are  formed  for  the  purpofes  of  commerce. 

Sublimation  is  ufually  performed  either  for  the  purpofe  of 
purifying  certain  fubftances,  and  difengaging  them  from  extra- 
neous matters ;  or  elfe  to  reduce  into  vapour,  and  combine 
under  that  form,  principles  which  would  have  united  with,  great 
difhculty  if  they  had  not  been  brought  to  that  ftate  of  extreme 
divifion. 

II.  The  reverberatory  furnace. — ^The  name  of  the  reverbera- 
tory  furnace  has  been  given  to  that  conftru^lioa  which  is  appro- 
priated to»di  ft  illation. 

This  furnace  is  compofed  of  four  parts.  i.  The  afh-hole, 
intended  for  the  free  paffage  of  the  air,  and  to  receive  the  afhes 
er  refidue  of  the  cumbuftion;  2.  The  fire-place,  feparated 
from  the  afh-hole  by  the  grate,  and  in  which  the  combuftibla 
matter  is  contained.  3.  A  portion  of  a  cylinder,  which  is  called 
the  laboratory,  becaufe  it  is  this  part  which  receive*  the  retorts- 
employed  in  the  operations  or  diftillations.  4.  Thefe  three 
pieces  are  covered  with  a  dome,  or  portion  of  a  fphere,  pierced 
near  its  upper  part  by  an  aperture,  whicL  affords  a  free  paflage 
to  the  current  of  air,  and  forms  a  chimney.  The  moft  ufuat 
form  of  the  reverberatory  furnace  is  that  of  a  cylinder  terminat- 
ed by  a  hemifphere,  out  of  which  arifss  achimney  of  a  greater 
©r  lefs  lengthy,  to  produce  a  fuitable  degree  of  afpiration^ 

In  order  that  a  reverberatory  furnace  may  be  well  propor-^ 
tioned,  it  is  neceflary,  i .  That  the  aih-hole  iliould  be  large,  to 
admit  the  air  frefh  and  unaltered.  2.  That  the  fire-place  and 
laboratory  together  (liould  have  the  form  of  a  true  ellipfis,  whofr 
two  foci  ftiould  be  occupied  by  the  fire  and  the  retort.  la 
this  cafe  all  the  heat,  whether  dired  or  reflecled,  will  ftrike  the 
setort. 

The  reverberatory  furnace  is  ufed  for  diftillatlon,  Diflilla- 
^ion  is  that  procefs  by  which  the  force  of  fire  is  applied  to  dif- 
wnite  and  feparate  the  feveral  principles  of  bodies,  according  t© 
the  laws  of  their  volatility,  and  their  feveral  affinities. 

Diftilling  vefTels  are  known  by  the  name  of  retorts. 

Retorts  are  formed  of  glafs,  of  ftone  ware,  of  porcelain,  or  of 
metal  ;  thefe  fubftances  being  refpe£lively  ufed,  according  to 
the  nature  Qf  \^  bodies  intended  tg  be  .^xpofed  to  diftil*" 
)i^tion. 


45  Receivers.     Forge  Furnace,     Crucibles, 

Whatever  be  tlie  nature  of  the  material,  the  forms  of  re- 
torts are  the  .fame.  This  figure  refembles  an  egg,  terminating 
in  a  beak  or  tube,  which  diminiflies  infenfibly  in  diameter,  and 
is  (lightly  inclined  or  bended. 

The  oval  portion  of  the  retort,  which  is  called  its  belly,  is 
placed  in  the  laboratory  of  the  furnace,  and  is  fupported  upon 
two  bars  of  iron,  which  feparate  the  laboratory  from  the  fire- 
place ♦,  while  the  beak  or  neck  of  the  retort  iffiies  out  of  the 
furnace  through  a  circular  aperture  formed  in  the  edges  of  the 
dome  and  of  the  laboratory. 

A  veflel  intended  to  receive  the  produ£l  of  the  diftillation  is 
fitted  to  the  neck  of  the  retort.  This  velTel  is  called  the  recip- 
ient,  or  receiver. 

The  receiver  is  commonly  a  fphere  with  two  apertures  ;  the 
one  of  confiderable  magnitude,  to  receive  the  neck  of  the  re- 
tort -,  the  other  fmaller,  to  afford  vent  for  the  vapoitrs.  Thi$ 
part  is  called  the  tubulure  of  the  receiv^er  *,  whence  the  terms 
tubulated  receiver,  or  receiver  not  tubulated,  &c. 

Though  the  reverberatory  furnace  be  particularly  adapted  to 
diftillation,  this  operation  may  be  performed  on  the  fand-bath  : 
and  here,  as  in  other  cafes,  it  depends  fingly  on  the  intelligence 
of  the  artift  to  vary  his  apparatus  according  to  the  neceffity  of 
circumftances,  and  the  nature  of  the  fubftances  upon  which  he 
operates. 

The  conftru£lion  o/  thefe  furnaces  may  likewife  be  varied  ; 
and  the  chemift  will  find  it  neceffary  to  learn  the  art  of  availing 
himfelf  of  every  apparatus  he  poffeffes,  to  carry  his  operations 
into  execution :  for  if  he  fhould  perfuade  himfelf  that  it  is  im- 
poffible  to  proceed  in  chemical  refearch,  excepting  in  a  labora- 
tory provided  with  all  fuitable  vefTels  *,  he  may  let  the  moment 
pafs  in  which  a  difcovery  might  be  made,  but  which  may  not 
again  return.  And  it  may  truly  be  faid,  that  he  who  treads 
fcrvilely  in  the  paths  of  others  who  have  gone  before  him,  will 
never  attain  to  the  difcovery  of  new  truths. 

III.  The  forge  furnace. — The  forge  furnace  is  that  in  which 
the  current  of  air  is  determined  by  bellows.  The  afli-hole,  the 
fire-place,  and  the  laboratory  are  here  all  united  together,  and 
this  affemblage  forms  only  a  portion  of  a  cylinder,  pierced  neai< 
the  lower  angle  by  a  fmall  hole,  into  which  the  tube  of  the  bel- 
lows enters.  This  part  is  fometimes  covered  with  a  hemifphere 
or  dome,  to  concentrate  the  heat  with  greater  efficacy,  and  to 
refleclft  it  upon  the  bodies  expofed  to  it.  The  forge  furnace  is 
employed  in  the  fufion  and  calcination  of  metals,  and  generally 
for  all  the  operations  which  ar^  performed  in  crucibles. 

By  crucibles  we  underftand  veffels  of  earth  or  metal,  which 
ire  almoft  always  of  the  form  of  an  inverted  cone.      A  cruci- 


Various  Fuels,     Lutes  and  Coatings  for  Retorts,         49 

tie  ought  to  fupport  the  ftrongefl  heat  without  mehing  :  it 
ought  to  refift  the  attacks  of  ail  fuch  agents  as  are  expofed  to 
heat  veflels  of  this  kind.  Thofe  crucibles  which  pofH^fs  the 
jjreateft  degree  of  perfection,  are  made  in  HeiTe  or  in  Holland. 
I  have  made  very  good  ones  by  a  mixture  of  raw  and  unbaked 
clay  from  Salavas  in  the  Vivarais. 

Our  laboratories  have  been  provided  with  crucibles  of  platina, 
which  unite  the  moth  excellent  properties.  They  are  nearly  in- 
fufible,  and  at  the  fame  time  indeftru^tible  by  the  fire. 

The  feveral  earthen  vefTels  concerning  which  we  have  here 
treated,  may  be  fabricated  by  the  hand,  or  wrought  in  the  lathe. 
The  firft  proceeding  renders  them  more  folid,  the  clay  is  better 
united,  and  it  is  the  only  method  ufed  in  glafs  manufa£lories  ; 
but  the  fecond  method  is  more  expeditious. 

The  agent  of  fuch  decompofitions  as  are  eiFecled  by  means 
of  furnaces,  is  fire.  It  is  afforded  by  the  combuftion  of  wood, 
pit-coal,  or  charcoal. 

Wood  is  only  employed  in  certain  large  works  ;  and  we  pre- 
fer charcoal  in  our  laboratories,  becaufe  it  does  not  fmoke,  has 
no  bad  fmell,  and  burns  better  in  fmall  malFes  than  other  com- 
buflibles.  We  choofe  that  which  is  the  moit  fonorous,  the  dri- 
cit,  and  the  leafb  porous. 

But,  in  the  feveral  operations  we  are  about  to  defcribe,  it  is 
neceffary  to  defend  the  retorts  from  the  immediate  action  of  the 
fire  ;  and  alfo  to  coerce  and  rellrain  the  expanfible  vapours^ 
which  are  very  elaftick,  and  frecjuently  corrcfive.  It  is  to  an- 
fwer  thefe  purpofes  that  various  lutes  are  employed. 

I .  A  glafs  retort  expofed  to  the  adion  of  the  fire  would  in- 
fallibly break,  if  the  operator  were  not  to  have  recourfe  to  the 
iprudent  precaution  of  coating  it  with  earth. 

I  have  found  it  advantageous  for  the  coating  of  retorts,  to 
ufe  a  mixture  of  fat  earth  and  frefh  horfe  dung :  for  this  piir- 
pofe,  the  fat  earth  is  fuffered  to  rot  for  fome  hours  in  water  ;  and 
when  it  is  moiftened,  and  properly  foftened,  it  mu ft  be  kneaded 
with  the  horfe  dung,  and  formed  into  a  foft  paile,  which  is  to 
be  applied  and  fpread  with  the  hand  upon  every  part  of  the  re- 
tort intended  to  be  expofed  to  the  action  of  the  fire.  The  horfe 
dung  combines  feveral  advantages.  i.  It  contains  a  ferous 
fluid,  which  hardens  by  heat,  and  rtrongly  connects  all  the  parts 
together  :  when  this  juice  has  been  altered  by  fermentation  or 
age,  the  dung  does  not  poiTefs  the  fame  virtue.  2.  The  fila- 
ments or  ftalks  of  hay,  which  are  fo  eafily  dilhnguifhed  in  horfvi 
dung,  unite  all  the  parts  of  the  lute  together. 

Retorts  luted  in  this  manner  refift  the  imprefCon  of  the  fire 
very  well  j  and  the  adheficn  of   the  lute  to  the  retort  is  fuch, 
G 


k 


5«  Lutes.     Woulft^s  Apparatus. 

that  even  (liould  the  retort  fly  during  the  operation,  the  diftilla- 
lion  may  be  fllll  carried  on,  as  I  have  daily  experience  In  works 
in  the  large  way. 

2.  When  it  is  required  to  coerce  or  oppofe  the  efcape  of  the 
vapours  which  are"  difengaged  during  any  operation,  it  is  no 
doubt  fufficient  if  the  joinings  of  the  veiTels  be  covered  with 
paper  glued  on,  or  with  flips  of  bladder  moiftened  with  the 
lute  of  lime  and  white  of  Qgg^  provided  the  vapours  be  neither 
dangerous  nor  corrofive  ;  but,  when  the  vapours  are  corrofive, 
it  is  neceflary  to  ufe  the  fat  lute  to  retain  them. 

Fat  lute  is  made  with  boiled  linfeed  oil  mixed  and  well  in- 
corporated with  fifted  clay.  Nut  oil,  kneaded  with  the  fame 
clay,  forms  a  lute  pofieffing  the  fame  properties.  It  iseafily  ex- 
tended in  the  hand,  and  is  ufed  for  defending  the  joinings  of 
velTels,  upon  which  it  is  afterwards  fecured  by  drips  of  linen, 
dipped  in  the  lute  of  lime  and  white  of  egg.  Before  the  appli- 
cation of  heat  in  any  diftillation,  it  is  neceflary  lirlb  to  fufl^er 
the  lutes  to  dry.  Without  this  precautionj  the  vapours  would 
rife  and  efcape  ;  or  other  wife  they  would  combine  with  the 
water  which  moifl:ens  the  lutes,  and  would  corrode  and  dc- 
ilroy  the  bladder,  the  flcin,  the  paper,  and  in  a  word,  every  fub- 
llance  ufed  to  fecure  them  in  their  places.  The  lute  of  lime 
and  the  white  of  egg  dries  very  fpeedily,  and  mufl:  be  ufed  the 
moment  it  is  made.  This  lute,  likewife,  oppofes  the  greated 
lefifliance  to  the  efcape  of  the  vapours,  and  adheres  the  moO: 
intimately  to  the  glafs.  It  is  made  by  mixing  a  fmall  quantity 
of  finely-powdered  quick-lime  with  white  of  egg,  and  after- 
wards beating  up  the  mixture  to  facihtate  the  combination.  It 
mufl:  then  be  inftantly  applied  on  pieces  of  old  linen,  to  be 
wrapped  round  the  places  of  joining. 

In  the  large  works,  where  it  is  not  poflible  to  attend  to  all 
thefe  minute  details,  the  joinings  of  the  retort  and  receiver  are 
luted  together  with  the  fame  lute  which  is  ufed  to  coat  the  re- 
torts.  A  covering  of  the  thicknefs  of  a  itw  lines  is  fuflicient 
to  prevent  the  vapours  of  the  marine  or  nitrous  acid  from  ef- 
caping. 

As  in  certain  operations  a  difengagement  takes  place  of  fo 
prodigious  a  quantity  of  vapours,  that  it  is  dangerous  to  confine 
them  ;  and  as,  on  the  other  hand,  the  fuff'ering  them  to  efcape 
would  occafion  a  confiderable  lofs  in  the  product  ;  an  apparatus 
has  been  contrived  of  great  ingenuity  and  fimplicity  to  moderate 
tlie  ifliie,  and  to  retain  without  rilk  fuch  vapours  as  would  other- 
wife  efcape.  This  apparatus  is  known  by  the  name  of  its  au- 
tlior,  Mr.  "Woulfe,  a  famous  Englifli  chcmifl.  His  mofl:  excel- 
lent procefs  confifl.sin  adapting  the  extremity  of  a  recurved  tube 


Woulfes  Apparatus,  jT 

J  the  tubulure  of  the  receiver  ;  the  other  end  of  which  is  plung- 
ed into  water,  in  a  bottle  half  filled,  and  properly  placed  for  that 
purpofe.  From  the  empty  part  of  tliis  boule  iffues  a  fecond 
tube,  which  is  in  like  manner  plunged  in  the  water  of  a  fecond 
bottle.  A  number  of  other  bottles  may  be  added,  obfcrving  the 
fame  precautions  ;  with  the  attention,  neverthelefs,  to  leave  the 
hit  open,  to  give  a  free  efcape  to  the  vapours  which  are  not  co- 
ercible :  and,  when  the  apparatus  is  thii§  difpofed,  allthejoin- 
""^ngs  are  to  be  luted.  It  will  eafily  be  imagined  that  the  vapours 
which  efcape  from  the  retort  are  obliged  to  pafs  through  the 
tube  adapted  to  the  tubulure  of  the  receiver,  and  confequently 
mufl  pafs  through  the  water  of  the  firft  bottle  :  they  therefore 
fuffer  a  firft  refiftance,  which  partly  condenfes  them.  But  as 
almoft  all  vapours  are  more  or  Icfs  mifcible  and  foluble  in  water, 
a  calculation  is  previoufly  made  of  the  quantity  of  water  necef> 
fary  to  abforb  the  vapours  which  are  difeng^ged  from  the  mix- 
ture in  the  retort  ;  and  care  is  taken  to  diftribute  this  proper 
quantity  of  water  in  the  bottles  of  the  apparatus. 

By  this  means  we  obtain  the  pureft  and  moft  concentrated 
products  ;  becaufe  the  water,  which  is  always  the  receiver, 
and  is  the  vehicle  of  thefe  fubftances,  becomes  faturated  with 
them.  There  is,  perhaps,  no  other  method  of  obtaining  pro- 
ducts always  of  an  equal  energy,  and  comparable  in  their  ef- 
fects ;  a  circumftance  of  the  greateft  importance  in  the  opera- 
tions of  the  arts,  as  well  as  in  philofophical  experiments. 

1  have  applied  this  apparatus  to  works  in  the  large  way  ;  and 
I  ufe  it  to  extract  the  common  muriatick  acid,  the  oxigenated 
jnuriatick  acid,  ammoniack  or  volatile  alkali,  &c. 

As  it  would  very  often  happen,  in  this  apparatus,  that  the 
prefTure  of  the  external  air  would  caufe  the  water  of  the  outer 
veflels  to  pafs  into  the  receiver,  in  confequence  of  the  fimple  re- 
frigeration of  the  retort  ;  this  inconvenience  has  been  obviated, 
by  inferting  a  ftraight  tube  into  the  necks  of  the  firft  and  fecond 
bottles,  to  fuch  a  depth,  that  its  lower  end  is  plunged  into  the 
water,  while  its  other  end  rifes  feveral  inches  above  the  neck  of 
the  bottle.  It  may  eafily  be  conceived,  as  a  confequence  of 
this  difpofition,  that  when  the  dilated  vapours  of  the  receiver 
and  retort  are  condenfed  by  cooling,  the  external  air  will  rufli 
through  thefe  tubes  to  eflablifli  the  equilibrium  \  and  water  can- 
not pafs  from  the  one  to  the  other. 

Before  the  invention  of  this  apparatus,  it  was  ufual  to  drill  a 
hole  in  the  receiver,which  was  kepi:  clofed,  and  only  opened  from 
time  to  time  for  the  efcape  of  the  vapours.  This  method  was  in- 
convenient in  many  refpecSls.  In  the  firft  place,  and  principal- 
ly, becaufe,  in  fpitc  of  all  precautions,  It  was  attended  with  the 


52  iVouIfes  Apparatus,     Balances y  ISc* 

rifk  of  an  explofion  every  moment,  by  the  irregular  difengagc- 
ment  of  the  vapours,  and  the  impoflibillty  of  calculating  tho 
the  quantity  produced  in  a  given  time.  A  fecond  inconven- 
ience was,  that  the  vapours  which  thus  efcaped  occafioned  a 
confiderable  lofs  in  the  produ6l,  and  even  weakened  the  remain- 
der ;  becaufe  this  volatile  principle  confided  of  the  flrongeft 
part.  A  third  inconvenience  was,  that  the  vapours  which  did 
efcape  incommoded  the  artift  to  fuch  a  degree,  that  it  was  im- 
poffible  to  perform  molt  of  the  operations  of  chemiftry  in  the 
courfe  of  a  le(5lure,  where  a  confiderable  number  of  auditors 
were  prefent. 

Thus  it  is  that  the  apparatus  of  Woulfe  unites  a  number  of 
advantages  :  on  the  one  hand,  economy  in  the  procefTes,  and 
fuperiority  in  the  product  \  on  the  other  hand,  fafety  for  the 
chemift  and  his  affiftants  :  and  in  every  point  of  view  the  au- 
thor is  entitled  to  the  beft  acknowledgments  of  chemifts,  who 
were  too  often  fo  much  afFe6led  with  thefe  unwholefome  exhala- 
tions, that  their  health  was  either  totally  deftroyed,  or  they  feii 
abfolute  vi6lims  to  their  zeal  for  the -promotion  of  fcience. 

It  is  neceflary  that  a  laboratory  (hould  be  provided  with  bal- 
ances of  the  utmoft  accuracy  ;  for  the  chemift,  who  very  fre- 
quently operates  only  upon  fmall  quantities,  ought  to  be  able  by 
the  ftridlnefs  of  his  operations,  and  the  accuracy  of  his  appara- 
tus, to  produce  refults  comparable  with  thofe  of  works  in  the 
large  way.  It  frequently  happens  that  the  fimple  eflay  of  a  fpecr- 
men  of  an  ore  determines  the  opening  of  a  mine  :  and  it  fcarcc- 
ly  need  be  pointed  out,  of  how  great  confequence  it  is  to  remove 
every  caufe  of  errour  from  the  operations  of  chemillry  ♦,  fince 
the  flighted  errour  in  the  works  of  the  laboratory  may  be  attend- 
ed with  the  mod  unhappy  confequences,  when  the  application 
of  the  principles  is  made  to  works  in  the  large  way. 

We  {hall  treat  of  other  veil^els  and  of  the  chemical  apparatus,, 
in  proportion  as  we  fhall  have  occafion  to  make  ufe  of  them  i 
for  it  appears  to  us  that,  by  thus  conne£ling  the  defcription  with 
their  ufe,  we  fliall  fucceed  better  in  rendering  them  intelligible 
to  the  reader,  at  the  fame  time  that  his  memory  will  be  lefs  fa« 
tigliied. 


^«//y  of  Jggregai'wn,  53 


SECTION  I. 

:oncerniug  the  General  Law  -whrch  tends  to  bring  the  Particles  of  Bo- 
dies together,  and  to  maintain  them  in  a  State  of  Mixture  or  Com- 
bination. 

JL  HE  Supreme  Being  has  given  a  force  of  mutual  at- 
traftion  to  the  particles  of  matter  ;  a  principle  which  is  alone 
fufficicnt  to  produce  that  arrangement  which  the  bodies  of  this 
univerfe  prefent  to  our  obfervation.  As  a  very  natural  confe- 
quence  of  this  primordial  law,  it  follows  that  the  elements  of 
bodies  muft  have  been  urged  towards  each  other  ;  that  mafles 
mufl  have  been  formed  by  their  re-union;  and  that  folid  and  com- 
padl  bodies  muft  have  infenfibly  been  conftituted  ;  towards 
which,  as  towards  a  centre,  the  lefs  heavy  and  lefs  compadt  bod- 
ies muft  gravitate. 

This  law  of  attra(rHon,  which  the  chemifts  call  Affinity,  tends 
continually  to  bring  principles  together  which  are  disunited, 
and  retains  with  more  or  lefs  energy  thofe  which  are  already  in 
combination  ;  fo  that  it  is  impoffible  to  produce  any  change  in 
nature,  without  interrupting  or  modifying  this  attrad^ive  power. 

It  is  natural,  therefore,  and  even  indifpenfable,  that  we  fliOuld 
fpeak  of  the  law  of  the  affinities  before  we  proceed  to  treat  of  ths 
methods  of  analyfis. 

Affinity  is  exercifed  either  between  principles  of  the  fame  na- 
ture, or  between  principles  of  a  different  nature. 

We  may,  therefore,  diltinguilh  two  kinds  of  affinity,  wirh  re- 
fpeft  to  the  nature  of  bodies,  i.  The  affinity  of  aggrega'Jr.ii, 
or  that  which  exifts  between  two  principles  of  the  fame  nar uve. 
■z.  The  affinity  of  compofition,  or  that  which  retains  two  or 
;nore  principles  of  different  natures  in  a  flate  of  combination. 


OF    THE    AFFINITY    OF    AGGREGATION. 

Two  drops  of  water  v/hich  unite  together  into  one,  form  an 
aggregate,  of  which  each  drop  is  known  by  the  name  of  an  inte- 
grant part. 

An  aggregate  differs  from  a  heap  ;  becaufe  the  integrant  parts 
of  this  laft  have  no  perceptible  adhefion  to  each  other  ;  as,  for 
example,  a  heap  cf  b;;r]ey,  of  fand,  &Cf 


54  Affinity  of  Compo/ltlon, 

An  aggregate  and  a  heap  differ  from  a  mixture  ;  becaufe  the 
conflituent  parts  of  this  laft  are  of  a  different  nature  -,  as,  for 
example,  in  gun-powder. 

The  affinity  of  aggregation  is  flronger,  the  nearer  the  inte* 
grant  parts  approach  to  each  other  ;  fo  that  every  thing  which 
tends  to  feparate  or  remove  thefe  integrant  parts  from  each  other, 
diminifhes  their  affinity,  and  weakens  their  force  of  cohefion. 

Heat  produces  this  effi26l  npon  mod  known  bodies  :  hence 
it  is  that  melted  metals  have  no  confillence.  The  calorick,  or 
matter  of  heat,  by  combining  with  bodies,  aimofl  always  pro- 
duces an  efFe61:  oppofite  to  the  force  of  attrajfiion  ;  and  we 
Kiight  coniider  ourfelves  as  authorized  to  affirm  that  it  is  a  prin- 
ciple of  repulfion,  if  found  chemiflry  had  not  proved  that  it  pro- 
duces this  effect  only  by  its  endeavour  to  combine  witli  bodies, 
and  thereby  neceffarily  diminifli  their  force  of  aggregation,  as  all 
other  chemical  agents  do.  Befides  which,  the  extreme  levity 
of  calorick  produces  the  eife^l  that,  when  it  is  combined  with 
any  given  body,  it  continually  tends  to  elevate  it,  and  to  over- 
come that  force  which  retains  it,  and  precipitates  it  towards  the 
earth. 

The  mechanical  operations  of  pounding,  of  hammering,  or  of 
cutting,  likev/ife  diminifh  the  affinity  of  aggregation.  They  re- 
move the  integrant  parts  to  a  diftance  from  each  other ;  and 
this  new  difpofition,  by  prefenting  a  lefs  degree  of  adhefion, 
and  a  larger  furface,  facilitates  the  immediate  acftion,  and  aug-> 
ments  the  energy,  of  chemical  agents.  It  is  for  this  purpofe 
that  bodies  are  divided  when  they  are  to  be  analyfed,  and  that 
the  effedl:  of  re-agents  is  facilitated  by  the  a£Hon  of  heat. 

The  mechanical  divifion  of  bodies  is  more  difficult,  the  Wrong- 
er their  aggregation. 

Aggregates  exift  under  diiTerent  dates  ;  they  are  folid,  liquid^ 
aeriform,  &c. — See  Fourcroy's  Chemiflry. 

OF    THE    AFFINITY    OF    COMPOSITION. 

Bodies  of  different  kinds  exert  a  tendency  or  attra6lion  upon 
each  other,  which  is  more  or  lefs  ftrong  ;  and  it  is  by  virtue  of 
this  force  that  all  the  changes  of  compofition  or  decompofition 
obferved  amongft  them,  are  effetfled. 

The  affinity  of  compofiiion  exhibits  invariable  laws  in  all  the 
phenomena  it  caufes.  We  may  flate  thcfe  laws  as  general 
principles  ;  to  which  may  be  referred  all  theeffetfls  prefented  to 
our  obfervation  by  the  aQion  of  bodies  upon  each  other. 

I.  The  affinity  of  compofition  a6ls  only  between  the  conflit- 
uent parts  of  bodies. 


Affinity  of  Compofiilon,  ^r 

The  general  law  of  attradlion  is  exerted  upon  the  mafles  j 
nd  in  this  refpe£l  it  differs  from  the  law  of  the  affinities, 
uhich  does  not  perceptibly  afl  but  on  the  elementary  particles 
of  bodies.  Two  bodies  placed  near  each  other  do  not  unite  ; 
but,  if  they  be  divided  and  mixed,  a  combination  may  arife. 
We  have  examples  of  this  when  the  muriate  of  foda,  or  com- 
mon fait,  is  triturated  with  lithrage  ;  the  muriate  ammoniack, 
or  common  fiil  ammoniack,  with  lime,  &c.  And  it  may  be  af- 
ferted  that  the  energy  of  the  affinity  of  compofition  is  almoft  aU 
ways  proportioned  to  the  degree  of  the  divifion  of  bodies. 

II.  The  affinity  of  compofition  is  in  the  inverfe  ratio  of  the 
affinity  of  aggregation. 

It  is  fo  much  the  more  difficult  to  decompofe  a  body,  as  its 
conftituent  principles  ^re  united  or  retained  by  a  greater  force. 
Gafes,  and  efpecially  vapours,  continually  tend  to  combination, 
becaufe  their  aggregation  is  weak  :  and  nature,  which  is  con- 
ftantly  renewing  the  productions  of  this  univerfe,  never  com- 
bines folid  with  folid  ;  but,  reducing  every  thing  into  the  form 
of  gas,  by  this  means  breaks  the  impediments  of  aggregation  j 
and  thefe  gafes  uniting  together,  form  folids  in  their  turn. 

Hence,  no  doubt,  it  arifes,  that  the  affinity  of  compofition  is 
fo  much  the  more  ilrong  as  bodies  approach  nearer  to  the  ele- 
mentary flate  ;  and  we  fhall  obferve,  on  this  fubjeft,  that  this 
law  of  nature  is  founded  in  wifdom  :  for  if  the  force  or  affinity  of 
compofition  did  not  increafe  in  proportion  as  bodies  were  brought 
to  this  degree  of  limplicity  ;  if  bodies  did  not  affiime  a  decided 
tendency  to  unite  and  combine,  in  proportion  as  they  approach 
to  their  primitive  or  elementary  flate  ;  the  mafs  of  elements 
would  continually  increafe  by  thefe  fucceffive  and  uninterrupt- 
ed decompofitions ;  and  we  ffiould  infenfibly  return  again  to 
that  chaos  or  confufion  of  principles,  which  is  fuppofed  to 
have  been  the  original  Hate  of  this  globe. 

The  neceffity  of  this  ftate  of  divifion,  which  is  fo  proper  to 
increafe  the  force  of  affinity,  has  caufed  it  to  be  admitted  as  an 
inconteftiblc  principle,  that  the  affinity  of  compofition  does  not 
take  place,  unlefs  one  of  the  bodies  be  in  a  fluid  ftate  :  corpora 
non  agunt  nift  fmt  Jluida.  But  it  feems  to  me  that  extreme  di- 
vifion might  be  fubftituted  inftead  of  diffi)lution  ;  for  both  thefe 
operations  tend  only  to  attenuate  bodies,  without  altering  their 
nature.  It  is  by  virtue  of  this  divifion,  which  is  equivalent  to 
diffolution,  that  the  decompofition  of  muriate  of  foda  is  effiidled 
by  trituration  with  minium,  as  well  as  the  union  of  cold  and 
dry  alkali  with  antimony,  and  the  difengagement  of  volatile  al- 
kali by  the  fimple  mixture  of  fal  Ammoniack  with  lime. 


^6  Affinity  of  Compofition, 

III.  When  two  or  more  bodies  unite  by  the  afEnity  of  com- 
pofition, their  temperature  changes. 

This  phenomenon  cannot  be  explained  but  by  confidering  the 
fluid  of  heat  as  a  conftituent  principle  of  bodies,  unequally  dif- 
turbed  amongft  them  j  fo  that,  when  any  change  is  produced 
in  bodies,  this  fluid  is  difplaced  in  its  turn,  which  neceflarily 
produces  a  change  of  temperature.  We  fhall  return  to  thefe 
principles  when  we  fpeak  of  heat. 

IV.  The  compound  which  refults  from  the  combination  of 
two  bodies,  pofleifes  properties  totally  different  from  thofe  of  its 
conftituent  principles. 

Some  chemifts  have  affirmed,  that  the  properties  of  com- 
pounds were  intermediate  between  thofe  of  their  conftituent 
parts.  But  this  term  «  intermediate"  has  no  meaning  in  the 
prefent  cafe  ;  for  what  intermediate  qualities  can  exiil  between 
four  and  fweet,  or  between  water  and  fire  ? 

If  we  attend  ever  fo  little  to  the  phenomena  which  are  ex- 
hibited to  us  by  bodies  in  their  compofition,  we  fhall  perceive 
that  their  form,  their  tafie,  and  their  confiftence,  are  changed 
in  combination ;  and  we  cannot  eftablifli  any  rule  to  indicate, 
a  priori^  all  the  changes  which  may  arife,  and  the  nature  and 
properties  of  the  body  which  fliall  be  formed. 

V.  Every  individual  fubftance  has  its  peculiar  affinities  with 
the  various  fubflances  prefented  to  it. 

If  all  bodies  had  the  fame  degree  of  affinity  with  each  other, 
r.o  change  could  take  place  amongfl  them :  we  fhould  not  be 
able  to  difplace  any  principle  by  prefenting  one  body  to  another. 
Nature  has  therefore  wifely  varied  the  affinities,  and  appointed 
to  each  body  its  relation  with  all  thofe  that  can  be  prefented  to  it. 

It  is  in  confequence  of  this  difference  in  the  affinities  that  all 
chemical  decompofitions  are  effecled  :  all  the  operations  of  na- 
ture and  art  are  founded  upon  it.  It  is  therefore  of  importance 
to  be  well  acquainted  with  all  the  phenomena  and  circumftan- 
ces  which  this  law  of  decompofition  can  prefent  to  us. 

The  affinity  of  compofition  has  received  different  names,  ac- 
cording to  its  effedls.  It  is  divided  into  fimple  affinity,  double 
affinity,  the  affinity  of  an  intermedium,  reciprocal  affinity,  &c. 

I.  Two  principles  united  together,  and  feparated  by  means  of 
a  third,  afford  an  example  of  fimple  affinity  :  it  confifts  in  the 
difplacing  of  one  principle  by  the  addition  of  a  third.  Bergman 
has  given  it  the  name  of  Eledive  Attraction. 

The  body  which  is  difengaged,  or  difplaced,  Is  known  by  the 
name  of  the  Precipitate.  An  alkali  precipitates  metals  from 
their  folutions  ;  the  fulphurick  acid  precipitates  the  muriatick, 
the  nitrick,  &c. 


Laios  of  Diampofitlon.     Various  Cafes  of  Affinity         5  f 

The  precipitate  Is  not  always  formed  by  the  dlfengaged  fub- 
ilance.  Sometimes  the  new  compound  itfelf  is  precipitated  ; 
as,  for  example,  when  I  pour  the  fulphurick  or  vitriolick  acid 
on  a  fohition  of  muriate  of  lime.  Sometimes  the  dlfengaged 
body  and  the  new  compound  are  precipitated  together  ;  as,  for 
example,  when  the  fulphate  of  magnefia  or  Epfom  fait  is  difTolv- 
ed  in  water,  and  precipitated  by  means  of  lime-water. 

2.  It  often  happens  that  the  compound  of  two  principles 
cannot  be  deftroyed  either  by  a  third  or  a  fourth  body  feparate- 
ly  applied  ;  but  if  thefe  two  bodies  be  united,  and  placed  in 
contacl  with  the  fame  com.pound,  a  decompofition  or  change  of 
principles  will  then  take  place.  This  phenomenon  coniiltutes 
the  double  aOinity.  An  example  will  render  this  propofition  more 
clear  and  precife.  The  fulphate  of  pot-aOi  or  viti  iolated  tartar 
is  not  completely  decompofed  by  the  nitrick  acid  or  by  lime, 
when  either  of  thefe  principles  is  feparately  prefented  ;  but, 
if  the  nitrick  acid  be  combined  with  lime,  this  nitrate  of  lime 
will  decompofe  the  fulphate  of  pot-afli.  In  this  laft  cafe  the 
affinity  of  the  fulphurick  acid  with  the  alkali  is  weakened  by 
its  affinity  to  the  lime.  This  acid,  therefore,  is  fubjeft  to  two 
attraftions  •,  the  one  which  retains  it  to  the  alkali,  and  the  oth- 
er which  attradls  it  towards  the  lime  :  Mr,  KIrwan  has  named 
the  firft  the  Qu^iefcent  Affinity,  and  the  other  the  Divellant  Af- 
finity. The  fame  may  be  faid  refpedling  the  affinities  of  the 
alkali  ;  it  is  retained  to  the  fulphurick  acid  by  a  fuperlour  force, 
but  neverthelefs  attraiSled  by  the  nitrick  acid.  Let  us  fuppofe, 
now,  that  the  fulphurick  acid  adheres  to  the  alkali  with  a  force 
as  8,  and  to  the  lime  by  a  force  expreffed  by  the  number  6  \ 
that  the  nitrick  acid  adheres  to  the  lime  by  a  force  as  4,  and 
tends  to  pnlte  with  the  alkali  by  a  force  as  7.  It  may  then  be 
perceived  that  the  nitrick  acid  and  the  lime,  feparately  applied 
to  the  fulphate  of  por-afh,  would  not  produce  any  cliange  :  but 

,^  if  they  be  prefented  in  a  ftate  of  combination,  then  the  fulphu- 
^rick  acid  is  attratled  on  the  one  hand  by  6,  and  retained  by  8  ; 
it  has  therefore  an  effi;6live  attracflion  to  the  alkali  as  2.  On 
the  other  hand,  the  nitrick  acid  is  attracfled  by  a  force  as  7,  and 
retained  by  a  force  as  4  ;  it  therefore  retains  a  tendency  to  unite 
with  the  alkali,  which  is  denoted  by  the  number  3  ;  and  coafe- 
quently  it  ought  to  difpiace  the  fulphurick  acid,  which  is  retain- 
ed only  by  a  force  as  2. 

3.  There  are  cafes  in  which  two  bodies,  having  no  percepti- 
ble affinity  to  each  other,  obtain  a  difpofition  to  unite  by  the  in- 
tervention of  a  third  ;  and  this  is  called  the  affinity  of  an  inter- 
medium. An  alkali  is  the  intermedium  of  union  between  oil 
and  water  ;  hence  the  theory  of  lixiviums,  of  wafliings,  8fC.5cc. 


58  Regular  Figures  of  Bodies 

If  the  affinities  of  bodies  were  well  known,  we  might  foretel 
the  refults  of  all  operations  :  but  it  is  obvious  how  difficult  it 
mud  be  to  acquire  this  extenfive  knowledge  of  nature  ;  more 
efpecially  fince  modern  difcoveries  have  exhibited  to  us  an  infin- 
ity of  modifications  in  our  procefles,  and  have  fhewn  that  re- 
fults may  vary  with  fuch  facility,  that  even  the  abfence  or  pref- 
ence  of  light  will  render  them  very  different. 

As  long  as  chemiftry  was  confined  to  the  knowledge  of  a  few 
fubftances,  and  was  bufied  only  in  attending  to  a  certain  num- ' 
ber  of  fa6ls,  it  was  poffible  to  draw  up  tables  of  affinity,  and  to 
exhibit  the  refult  of  our  knowledge  in  one  and  the  fame  table. 
But  all  the  principles  upon  which  thefe  tables  have  been  con- 
ilrucled,  have  received  modifications  ;  the  number  of  principles 
has  increafed  ;  and  we  find  ourfelves  under  the  neceffity  of  la- 
bouring upon  new  ground.  A  fketch  of  this  great  work  may 
be  feen  in  the  Effiiy  on  Affinities  of  the  celebrated  Bergman,  and 
in  article  Affinity  in  the  Ency  dope  die  Methedique, 

VI.  The  particles  which  are  brought  together  and  united  by 
affinity,  whether  they  be  of  the  fame  nature  or  of  different  na- 
tures, continually  tend  to  form  bodies  of  a  polyhedral,  conflant, 
and  determinate  form. 

This  beautiful  law  of  nature,  by  which  fhe  impreffes  on  all  her 
produiflions  a  conflant  and  regular  form,  appears  to  have  been 
unknown  to  the  ancients  :  and  when  chemilts  began  to  difcov- 
er  that  almofl  all  bodies  of  the  mineral  kingdom  affedied  regular 
forms,  they  at  firft  diftinguiffied  them  according  to  the  inaccu- 
rate rcfemblance  fuppofed  to  exifl  between  them  and  other 
known  bodies.  Hence  the  denomination  of  cryftals  in  pyra- 
mids, needles,  points  of  diamonds,  crcfles,  fword  blades,  &c. 

We  are  more  particularly  indebted  to  the  celebrated  Linnaeus 
for  the  firil  precife  ideas  of  thefe  geometrical  figures.  He  took 
notice  of  the  conllancy  and  uniformity  of  this  character  ;  and 
this  celebrated  naturalift  thought  himfelf  authorized  to  make  it 
the  bafis  of  his  method  of  claffification  of  the  mineral  kingdom. 

Mr.  Rome  de  Lille  has  proceeded  ftiU  farther  :  he  has  fubjetfl- 
ed  all  the  forms  to  a  {lri6l  examination  :  he  has,  as  it  were,  de- 
compofed  them  -,  and  is  of  opinion  that  he  can  didinguiffi  iu 
the  cryllals  of  all  analogous  or  identical  fubftances,  the  fimple 
modifications  and  (hades  of  a  primitive  form.  By  this  means 
he  has  reduced  all  the  confufed  and  irregular  forms  to  certain 
primitive  figures  ;  and  has  attributed  to  nature  a  plan  or  primi- 
tive defign,  which  flie  varies  and  modifies  in  a  thoufand  manners, 
according  to  circumflances  that  influence  her  proceedings. 
This  truly  great  and  philofophical  work  has  rendered  this  part 
of  mineralogy   in  the  higheft  degree  interefting  ;    and  if  we 


produced  by  CryjlalUzaUon*  59 

fnould  admit  that  Mr.  De  Lifle  has  perhaps  carried  thefc  refem- 
blances  too  far,  we  cannot  but  allow  that  he  deferves  a  dilUn- 
guilhed  place  amongit  thofe  authors  who  have  contributed  to 
the  progrefs  of  fcience.  The  Cryftallographie  of  this  celebrated 
naturalift  may  be  perufed  with  advantage. 

The  abbe  Hauy  has  fmce  applied  calculation  to  obfervation. 
He  has  undertaken  to  prove  that  each  cryftal  has  a  nucleus  or 
primitive  form  ;  and  has  ihewn  the  laws  of  diminution  to 
which  the  component  lamina  of  the  cryftals  are  fubjedl  in  their 
tranfition  from  the  primitive  to  the  fecondary  forms.  The  de- 
velopement  of  thefe  line  principles,  and  their  application  to 
cryftals  the  beft  known,  may  be  feen  io  his  theory  of  the  ftrucSt- 
ure  of  cryftals,  and  in  fcveral  of  his  memoirs  printed  in  the  vol- 
umes of  the  Academy  of  Sciences. 

The  united  labours  of  thefe  celebrated  naturalifts  have  carri- 
ied  chryftallography  to  a  degree  of  perfedlion  of  which  it  did 
not  appear  fufceptible.  But  we  fhall,  at  this  moment,  attend 
only  to  the  principles  according  to  which  cryftallization,  is 
efFeded. 

To  difpofe  a  fubftance  to  cryftallization,  it  is  neceflary  in  the 
firft  place  to  reduce  it  to  the  moft  complete  ftate  of  divifion. 

This  divifion  may  be  effedled  by  folution,  or  by  an  operation 
purely  mechanical. 

Solution  may  be  effecl:ed  either  by  the  means  of  water  or  of 
fire.  The  folution  of  falts  is  in  general  performed  in  the  firft 
liquid,  that  of  metals  is  effected  by  means  of  the  fecond  ;  and 
their  folution  is  not  complete  until  a  degree  of  heat  is  applied 
of  fufficient  intenfity  to  convert  them  into  the  ftate  of  gas. 

When  the  water  which  holds  any  fait  in  folution  is  evaporat- 
ed, the  principles  of  the  diffolved  body  are  infenfibly  brought 
nearer  to  each  other,  and  it  is  obtained  in  regular  form.  The 
fame  circumftance  nearly  takes  place  in  the  folution  by  fire. 
When  a  metal  is  impregnated  with  this  fluid,  it  does  not  cryf- 
allize  but  in  proportion  as  this  excefs  of  igneous  fluid  is  with- 
drawn. 

In  order  that  the  form  of  a  cryftal  may  be  regular,  three  cir- 
cumftances  are  required  ;  time,  a  fufficient  fpace,  and  repofe. 
Confult  Linnreus,  Daubenton,  &c. 

A.  Time  caufes  the  fuperabundant  fluid  to  be  flowly  diflipat- 
ed,  and  brings  the  integral  parts  nearer  each  other  by  infcnfible 
gradation,  and  without  any  fudden  fliock.  Thefe  integrant 
parts  therefore  unite  according  to  their  conftant  laws,  and  form 
a  regular  cryftal.  For  this  reafon  it  is,  that  flow  evaporation  is 
recommended  by  all  good  chemifts.  Vide  Stahl's  Treatifc  on 
falts,  chap.  29. 


6o  Various    Appearances 

In  proportion  as  the  evaporation  of  the  folvent  is  efFcded,  the 
principles  of  the  diflblved  body  approach  each  other,  and  their 
affinity  is  contiually  augmented  while  that  of  the  folvent  remains 
unaltered.  Hence  it  arifes,  no  doubt,  that  the  lait  portions  of 
the  folvent  are  moft  difncultly  volatilized,  and  that  falts  retain  a 
greater  or  lefs  quantity,  which  forms  their  water  of  cryftalliza- 
tion.  The  proportion  of  water  of  cryftallization  not  only  varies 
greatly  in  the  different  falts,  but  it  adheres  with  greater  or  lefs 
flrength.  There  are  fome  which  fuffer  this  water  to  fly  off 
when  they  are  expofed  to  the  air ;  fuch  as  foda  or  the  mineral 
alkali,  the  fulphate  of  foda  or  Glauber's  fait,  &c.  In  this  fitu- 
ation  thefe  falts  lofe  their  tranfparency,  and  fall  into  powder  : 
they  are  then  faid  to  have  efflorefced.  There  are  other  falts 
which  obftinately  retain  their  water  of  cryftallization  ;  fuch  as 
the  muriate  of  pot-a(h,  the  nitrate  of  pot-afh  or  common 
nitre,  &c. 

The  phenomena  prefented  to  us  by  the  different  falts,  when 
forcibly  deprived  of  their  water  of  cryftallization,  exhibit  other 
varieties.  Some  crackle  with  the  heat,  and  are  thrown  about  in 
fmall  pieces  when  the  water  is  diffipated  :  this  appearance  is 
called  decrepitation.  Others  emit  the  fame  water  in  the  form 
of  fleam,  and  are  liquefied  with  a  diminution  of  their  bulk. 
Others  again  fwell  up,  and  become  converted  into  a  bliftered  or 
porous  fubftance. 

We  are  indebted  to  Mr.  Kirwan  for  an  accurate  table  of  the 
"Water  of  cryftallization  contained  in  each  fait.  This  table  may 
be  feen  by  confulting  his  Mineralogy. 

The  fimple  cooling  of  the  fluid  which  holds  the  fait  in  folu- 
tion  may  precipitate  a  confiderable  quantity.  The  calorick  and 
the  water  diffolve  a  greater  quantity  of  fait  when  their  action  is 
united  ;  and  it  may  ealily  be  imagined  that  the  fubtradion  of 
one  of  the  folvents  muft  occafion  the  precipitation  of  that  por- 
tion which  it  held  in  folution.  Thus  it  is  that  warm  water 
faturated  with  fait,  muft  fuffer  a  part  to  precipitate  by  cooling  ; 
and  for  this  reafon  cryftallization  alvvays  begins  at  the  furfaceof 
the  liquid,  and  on  the  fides  of  the  containing  veffel ;  namely,  be- 
caufe  thefe  parts  are  the  firft  which  fufier  refrigeration. 

It  is  the  alteration  of  heat  and  cold  which  caufes  the  atmof- 
phere  to  diffolve  fometimes  a  greater^  and  fometimes  a  lefs  quan- 
tity of  v/ater  ;  and  conftitutes  mifts,  the  evening  dew,  &c. 

The  mutual  approach  of  the  conftituent  parts  of  a  body  held 
in  folution  may  be  likewife  accelerated  by  prefenting  to  the  wa- 
ter which  fufpends  them,  another  body  which  has  a  ftronger  af- 
finity to  it.  It  is  upon  th^s  principle  that  alcohol  precipitates  fev-* 
eral  falts. 


attending  CryJIa/Iizationy    Id'c,  6 1 

B.  Space  or  fufficient  room  is  likewlfe  a  condition  ncceffary 
for  obtaining  regular  cryftallization.  If  nature  be  reftrained  in 
her  operations,  the  product  of  her  labour  will  exhibit  fymptoms 
of  this  (tate  of  conftraint.  It  may  be  afferted  that  nature  forms 
her  produdlions  according  to  all  the  circumftances  which  may 
influence  her  operations. 

C.  A  (tate  of  repofe  in  the  fluid  is  like  wife  necefTary  to  obtain 
very  regular  forms.  Uninterrupted  agitation  oppofcs  all  fym- 
metrical  arrangement  ;  and  in  this  cafe  the  cryftallization  obtain- 
ed will  be  confufed  and  indeterminate. 

I  am  perfuaded  that,  in  order  to  obtain  bodies  under  the  form 
of  cryftals,  a  previous  folution  is  not  necefi'ary,  but  that  a  fimple 
mechanical  divifion  would  be  fufllicient.  To  obtain  a  convichon 
of  this  truth,  it  is  only  neceflary  to  obferve  that  folution  does 
not  change  the  nature  of  bodies,  but  fimply  procures  an  extreme 
ftate  of  divifion  ;  fo  that  the  difunited  principles  approaching 
each  other  very  gradually,  and  without  flarts,  can  adapt  them- 
felves  to  each  other,  by  following  tlie  invariable  laws  of  their 
gravity  and  affinity.  Now  a  divifion  purely  mechanical  produces 
the  fame  efFeft,  and  places  the  principles  in  the  fame  difpofi- 
tion.  We  ought  not  therefore  to  be  furprlzed  if  mofb  lalts, 
fuch  as  gypfum,  when  difperfed  in  the  earth,  fhould  afliime  reg- 
ular forms  without  any  previous  folution  ;  neither  ought  we 
to  think  it  ftrange  if  the  imperceptible  fragments  of  quartz, 
of  fpar,  &c.  when  carried  along  and  prodigioufly  divided  by  the  ac- 
tion of  waters,  fliould  be  depolited  in  the  form  of  regular  cryftals. 
A  very  fmgular  property  may  be  obferved  in  falts  ;  Mhich 
may  be  referred  to  cryftallization,  but  is  likewife  in  fome  meafurc 
remote  from  it,  becaufe  it  does  not  depend  uj^on  the  fame 
caufes.  This  is  the  property  of  rifmg  along  the  fides  of  the  vef- 
fels  which  contain  the  folution.  It  is  known  by  the  name  of 
Saline  Vegetation. 

I  have  firft  demonftrated  that  this  phenomena  depends  on  the 
<:oncurrence  of  air  and  light  ;  and  that  the  elTecl:  may  be  deter- 
mined at  pleafure  towards  any  part  of  the  veflel,  by  managing 
-nd  directing  the  aclion  of  thefe  two  agents. 

I  have  fliewn  the  principal  forms  which  this  fmgular  vegeta- 
tion afte6\s.  The  detail  of  my  experiments  may  be  feen  in  the 
third  volume  of  the  Memoirs  of-  tlie  Academy  of  Touloufe. 

Mr.  Dorthes  has  confirmed  my  refults  ;  and  has  moreover 
obferved  that  camphor,  fpirits  of  wine,  water,  Z<c.  which  rife  by 
infcnfible  evaporailon  in  half-filled  veftels,  ccnftnntly  attach 
themfelves  to  the  moft  enlightened  parts  of  the  vcilcls. 

Mellrs.  Petit  and  Rouelie  have  treated  on  the  vegetation  of 
falts  ;  but  a  feries  of  experiments  on  the  fubjedl  was  wanting. 
This  is  what  we  have  endeavoured  to  fupply. 


6 1     Methods  of  feparatitig  the  component  Parts  of  Bodies , 

SECTION     II. 

Concerning  the  various  Means  employed  by  Chemifls  to  overcome  the 
Adhefion  v^hich  exifts  between  tJie  Particles  of  Bodies. 


X  HE  law  of  affinities,  towards  which  our  attention  has 
been  directed,  tends  continually  to  bring  the  particles  of  body 
into  contaft,  and  to  maintain  them  in  their  flate  of  union.  The 
efforts  of  the  chemift  are  alnioft  all  directed  to  overcome  this 
attra£live  power,  and  the  means  he  employs  are  reducible  to — 
I.  The  divifion  of  bodies  by  mechanical  operations.  2.  The 
divifion  or  feparation  of  the  particles  from  each  other  by  the  af- 
fiftance  of  folvents.  3.  The  means  of  prefenting  to  the  feveral 
principles  of  the  fame  bodies,  fubftances  which  have  a  ftronger 
affinity  to  them  than  thofe  principles  have  to  each  other. 

I.  The  different  operations  performed  upon  bodies  by  the 
chemift,  to  determine  their  nature,  alter  their  form,  their  tex- 
ture, and  even  in  fome  inftances  change  their  conftitution.  All 
thefe  changes  are  either  mechanical  or  chemical. 

The  mechanical  operations  we  fhall  at  prefent  defcribe,  do 
not  change  the  nature  of  fubftances,  but  in  general  change  only 
their  form  and  bulk.  Thefe  operations  are  performed  by  the 
hammer,  the  knife,  the  peftle,  &c.  Whence  it  follows,  that 
the  chemical  laboratory  ought  to  be  provided  with  all  thefe  in- 
ftruments. 

Thefe  divifions  or  triturations  are  performed  in  mortars  of 
ftone,  of  glafs,  or  of  metal.  It  is  the  nature  of  the  fubftance  un- 
der examination  which  determines  the  ufe  of  one  or  the  other 
of  thefe  veffels. 

The  objed:  of  this  preliminary  operation  is,  to  prepare  and 
difpofe  bodies  for  new  operations  which  may  difunite  their  prin- 
ciples and  change  their  nature  ;  thefe  laft-mentioned  operations, 
which  may  be  diftingulfned  by  the  appellation  Chemical,  are 
what  molt  effentially  conftitute  the  analyfis. 

II.  The  folution  to  which  we  are  at  prefent  to  attend,  confift^ 
in  the  divifion  and  difappearance  of  a  folid  in  a  liquid,  but  with- 
out any  alteration  in  the  nature  of  the  body  fo  diflblved. 

The  liquid  in  which  the  folid  difappears,  is  called  the  folvent 
or  menftruum. 

The  agent  of  folution  appears  to  follow  certain  conftantlaws^ 
which  we  (hall  here  point  out. 


i 


Phenomena  of  Soluiiofi*  63 

A.  The  agent  of  folution  does  not  appear  to  differ  from  that 
of  affinity  ;  and  in  all  cafes* the  folution  is  more  or  lefs  abundant, 
the  greater  the  affinity  of  the  integrant  parts  of  the  folvent  is  to 
thofe  of  the  body  to  be  diflblved* 

From  this  principle  it  follows,  that,  to  facilitate  folution,  it  is 
neceflary  that  bodies  fhould  be  triturated  and  divided.  By  this 
means  a  greater  number  of  furfaces  are  prefented,  and  the  affini- 
ty of  the  integrant  parts  is  diminifhed. 

It  fometimes  happens  that  the  affinity  between  the  folvent 
and  the  body  prefented  to  it  has  fo  little  energy,  that  it  does 
not  become  perceptible  till  after  a  confiderable  interval  of  time. 
Thefe  flow  operations  of  which  we  have  fome  examples  in  our 
laboratories,  are  common  in  the  works  of  nature;  and  it  is 
probably  to  fimilar  caufes  that  we  ought  to  refer  moft  of  thofe 
refults  whofe  caufes  or  agents  efcape  our  perception  or  obferva- 
tion. 

B.  Solution  is  more  fpeedy  in  proportion  as  the  body  to  be 
difTolved  prefents  a  greater  furface  :  on  this  principle  is  founded 
the  pra(Slice  of  pounding,  triturating,  and  dividing  bodies  intend- 
ed to  be  difTolved.  Bergman  has  even  obferved,  that  bodies 
which  are  not  attacked  in  confiderable  mafles,  become  folubie 
after  minute  divifion.    Letters  on  Iceland,  p.  421.* 

C.  The  folution  of  a  body  conftantly  produces  cold.  Ad^ 
vantage  has  ever  been  taken  of  this  phenomenon  to  procure  arti- 
ficial cold,  much  fuperiour  to  the  moft  rigorous  temperature  ever 
obferved  in  our  climates.  We  (hall  again  advert  to  this  princi- 
ple when  we  come  to  treat  of  the  laws  of  heat. 

The  principal  folvents  employed  in  our  operations  are  water, 
alcohol,  and  fire.  Bodies  fubmitted  to  one  or  the  other  of  thefe 
folvents  prefent  fimilar  phenomena  ;  they  are  divided,  rarefied, 
and  at  laft  difappear  j  the  moft  refractory  metal  melts,  is  dif- 
fipated  in  vapour,  and  paffes  to  the  ftate  of  gas,  if  a  very  ftrong 
heat  be  applied  to  it.  This  laft  ftate  forms  a  complete  folution 
of  the  metallick  fubftance   in  the  calorick. 

The  effect  of  calorick  is  often  united  with  one  of  the  other 
folvents,  to  accomplifh  a  more  fpeedy  and  abundant  folution. 

The  three  folvents  here  mentioned  do  not  exercife  an  equal 
a£lion  on  all  bodies  indifcriminately.  Skilful  chemifts  have  ex- 
hibited tables  of  the  diiTolving  power  of  thefe  menftruums.  We 
may  fee,  in  the  mineralogy  of  Kirwan,  with  what  care  that  cel- 
ebrated chemift  has  exhibited  the  degree  of  folubility  of  each 
fait  in  water.     The  table  of  Mr.  De  Morveau  may  like  wife  be 

*  Von  Troll's  Letters,  quoted  by  Mr.  Bergman.     T, 


64  Effecis  of  Re- Agents, 

confulted  on  the  dilToIving  power  of  alcohol.     Journal  de  Plij'- 
fiquc,  1785. 

Moil  autliors  who  have  treated  of  folutlon  have  confidered  it 
in  too  mechanical  a  point  of  view.  Some  have  fuppofed  flieaths 
in  the  folvent,  and  points  in  the  body  diiTolvcd.  This  abfurd 
and  gratuitous  fappofition  has  appeared  fufficient  to  account  for 
the  action  of  acids  upon  bodies.  Newton  and  Gaflendi  have 
admitted  pores  in  water,  in  which  falts  might  infinuate  ihem- 
felves  ;  and  have  by  this  means  explained  why  water  does  not 
augment  in  its  bulk  in  proportion  to  the  quantity  of  fait  it  takes 
up.  Geflendi  has  even  fuppofed  pores  of  different  forms  ;  and 
has  endeavoured  to  fliew  by  this  means  how  water  faturated 
with  one  fait  may  diffolve  others  of  another  kind.  Dr.  Watfon, 
who  has  obferved  the  phenomena  of  folution  with  the  greateft 
care,  has  concluded  from  his  numerous  experiments  *,  i.  Thar 
the  water  rifes  in  the  veflel  at  the  moment  of  the  immerfion  of 
the  fait.  2.  That  it  falls  during  the  folution.  3.  That  it  rifes 
after  the  folution  above  the  original  level.  The  two  laft  efFecls 
feem  to  me  to  arife  from  the  change  of  temperature  which  the 
liquor  undergoes.  The  refrigeration  arifing  from  the  folution 
muft  diminifh  the  volume  of  the  folvent ;  but  it  ought  to  return 
to  its  firft  ftate  as  foon  as  the  diflblution  is  finifhed.  The  tables 
of  Dr.  Watfon  refpe6ling  thefe  phenomena,  and  the  fpecitick 
gravity  of  water  faturated  with  different  falts,  may  be  confulted 
in  the  Journal  de  Phyfique,  vol.  xiii.  p.  62.* 

III.  As  the  peculiar  affinities  of  bodies  to  each  other  are  vari- 
ous, the  conftituent  principles  may  be  eafily  difengaged  by  other 
fubftances  ;  and  it  is  upon  this  confideration  that  the  adtion  of 
all  the  re-agents  employed  by  chemiftry  in  its  analyfis  is  found- 
ed. Sometimes  the  chemifh  difplaces  certain  principles,  which 
lie  can  in  that  ftate  examine  more  accurately,  becaufe  infulated, 
and  difengaged  from  all  their  combinations.  It  frequently  hap- 
pens that  the  re-agent  made  ufe  of  combines  with  fome  princi- 
ple of  the  body  analyfed  ;  and  a  compound  arifes,  whofe  char- 
a6lers  indicate  to  us  the  nature  of  the  principle  which  has  thus 
entered  into  combination,  becaufe  the  combinations  of  the  prin- 
cipal re-agents,  v.-ith  various  bafes  are  well  known.  It  iikewife 
frequently  happens  that  the  re-agent  made  ufe  of  is  itfelf  decom- 
pofed,  which  circumltance  renders  the  phenomena  and  the 
products  more  complicated  ;  but  we  are  enabled  from  the  na- 
ture of  thefe  products  to  form  a  judgment  of  the  component 
parts  of  the  body  analyfed.  This  laft  fadt  was  little  attended  to 
by  the  ancient  chemifts  j  and  this  is  one  of  the  principal  defeiTis 

'  *-0r  in  tht  fiftli  vol.  of  his  Clicmical  ElTavs.      T. 


i 


Method  of  Studying  the  Science  of  Chemj/iry.  65 

of  the  labours  of  Stahl,  who  has  referred  mofl:  of  thofe  phenom- 
ena to  the  bodies  which  he  fubmitted  to  analyfis,  which  in  re- 
ality arofe  only  from  the  decompofition  of  the  re-agents  employ- 
«d  in  his  operations. 


SECTION  III. 

Concerning  the  Method  of  Proceeding  which  the  Chemift  ought  to  foL 
low  in  the  Study  of  the  various  Bodies  prefented  to  us  by  Nature. 


X  HE  progrefs  made  in  any  faience  depends  upon  the 
tolidity  of  thofe  principles  which  forn^^its  bafis  and  upon  the 
method  of  ftudying  them.  It  is  not,  therefore,  to  be  wondered 
at,  that  chemiftry  made  but  little  progrefs,  in  thofe  times,  when 
the  language  of  chemifts  was  enigmatical,  and  when  the  princi- 
ples of  the  fcience  were  founded  only  on  analogies  falfely  de- 
duced, or  on  a  few  fafls  illy  underftood.  In  the  times  which 
have  followed  this  epocha,  the  fa<fls  have  indeed  been  more  at- 
tended to  \  but,  inftead  of  fufFering  them  to  fpeak  for  themfelves 
chemifts  have  been  defirous  of  making  applications,  drawing 
confequences,  and  eftablifhing  theories.  Thus  it  was  that  Stahl, 
when  he  firfl:  obferved  that  oil  of  vitriol  and  charcoal  produced 
fulphur,  if  he  had'then  confined  himfelf  to  the  fimple  relation  o£ 
the  fadt,  he  would  have  announced  a  valuable  and  eternal  truth  ; 
hut  when  he  concluded  that  the  fulphur  was  produced  by  the 
combination  of  the  inflammable  principle  of  the  charcoal  with 
the  oil  of  vitriol,  he  aflerted  that  which  the  experiment  does  not 
point  out  :  then  it  was  that  he  proceeded  further  than  the  fa£ls 
warranted  ;  and  this  firft  ralh  ttep  might  be  a  firft  (lep  towards 
errour.  All  doifkrinej  in  order  to  be  laftingj  ought  to  confift  of 
the  pure  and  fimple  expreffion  of  fa£ts  :  but  we  are  almoft  al. 
wayy  governed  by  our  imaginations  ;  we  adapt  the  fadls  to  our 
manner  of  feeing  them,  and  thus  we  are  milled  by  ourfelves. 
The  prejudice  of  felf-love  afterwards  furnifties  us  with  various 
means  to  avoid  recantation  ;  we  exert  ourfelves  to  draw  our 
fuccefibrs  into  the  fame  paths  of  errour  ;  and  it  is  not  till  after 
much  time  has  been  loft,  after  many  vain  conjectures  have  been 
exhibited,  and  after  we  have  the  ftrongeft  convictions  that  it  is 
impcflible  to  bend  tl\c  nature  of  things  to  our  caprices  and  un- 


66  Method  of  Studying 

founded  ideas,  thnt  fpme  fuperiour  mind  difengages  itfelf  frorri 
the  dclufion  ;  and  returning  to  experiment,  and  the  nature  cf 
things,  fuffers  himfelf  to  be  led  no  further  than  he  is  authorized 
by  thefe  to  proceed. 

We  may  affirm,  16  the  honour  of  our  contemporaries,  that 
fads  are  at  prefent  difcufTed  by  a  much  feverer  logick  ;  and  it 
is  to  this  vigorous  method  of  invelligation  and  difcuflion  that  we 
are  indebted  for  the  rapid  progrefs  of  chemiRry.  It  is  in  con^ 
fequenc^  of  this  dialeclick  march  that  we  have  at  length  arrived 
to  the  pra£lice  of  attending  to  all  the  principles  which  are  com- 
bined or  difengaged  in  the  operations  of  nature  and  art.  We 
keep  an  account  of  all  the  circumftances  which  have  a  more  or 
lefs  confiderable  influence  on  the  refults,  and  we  deduce  fimple 
and  natural  confequences  from  the  whole  of  the  facts  *,  by  which 
means  we  create  a  fcience  as  ftri(Sl:  in  its  principles  as  fublime 
in  its  appHcations. 

This  then  is  the  moment  to  draw  out  a  faithful  fketch  of  the 
aflual  ftate  of  chemiflry,  and  to  colle£):  in  the  numerous  writ- 
ings of  modern  chemifts  every  thing  which  may  ferve  to  lay  th^ 
foundation  of  this  beautiful  fcience. 

Not  many  years  ago,  it  was  poffible  to  prefent,  in  a  few 
words,  the  whole  of  our  knowledge  of  chemiftry.  It  was  fuf- 
ficient  at  that  time,  to  point  out  the  methods  of  performing 
pharmaceutical  operations  ;  the  procefTes  of  the  arts  were  almoft 
all  enveloped  in  darknefs,  the  phenomena  of  nature  were  all 
enigmatical  ;  and  it  is  only  fince  this  veil  has  begun  to  be  re- 
moved that  we  have  beheld  the  developement  of  a  c6lle£lion  of 
fafts  and  refearches  referable  to  general  principles,  and  forming 
a  fcience  entirely  r\tw.  Then  it  was  that  a  number  of  men  ot 
genius  reviewed  the  whole,  and  attended  to  the  improvement 
of  chemical  knowledge.  Every  ilep  in  their  progrefs  brought 
them  nearer  to  the  truth  ;  and  in  a  few  years  we  have  beheld 
a  perfpicuous  do£^rine  arife  out  of  the  ancient  chaos.  Every 
event  has  appeared  conformable  to  the  laws  they  eftabliftied  ; 
and  the  phenomena  of  art  and  natu^re  are  now  explained  with 
equal  facility. 

But  in  order  to  advance  with  fpeed  in  the  career  which  has 
been  thus  opened,  it  is  necell'iry  to  explain  certain  principles, 
according  to  which  we  may  direil  our  lleps. 

In  the  firft  place,  I  think  it  proper  to  avoid  that  tedious  cuf- 
tom  which  fubjecfts  the  beginner  in  any  fcience  to  the  painful 
talk  of  colle£iing  all  the  opinions  of  various  philofophers  before 
he  decides  for  himfelf.  In  reality,  facfts  belong  to  all  times,  and 
are  as  unchangeable  as  nature  herfelf,  whofe  language  they  are. 
0ut  the  confequences  deduced  from  them  nvuft  vary  according 


the  Science  ofCkemifiry,  .^7 

^^o  the  ftate  of  oiir  acquired  knowledge.  It  is  eternally  true  for 
example,  that  the  combuRion  of  fulphur  affords  the  fulphurick 
acid.  It  was  believed,  for  a  certain  time,  that  this  acid  was 
contained  in  the  fulphur  ;  but  our  difcoveries  on  the  combuf- 
tion  of  bodies  ought  to  have  led  us  to  the  dedudion  of  a  very 
different  theory  from  that  which  prefented  itfelf  to  the  earliell 
chemifts.  Wc  ought,  therefore,  to  attach  ourfelves  principally 
^to  facls  j  or  rather  we  ought  to  attach  ourfelves  to  the  fadls  only, 
becaufe  the  explanation  which  is  given  of  them  at  remote  times 
is  very  feldom  fuited  to  the  prefent  Itate  of  our  knowledge. 

The  numerous  fads  with  which  chemiftry  has  been  fucccf^ 
fively  enriched,  form  the  firft  embarraflment  of  the  fludent  who 
is  defirousof  acquiring  the  elements  of  this  fcience.  In  fa£l, 
what  are  the  elements  of  a  fcience  ?  The  clear,  fimple,  and  ac- 
curate enunciation  of  thofe  truths  which  form  its  bafis.  It  is 
neceflary,  therefore,  for  the  full  accomplilhment  of  this  purpofe, 
to  analyfe  all  the  fa6ls,  and  to  exhibit  a  faithful  and  clear  abridg-, 
ment :  but  this  method  is  impracticable  on  account  of  the  nu- 
merous details,  and "  the  infinite  number  of  difcuffions,  into 
which  it  would  lead  us.  The  only  proceeding,  therefore,  Vv^hich 
appears  to  me  to  be  pradicable,  is  to  exhibit  the  moil  decifive 
experiments,  thofe  which  are  the  lead  contefted,  and  to  neg^edt 
thofe  which  are  doubtful  or  inconclufive  :  for  one  experiment, 
well  made,  eftabHflies  a  truth  as  inconteftibly  as  a  thoufa|i4 
equally  averred. 

When  a  propofition  is  found  to  be  fupported  by  fufpicious  or 
contefted  fads,  when  oppofite  theories  are  built  upon  contra- 
dictory experiments,  we  mull:  have  the  courage  to  difcufs  them, 
to  repeat  them,  and  to  acquire  a  certainty  of  the  truth  by  our 
own  endeavours.  But  when  this  method  of  convidlion  is  out 
of  our  power,  we  ought  to  weigh  the  degree  of  confidence 
which  the  defenders  of  the  oppofite  fa£ls  are  entitled  to  ;  to. 
examine  whether  analagous  fafts  do  not  lead  us  to  adopt  certatn 
refults ;  after  which  it  becomes  us  to  give  our  opinion  with  that 
modefty  and  circumfpedlion,  fuitablc  to  the  greater  or  lefs  de- 
gree of  probability  annexed  to  each  opinion. 

But  when  any  dpdrine  appears  to  us  to  be  eftabliflied  on  ex- 
periments of  fufficient  validity,  it  then  remains  to  be  tjpplied  to 
the  phetiomena  of  nature  and  art.  This.,  in  my  opinion,  is  the 
molt  certain  touchftone  to  diftinguifli  true  principles  from  thofe 
which  are  without  foundation.  And  when  I  obferve  that  all  the 
phenomena  of  nature  unite,  and  conform  themfelves,  as  it  were, 
to  any  theory,  I  conclude  that  this  theory  is  the  expreflion  and 
the  language  of  truth.     When,  for  example,  I  behold  that  % 


6B  Method  of  Studying 

plant  can  be  fupported  by  pure  water  alone,  that  metals  are  «^- 
clnable,  that  acids  are  formed  in  the  bowels  of  the  earth,  have  ^ 
I  not  a  right  to  conclude  that  the  water  is  decompofed  ?  and  do 
not  the  chemical  fa£ts  which  in  our  laboratories  afford  a  teftimo- 
ny  of  its  decompolition — do  not  thefe  acquire  a  new  force  by 
the  obfervation  of  the  preceding  phenomena  ?  I  conclude,  there- 
fore, that  we  ought  to  make  a  point  of  uniting  thefe  two  kinds 
of  proofs  :  and  a  principle  deduced  from  experiment  is  not,  in 
iny  opinion,  demonftrable,  until  I  fee  that  it  may  with  facility  be 
iipplied  to  the  phenomena  of  art  and  nature.     Hence,  if  I  find 
myfelf  in  a  ftate  of  hefitation  between  oppofite  fyftems,   I  will 
decide  in  favour  of  that  whofe  principles  and  experiments  adapt 
ihemfelves  naturally,  and  without  force  to  the  greateft  number 
of  phenomena.     I  will  always  diftruft  a  fmgle  fa61:,   which  is 
applicable  to  no  conclufion  ;  and  I  will  confider  it  as  falfc,  if  it 
be  in  oppofition  to  the  phenomena  which  nature  prefents  to  us. 
It  appears  to  me  likewife  that  he  who  profeifes  to  ftudy,  or 
even  to  teach  chcmiftry,  ought  not  to  endeavour  to  arrive  at  or  " 
exhibit  the  whole  which  has  been   done  in  each  department,  or 
to  follow  the  tedious  progrefs  of  the  human  mind  from  the  ori- 
gin of  a  difcovery  to  the  prefent  time.     This  faftidious  erudi- 
tion is  fatiguing  to  the  learner  •,  and  thefe  digreffions  ought  in 
no  cafe  to  be  admitted  in  the  enunciation  of  fcience,  excepting 
•when  the  hiftorical  details  afford   intereliing  facls,   or   lead    us 
by  uninterrupted  degrees  to  the  prefent  Hate  of  our  knowledge. 
It  rarely  happens,  however,  that  this  kind  of  refearches,  this  gen- 
ealogy of  fcience,  affords  us  fuch  characters  ;  and   it  ought  no 
more   to  be    admitted,    in  general,  that  an  elementary  writer 
ihould  bring  together  and  difcufs  every  thing  which  has  beeix 
<ione  in  a  fcience,  than  that  he  who  undertakes  to  diredl  a  trav- 
eller iliould  previouHy  enter  into  a  long  difTertation  on  all  the 
Toads  which  have  been  fuccefhvely   made,  and  on  thofe  which 
ilili  exift,  before  he  fhould  point  out  the  beft  and  fliorteft  way 
to  arrive  at  the  end  of  his  journey.     It  may,   perhaps,  be  faid 
of  the  hiftory  of  fcience,  and  more  efpecially  that  of  chemiftry, 
that  it  refembles  the  hiftories  of  nations.     It  fcldom  aflbrds  any 
light  refpeding  the  prefent  fituation  of  affairs ;  exhibits  many 
fables  concerning  pall  times  ;    induces  a  necefhty  of  entering 
into  difcuffions  upon  the  circumftances  that  pals  in  review  -,  and 
fuppofcs  a  mafs  of  extraneous    knowledge  acquired  on  the  part 
of  the  reader,  which  is  independent  of  the  purpofe  aimed  at  in 
the  ftudy  of  the  elements  of  chcmiftry. 

When  thefe  general  principles,  refpe61:ing  the  ftudy  of  chem- 
iftry, are  once  well  eftablilhed,  we  may  afterwards  proceed  in  the 
chemical  examination  of  bodies  in  two  ways  ;  we  may  either 


ihi  Science  of  Chemifiry.  6t> 

I  Ifcroceed  from  the  fimple  to  the  compound,  or  we  may  defcend  * 
^  -from  the  compound  to  the  fimple.  Both  thefe  methods  have 
their  inconvencies  ;  but  the  greateft,  no  doubt,  which  is  found 
in  following  the  firft  method  is,  that,  by  beginning  with  the  fim- 
pleft  bodies,  we  prefent  fubftances  to  the  confideration  of  the 
learner  which  nature  very  feldom  exhibits  in  fuch  a  flate  of  na- 
kednefs  and  fimplicity  j  and  we  are  forced  to  conceal  the  feries 
of  operations  which  have  been  employed  to  diveft  thefe  fubftan- 
ces from  their  combinations,  and  reduce  them  to  the  elementary* 
Itate.  On  the  other  hand,  if  we  prefent  bodies  to  the  view  of 
tbe  learner  fuch  as  they  are,  it  is  difficult  to  fucceed  in  an  accu- 
rate knowledge  of  them  ;  becaufe  their  mutual  action,  and  in 
general  moft  of  their  phenomena,  cannot  be  underftood  without 
the  previous  and  accurate  knowledge  of  their  conftituent  prin- 
ples,  iince  it  is  upon  thefe  alone  that  they  depend. 

After  having  maturely  confidered  the  advantages  and  incon- 
veniences of  each  method,  we  give  the  preference  to  the  iirft. 
We  ftiall  therefore  begin  by  giving  an  account  of  tlie  feveral  bod- 
ies in  their  moft  elementary  ftate,  or  reduce  to  that  term  beyond 
which  analyfis  can  effe£l  nothing  ;  and,  when  we  ihall  have 
explained  their  various  properties,  we  will  combine  thefe  bodies 
with  each  other,  which  will  afford  aclafsof  fimple  compounds: 
and  hence  we  (hall  rife  by  degrees  to  the  knowledge  of  bodies, 
and  the  moft  complicated  phenomena.  We  ftiall  be  careful,  in 
any  examination  of  the  feveral  bodies  to  which  we  fliall  d:re6^ 
our  refearches,  to  proceed  from  known  to  unknown  ;  and  our 
iirll  attention  (hall  be  directed  to  the  elementary,  fubftances. 
But  as  it  is  impoflible,  at  one  and  the  fame  time,  to  treat  of 
all  thofe  fubftances,  which  the  prefent  ftate  of  our  knowledge 
obliges  us  to  confider  as  elementary,  we  ftiall  confine  ourfelves 
to  the  exhibition  of  fuch  as  are  of  the  greateft  importance  in  the 
phenomena  of  the  globe  we  inhabit,  fuch  as  are  almoft  univer- 
lally  fpread  over  its  furface,  and  fuch  as  enter  as  principles 
into  the  compofition  of  the  re-agents  moft  frequently  employed 
in  our  operations  j  fuch,  in  a  word,  as  we  continually  find  in 
the  examination  and  analyfis  of  the  component  parts  of  the  globe. 
Light,  heat,  fulphur,  and  carbone  are  of  this  number.  Light 
modifies  all  our  operations,  and  moft  powerfully  contributes  to 
the  production  of  all  the  phenomena  which  appertain  to  bodies 
either  living  or  inanimate.  Heat,  diftributed  after  an  unequal 
proportion  r.mong  all  the  bodies  of  this  univerfe,  eftablilhes  their 
various  degrees  of  confiftence  and  fixity  ;  and  is  one  of  the 
great  means  v/hich  art  and  nature  employ  to  divide  and  vola- 
tilize bodies,  to  weakeai  their  force  or  adhefion,  and  by  that 
means  prepare  them  for  analyfis.     Sulphur  exifts  i^  the  products 


^Q  pimple  or  Elementary  SubJIances, 

of  the  three  kingdoms  ;  it  forms  the  radical  of  one  of  the  lfll|fl 
J^nown,  and  moft  generally  employed,  acids ;  it  exhibits  inter-^^* 
efting  combinations  with  moft  fmiple  fubftances  5  and  under 
there  feveral  points  of  view,  it  is  one  of  the  fubftances  the  moft 
neceifary  to  be  known  in  the  firit  fteps  of  chemical  fcience. 
The  fame  may  be  faid  of  carbone  -,  it  is  the  moft  abundant  fixed 
product  found  in  vegetables  and  animals.  Analyfls  has  difcuv- 
€red  it  in  fome  mineral  fubftances.  Its  combination  with  oxi- 
geiie  is  fo  common  in  bodies,  arid  in  the  operations  of  art  and 
nature,  that  there  are  fcarcely  any  phenomena  which  do  not  pre- 
fent  it  to  our  view,  and  which  confequehtly  require  the  knowl- 
edge of  its  properties.  From  all  thefe  reafons  it  appears  to  us, 
that  for  the  advancement  of  chemiftry  it  is  neceflary  our  firft 
proceeding  fhouid  be  founded  on  the  knowledge  of  thefe  fub- 
ftances J  and  that  we  fliould  riot  direct  our  attention  to  other 
fimple  or  elementary  fubftances,  accordingly  as  they  prefcii^^ 
themfelves. 


SECTION   IV, 
Concerning  Simple  or  Elementary  Subllances, 


I 


F  we  caft  ^n  eye  over  the  fyftems  which  have  htu\ 
fuccefFively  formed  by  philofophers  relative  to  the  number  and 
nature  of  the  elements,  we  fliall  be  aftonifhed  at  the  prodigious, 
variety  which  prevails  m  their  manner  of  thinking.  In  the 
earlieil  times,  every  one  feems  to  have  taken  his  own  imagina- 
tion for  his  guide  •,  and  we  find  no  reafonable  fyftem  until  the 
time  when  Ariftotle  and  Empedocles  acknowledged  as  elements. 
Air,  Water,  Earth,  and  Fire.  Tlveir  opinion  has  been  well  re- 
ceived for  many  ages  ;  and  it  must  be  confefied  that  it  is  calcu- 
lated to  feduce  the  mind.  There  are,  in  facl,  enormous  maiT- 
es,  and  inexhauftible  ftores,  that  prefent  themfelves  to  cur  view 
of  thefe  four  principles,  to  which  the  deftrudion  or  decompo- 
fition  of  bodies  appeared  to  refer  all  the  feveral  component  parts 
which  formation  or  creation  had  taken  from  them.  The  author- 
iry  of  all  thofe  great  men  who  had  adopted  this  fyftem,  and  th^ 
analyfis  of  bodies  which  prefented  only  thele  four  principles,, 
aflorded  fuiBcient  grounds  for  admitting  this  dodrine. 


■■L  Fire,  or  Heai,  'j  I 

iut  as  foon  as  clieiiiiflry  had  advanced  fo  far  as  to  difcovcr 
principles  of  bodies,  the  profelTors  of  that  fcience  prefumed 
to  mark  the  number,  nature,  and  charafter  of  the  elements  ; 
ar^d  every  fubftance  thit  was  unalterable  by  the  chemical  meth- 
ods of  decompofition,  was  confidered  by  them  as  a  limplc  or 
elementary  principle.  By  thiis  taking  the  limits  of  anaiyfis  as 
the  term  for  indicating  the  elements,  the  number  and  the  nature 
of  thefe  mud  vary  according  td  the  revolutions  and  the  progrefs 
of  chemiftry.  This  has  accordingly  happened,  as  may  be  feen 
by  confuiting  all  the  authors  who  have  written  on  this  fiibje61:, 
from  the  time  of  Paracelfus  to  the  prefent  day.  But  it  muit  be 
confeiTed  that  it  is  no  fmall  degree  of  rafhnefs,  to  affume  the 
€xten^  of  the  povver  of  the  artift  as  a  limit  for  that  of  the  Creator, 
and  to  imagine  that  the  ftate  of  our  acquifitipns  is  a  ftate  of  per-* 
feet  knowledge. 

The  denomination  of  Elements  ought  therefore  to  be  effaced 
from  a  chemic^^l  nomenclature,  or  at  leaft  it  ought  not  to  be  u- 
fed  but  as  an  exprelilon  denoting  the  lad  term  of  our  analytical; 
te(u(ts  ;  and  it  is  always  in  this  fenfe  that  we  (hall  ufc  the 
^^rd. 

CHAPTER  i. 

iCtnc^rning  Fire.. 

THE  principal  agent  employed  by  nature  to  balance  the  pow- 
er and  natural  effe£t  of  attracftion,  is  fire.  By  the  natural  effedlt 
of  attraiflion  we  (hould  poflcfs  none  but  folid  and  compact  bod- 
ies 5  but  the  calorick  unequally  difperfed  in  bodies  tends  incef- 
fantly  to  deftroy  this  adhefion  of  the  particles ;  and  it  is  to  this 
principle  that  we  are  indebted  for  the  varieties  of  confiftence  un- 
der which  bodies  prefent  themfelves  to  our  obferyatlon.  The 
various  fubftances  that  compofe  this  univerfe  are  therefore  fiib- 
jetted,  on  the  one  hand,  to  a  general  law  which  tends  to  bring 
them  together  •,  and,  on  the  other  hand,  to  a  powerful  agent 
which  tends  to  remove  them  from  each  other  :  it  is  upon  ihd 
refpe£tive  energy  of  thefe  two  forces  that  the  confiftence  of  all 
bodies  depends.  Whch  the  affinity  prevails,  they  are  in  the 
folid  (late  ;  when  the  calorick  is  riioft  powerful,  they  are  in  the 
ftate  of  gas  *,  and  the  liquid  ftate  appears  to  be  the  point  of  the 
equilibrium  between  thele  two  powers. 

It  is  tlicrefore  eflentially  necelmry  to  treat  of  fire,  (ince  it  a<ft5 
fo  leading  a  part  in  this  univerfe  j  and  becaufe  it  is  impofTible 
to  treat  of  any  fubftance  whatever,  without  attending  to  the  in- 
fluence of  this  agent. 


72  J^re.     Heat,     Light. 

There  are  two  things  to  be  confidered  in  lire — heat  and  Hghi!!^ 

Thefe  two  principles,  which  have  been  very  often  confound- 
ed, appear  to  be  very  diftinft  in  their  own  nature  ;  becaufe  they 
are  Tcarcely  ever  proportional  to  each  other,  and  becaufe  each 
can  exift  without  the  other. 

The  mod  ufual  acceptation  of  the  word  Fire  comprehends 
heat  and  light  -,  and  its  principal  phenomena  mull:  have  been 
known  for  a  long  time.  The  difcovery  of  fire  mud  have  been 
nearly  as  ancient  as  the  human  fpecies  upon  this  globe.  The 
iliock  of  two  flints,  the  a6lion  of  meteors,  or  the  efFe<fl:  of  volca- 
noes, mull  have  afforded  the  earliell:  idea  of  it  ;  and  it  is  very 
iiftonifning  that  the  inhabitants  of  the  Marian  Illands  were  not 
acquainted  with  its  efFcdls  before  the  invafion  of  the  Spaniards. 
Thefe  iflanders,  who  became  acquainted  with  this  terrible  ele- 
ment only  in  confequence  of  its  ravages,  confidered  it  at  firfl  as  a 
malevolent  being  which  attached  itfelf  to  all  beings,  and  devour- 
ed them. — See  the  Abbe  RaynaPs  Hiflioire  Philofophique,  &c. 

The  efFe<n:s  of  fire  are  perhaps  the  molt  aftonifhing  of  any 
which  nature  exhibits  *,  and  we  ought  not  to  be  furprized  that 
the  ancients  confidered  it  as  an  intermediate  being  between 
fpirit  and  matter,  and  have  built  the  beautiful  fable  of  Prome- 
theus upon  its  origin.  We  have  had  the  happinefs,  in  our 
time,  to  acquire  well-founded  and  extenfive  ideas  refpe£ling 
this  agent,  which  we  (hall  proceed  to  develope  in  the  two  fol- 
lowing articles. 

ARTICLE  I. 

Concerning  Calorick  and  Heat. 

When  a  metal  or  a  liquid  Is  heated,  thefe  bodies  are  dilated 
in  every  direction,  are  reduced  to  vapour,  and  at  lad  become 
invifible  when  the  mod  powerful  heat  is  applied  to  them. 

Bodies  which  poflefs  the  principle  of  heat,  part  with  it  more 
or  lefs  readily.  If  we  attentively  obferve  a  body  during  its 
cooling,  a  flight  movement  of  undulation  will  be  perceived  in 
the  furrounding  air  ;  an  efFecl  which  may  be  compared  to  the 
phenomenon  exhibited  upon  the  mixture  (if  two  liquors  of  une- 
qual denfity  and  weight. 

It  is  difllcult  to  conceive  this  phenomenon  without  admitting 
of  a  peculiar  fluid,  which  pafles  fird  from  the  body  which  heats 
to  that  which  is  heated,  combines  with  the  latter,  produces  the 
efivcls  we  have  fpoken  of,  and  afterwards  efcapes  to  unite  with 
othe-  bodies,  according  to  its  aflinities,  and  the.  law  of  equilib- 
rium, to  which  all  bodies  tend. 


w. 


u 


General  Properties  of  Heat,  73 


This  fluid  of  heat,  which  we  call  Calorick,  is  contained  in 
greater  or  lefs  quantities  in  bodies,  according  to  the  greater  or 
lefs  degrees  of  affinity  exifting  between  it  and  them. 

Various  means  may  be  employed  to  difplace  or  difengage  the 
calorick.  The  firft  is  by  the  method  of  affinities  :  for  example, 
water  poured  upon  the  fulphurick  acid  expels  the  heat,  and 
takes  its  place  ;  and  while  there  is  a  difengagement  of  heat,  the 
volume  of  the  mixture  does  not  increafe  in  proportion  to  the 
bulk  of  the  two  fubftances  mixed.  This  (hews  that  penetration 
takes  place,  which  cannot  be  explained  but  by  admitting  that 
the  integrant  parts  of  the  water  take  the  place  of  the  calorick, 
in  proportion  as  it  is  diflipated. — ^The  fecond  method  of  precip- 
itating calorick,  is  by  fri&ion  and  compreffion.  In  this  cafe  it 
is  exprefTed  or  fqueezed  out,  in  the  fame  manner  as  water  from 
a  fpunge.  In  reality,  the  whole  of  the  heat  which  may  be  pro- 
duced by  fridlion,  is  not  afforded  by  the  body  itfeif  i  becaufe, 
in  proportion  as  the  interiour  heat  is  developed,  the  external  air 
afts  upon  the  body,  calcines  or  inflames  it,  and  itfeif  gives  out 
heat  during  its  fixation.  Fermentation,  and  in  general  every 
operation  which  changes  the  nature  of  bodies,  may  difengage 
calorick,  becaufe  the  new  compound  ni%  demand  and  receive 
a  greater  or  lefs  quantity.  Hence  it  is  that  chemical  operations 
produce  fometimes  cold,  and  fometimes  heat. 

Let  us  now  examine  the  form  under  which  calorick  prefenta 
itfeif. 

This  fluid  is  difengaged  either  in  a  ftate  of  liberty,  or  in  a  ftaft: 
of  combination. 

In  the  firfh  cafe,  the  calorick  always  endeavours  to  obtain  an. 
equilibrium  ;  not  that  it  is  diftributed  equally  among  all  bodies, 
but  it  is  difperfed  among  them  according  to  the  degrees  of  it« 
afllinity.  Whence  it  follows,  that  the  circumambient  bodies  re- 
ceive and  retain  a  quantity  more  or  lefs  confiderable.  Metals 
are  eafily  penetrated  by  this  fluid,  and  tranfmit  it  with  equal 
facility  ;  wood  and  animal  fubftances  receive  it  to  the  degree 
of  combuftion  j  liquids,  until  they  are  reduced  to  vapour.  Ice 
alone  abforbs  all  the  heat  communicated  to  it,  without  giving 
it  out  to  other  bodies  until  it  has  acquired  the  fluid  ftate*. 

The  degree  of  heat  can  be  appreciated  only  by  its  effects  :  and 
the  inftruments  which  have  been  fucceffively  invented  to  calcu- 
late it,  and  are  known  by  the  name  of  thermometers,  pyrome- 
ters, &c.   have  been  applied  to  the  ftrid:  determination  of  the 

*  The  ingenious  author  has  inadrertenily  been  guilty  of  an  fcverfighr- 
Not  only  ice,  but  all  other  bodicB,  abforb  he;^t,  during  litjucfi^iXn,  as  h« 
himfclf  fliews  hereafter.      T, 

K 


74  Admeafurement  of  Heat, 

feveral   phenomena   exhibited  in  confequence  of  the  abforptloii 
of  calorick  in  various  bodies. 

The  dilatation  of  fluids  or  of  metals  in  the  fluid  ftate,  by  the 
feveral  degrees  of  heat,  has  been  long  meafured  by  thermome- 
ters formed  of  glafs  ;  but  this  very  fufible  fubflance  can  only 
be  ufed  to  afcertain  degrees  of  heat  inferiour  to  that  which  ren- 
ders the  glafs  itfelf  fluid. 

Several  means  have  been  fuccefllvely  propofed  for  calculating 
the  higher  degrees  of  heat.  Mr.  Leidenfroft  has  proved  that 
the  hotter  a  metal  is,  the  more  Ilowly  will  drops  of  water  evap- 
orate from  its  furface  -,  and  he  has  propofed  this  principle  for 
the  conftrudion  of  pyrometers.  A  drop  of  water  in  an  iron 
fpoon,  heated  to  the  degree  of  boiling  water,  evaporates  in  ons 
fecond  ;  a  fimilar  drop,  poured  on  melted  lead,  is  diflTi'pated  in 
fix  or  feven  feconds  ;  and  upon  red  hot  iron  in  thirty.  Mr. 
Ziegler,  in  his  Specimen  de  digefl:ore  Papini,  has  found  that  89 
feconds  were  required  to  evaporate  a  drop  of  water  at  5  20  degrees' 
of  Fahrenheit ;  and  that  one  fecond  is  fufficient  at  the  300th  de- 
gree. This  phenomenon,  which  is  more  interefting  to  chemidy 
than  pyrometry,  to  which  it  will  always  affbrd  refults  little  fuf- 
ceptible  of  rigorous  Cc^ulation,  appears  to  me  to  depend  upon 
the  adhefion  and  decompofition  of  the  water  upon  the  metal. 

The  moft  accurate  pyrometer  we  are  acquainted  with,  is  that 
which  was  prefented  to  the  Royal  Society  of  I^ondon  by  Mr. 
Wedgwood.  It  is  conilrudled  upon  the  principle,  that  the 
purelt  clay  fhrinlcs  in  the  fire  in  proportion  to  the  heat  applied 
to  it.  This  pyrometer  confifts  of  two  parts  \  one  called  the 
gauge,  which  ferves  to  meafure  the  degrees  of  diminution  or 
fiirinking  ;  the  other  contains  the  fimple  pieces  of  pure  clay, 
which  are  called  thermometer  pieces^ 

The  gauge  is  formed  of  a  plate  of  baked  earth,  upon  which 
are  applied  tv/o  rulers  or  (Iraight  pieces  of  the  fame  fubftance. 
Thefe  rulers,  being  perfectly  {traight  and  even,  are  placed  at  the 
diftance  of  half  an  inch  from  each  other  at  one  of  their  ends, 
and  three  tenths  of  an  inch  at  the  other.  For  greater  conven- 
ience the  gauge  is  divided  into  two  parts,  and  the  two  pieces  are 
placed  endways  when  required  to  be  ufed.  The  length  of  this 
rule  is  divided  into  240  equal  parts,of  which  each  reprefents  one 
tenth  of  an  inch.*  To  form  the  thermometer  pieces,  the  earth 
is  fifted  with  the  greatell  attention,  after  which  it  is  mixed  with 
water,  and  the  palte  thrufl  through  an  iron  tube,  which  gives  it 
a  cylindrical  fori^i,  to  be  cut  afterwards  into  pieces  of  a  proper 

♦This  is  in  facfl,  the  twelve-hundredth  of  an  iacU  ia  ths  width  riccording  to 
the  dimenfioas  here  given.  T. 


WedgwoocPs  Thermometer^  75^ 

fize,  When  the  pieces  are  dry,  they  muft  be  prefentecl  to  the 
gatige,  where  they  ought  to  fit  at  the  place  of  o  on  the  fc^le. 
It  by  inadvertence  of  the  workmen  any  piece  penetrates  to  oiks 
Lr  two  degrees  further,  this  degree  is  marked  on  its  flat  furface, 
.and  requires  to  be  dedudled  when  the  piece  is  ufed  in  the  ad- 
jneafurement  of  heat.  The  pieces  thus  adjulted  are  baked  in  a 
furnace  to  a  red  heat,  to  give  them  the  confiflence  ncceflary  for 
t'arriage.  The  heat  employed  in  this  part  of  the  procefs  is  ufu- 
ally  about  fix  degrees,  and  the  pieces  are  diminiflied  more  or 
lefs  •,  but  this  is  of  no  confequence  when  they  come  to  be  fub- 
mitted  to  a  fuperiour  degree  of  heat  ;  and  if  it  fiiould  happen 
that  an  inferiour  degree  of  heat  is  required  to  be  meafured,  un- 
baked pieces  arq  to  be  ufed,  which  are  preferved  in  flieaths  or 
cafes  to  avoid  friiflion. 

When  this  pyrometer  is  to  be  ufed,  one  of  the  pieces  is  ex- 
pofed  in  the  fire-place  whofe  heat  is  required  to  be  deteririn- 
ed  ;  and  when  it  has  acquired  the  whole  intenfiiy,  it  is  taken 
out,  and  fuflered  to  cool,  or  for  greater  fpeed  it  is  plunged  in 
water  •,  after  which  it  is  prefented  to  the  gauge,  and  its  degree 
of  contraQion  eafily  determined.  Mr.  Wedgwood  has  given 
us  the  refult  of  feveral  experiments  made  with  his  pyrometer, 
oppofite  to  which  he  has  placed  the  corjrefpondent  degrees  of 
Fahrenheit. 

Red  heat  vilible  by  the  light 

Brafs  melts  at 

Swedilh  copper  melts  at 

Pure  liiver  melts  at 

Pure  gold  melts  at 

The  heat  of  bars  of  iron  raifed  to  )  fmall  bar 

welding  _       ^       \  large  bar 

The  greateft  heat  producible  in  a  fmith's  forge 
Call  iron  melts  at 
The  greateft  heat  of  a  wind  furnace  of  eight  J 

inches  fquare  i 

Thefe  various  thermometers  are  not  applicable  to  all  cafes. 
We  cannot,  for  example,  calculate  with  flridlnefs  the  heat 
which  efcapes  from  living  bodies,  or  determine  with  precifion 
the  temperature  of  any  fubitance.  But  Meflrs.  De  la  Place 
and  Lavoifier  (Acad,  des  Sciences,  1780)  have  invented  an  ap- 
paratus which  appears  to  leave  nothing  further  to  be  defired. 
It  is  conflrucled  upon  the  principle  that  ice  abforbs  all  the  heat 
communicated  to  it,  without  communicating  it  to  other  bodies 
until  the  M'hple  is  melted  ;  fo  tnat  from  hence  we  may  calculate 
the  degrees  of  heat  communicated,  by  the  quantity  of  ice  which 
is  melted.  It  was  necefTary,  in  order  to  atFord  flrict  refults,  to 
4ifcover  the^ieans  of  caufing  the  ice  to  abforb  all  the  heat  dif- 


Pyrometer 

Thermometer 

of  VVtUgwood* 

uf  Fahrenheit. 

0 

1077 

ai 

1857 

37 

4587 

a8 

4717 

3* 

5»57 

90 

127',7 

95 

13427 

1^5 

17327 

130 

17977 

160 

21877 

'j6  The  Calorimeter  of 

engaged  from  the  bodies  under  examination,  and  to  cover  it 
from  the  aiflion  of  every  other  fubftance  M^hich  might  facilitate 
its  fufion  y  and,  laftly,  to  collet  with  great  care  the  water  pro- 
duced by  the  fufion. 

The  apparatus  conftru£led  by  thefe  two  celebrated  academi- 
cians for  this  purpofe,  confifts  of  three  circular  veffels  nearly  in-* 
fcribed  in  each  other  ;  fo  that  three  capacities  are  produced. 
The  interiour  fpace  or  capacity  is  formed  by  an  iron  grating, 
upon  fupports  of  the  fame  metal.  Here  it  is  that  the  bodies 
fubje6led  to  experiment  are  placed.  The  upper  part  of  this 
cavity  is  clofed  by  means  of  a  cover.  The  middle  fpace,  next 
to  this,  is  defigned  to  contain  the  ice  which  furrounds  the  inte- 
riour compartment.  This  ice  is  fupported  and  retained  by  a 
grate,  upon  which  a  cloth  is  fpread.  In  proportion  as  the  ice 
melts,  the  water  flows  through  the  grate  and  cloth,  and  is  col- 
lected in  a  veffel  placed  beneath.  Laftly,  the  external  fpace  or 
compartment  of  the  apparatus  contains  ice  intended  to  prevent 
the  effedl  of  the  external  heat  of  the  atmofphere. 

To  ufe  this  excellent  machine,  the  middle  or  fecond  fpace  is 
filled  with  pounded  ice,  as  is  likewife  the  cover  of  the  internal 
fphere ;  the  fame  thing  is  done  with  regard  to  the  external  fpaccj 
as.  well  as  to  the  general  covering  of  the  whole  machine  :  the 
interiour  ice  is  fuffered  to  drain  ;  and,  when  it  ceafes  to  afford 
water  the  covering  of  the  internal  fpace  is  raifed,  to  introduce 
the  body  upon  which  the  experiment  is  intended  to  be  made. 
Immediately  after  this  introduction,  the  covering  is  put  on,  and 
the  whole  apparatus  remains  untouched  until  the  included  body 
has  acquired  the  temperature  of  o>  or  the  freezing  temperature 
of  water  j  which  is  the  common  temperature  of  the  internal  ca- 
pacity. The  quantity  of  water  afforded  by  the  melting  of  the 
ice  is  then  weighed  ;  ard  this  is  an  accurate  meafure  of  the 
heat  difengaged  from  the  body,  becaufe  the  fufion  of  the  ice  is 
the  effcCl;  of  this  heat  only.  Experiments  of  this  kind  lall 
fifteen,  eighteen,  or  twenty  hours. 

Ic  is  of  great  confequence,  that  in  this  machine  there  fhould 
be  no  communication  between  the  middle,  or  fecopd,  and  the. 
external  fpace. 

It  is  likewife  neceffary  that  the  air  of  the  apartment  fhould  not 
he  lower  than  o,  becaufe  the  interiour  ice  would  then  receive  a 
degree  of  cold  lower  than  that  temperature. 

Specifick  heat  is  merely  the  proportional  quantity  of  heat 
neceffary  to  raife  bodies  of  eqiW  mafs  to  the  fame  number  of 
degrees  of  temperature  ;  fo  that,  when  the  fpccifick  heat  of  a 
folid  body  is  required,  its  temperature  muft  be  elevated  a  cer- 
tain number  of  degrees,  at  which  inftant  it  muft  be  placed  in 


Lavoifter  and  Be  la  Place,  ^fj 

the  internal  fphere,  and  there  left  until  its  temperature  Is  reduc- 
ed to  o.  The  water  is  then  collected,  and  this  quantity  divided 
by  the  produ£l  of  the  mafs  of  the  body  ;  and  the  number  of 
degrees  of  its  original  temperature  above  o,  will  be  proportional 
to  its  fpecifick  heat. 

With  regard  to  fluids,  they  are  inclofed  in  veflels  whofe  heat 
has  been  previoufly  determined.  The  operation  is  then  the  fame 
as  for  folids  :  excepting  that  the  quantity  of  water  afforded  must 
be  diminished  by  a  dedudion  of  that  quantity  which  has  been 
melted  by  the  heat  of  the  vefTel. 

If  it  be  required  to  determine  the  heat  which  is  difengaged 
during  the  combination  of  various  fubftances,  they  mufl  be  all 
reduced,  as  well  as  their  containing  velTels,  to  the  temperature  of 
o.  The  mixture  mufl  then  be  placed  in  the  internal  fphere  ; 
and  the  quantity  of  water  collected  is  the  meafure  of  the  difen- 
gaged heat. 

In  order  to  determine  the  heat  of  combuftion  and  refpiration, 
as  the  renewal  of  air  is  indiipenfable  in  thefe  two  operations,  it  is 
necefTary  to  eftabllfh  a  communication  between  the  internal  part 
of  the  fphere  and  the  furrounding  atmofphere  ;  and  in  order  that 
the  introdudlion  of  frefh  air  may  not  caufe  any  perceptible  errour, 
thefe  experiments  ought  to  be  made  at  a  temperature  little  differ- 
ing from  o,  or  at  lealt  the  air  which  is  introduced  muft  previ- 
oufly be  brought  to  this  temperature. 

To  determine  the  fpecifick  heat  of  any  gas,  it  is  necefiary  to 
eftablifli  a  current  through  the  internal  part  of  the  fphere,  and 
to  place  two  thermometers,  one  at  the  place  of  introdudion, 
and  the  other  at  the  place  of  efcape.  By  comparifon  of  the 
temperatures  exhibited  by  thefe  two  inflruments,  a  judgment: 
is  formed  of  the  heat  abforbed,  and  the  melted  ice  is  meafured. 

An  excellent  memoir  of  Meffrs.  De  la  Place  and  Lavoifier 
may  be  confulted  for  the  refults  of  the  experiments  they  have 
made.  The  prefent  extradt  contains  only  a  fliort  account  of 
their  valuable  labours. 

The  various  means  made  ufc  of  for  the  admeafurement  of 
heat,  are  founded  on  the  general  principle,  that  different  bodiss 
abforb  heat  in  greater  or  lefs  quantities.  If  this  fa<£l  were  not 
generally  admitted,  it  might  be  eftabliftied  on  the  three  follow- 
ing fa61s.  Dr.  Franklin  having  expofed  two  fmall  pieces  of 
cloth,  of  the  fame  texture  but  of  difl'erent  colours,  upon  the  fur- 
face  of  fnow,  perceived,  a  few  hours  afterwards,  that  the  red 
cloth  was  buri(  d  in  the  fnow,  while  the  other  which  was  white 
Jliad  not  fuffered  any  deprefhon.*     M.  de  SaufTure  obferves.  that 

*  They  were  cxpofcd  t©  the  rays  of  the  fun.    T, 


7'^  General  Properties  of  Heat , 

t\it  peafants  of  the  mountains  of  Switzerland  are  careful  t<> 
fpread  a  black  earth  over  the  furface  of  grounds  covered  with 
fnow,  uhen  they  are  defirous  of  mehing  it,  to  fow  their  feed. 
So  likewife  children  burn  a  black  hat  in  the  focus  of  a  fmalllens 
which  would  fcarcely  heat  a  white  one. 

Such  nearly  are  the  phenomena  of  heat  when  it  is  difengaged 
in  a  (late  of  liberty.  Let  us  now  contemplate  thofe  which  it 
prefents  when  it  efcapes  from  a  Itate  of  combination. 

Heat  is  fometimes  difengaged  in  a  ftate  of  fimple  mixture,  as 
in  the  phenomena  of  vapours,  fublimations,  &c.  If  heat  be 
applied  to  water,  thefe  two  fluids  will  unite,  and  the  mixture, 
will  be  diilipated  in  the  atmofphere  ;  but  it  would  be  an  abiffe 
of  words  to  call  fo  weak  an  union  by  the  name  of  combinatijon  : 
for,  as  foon  as  the  heat  becomes  in  a  fituation  to  combhie  with 
other  bodies,  it  abandons  the  water,  which  returns  to  a  liquid 
ftate.  This  body,  during  evaporation,  continually  carries  with 
it  a  portion  of  heat  ;  and  hence,  perhaps,  refult  the  advantages 
©f  tranfpiration,  perfpiration,  &c. 

But  heat  very  frequently  contrafts  a  true  chemical  union  with 
the  bodies  which  it  volatilizes :  this  combination  is  even  fo  per- 
feft,  that  the  heat  is  not  perceptible,  but  is  neutralized  by  the 
body  with  which  it  is  combined.  It  is  then  called  latent  heat, 
e-alor  latens. 

The  feveral  cafes  in  which  heat  enters  into  combination,  and 
pafles  to  the  ftate  of  latent  heat,  may  be  reduced  to  the  two  foU 
lowing  principles : 

The  firft  principle. — Every  body  vi^hich  paifes  from  the  foKd 
to  the  liquid  ftate,  abforbs  a  portion  of  heat,  which  is  no  longer 
fenfible  to  the  thermometer,  but  exiils  in  a  true  ftate  of  combi- 
nation. 

The  academicians  of  Florence  filled  a  veflel  with  pounded  ice, 
and  plunged  a  thermometer  in  it,  which  defcended  to  o.  The 
\efil'l  was  ihenimmerfed  in  boiling  water,  and  the  thermome- 
ter did  not  rife  during  the  whole  time  of  the  li-quefadlion  of  the 
ice.     The  fufion  of  ice  therefore  abforbs  heat. 

Mr.  Wilcke  poured  a  pound  of  water,  heated  to  the  6oth  de- 
gree of  Reaumur,  upon  a  pound  of  ice.  The  melted  mixture 
poflefied  the  temperature  of  o.  Sixty  degrees  of  h:at  had  there- 
fore .entered  into  combination. 

The  Chevalier  Laudriani  has  ftiewn  that  the  fufion  of  metals, 
of  fulphur,  of  phofphorus,   of  alum,   of  nitre,  &c.  abforb  heat. 

Cold  is  produced  in  the  diflblution  of  all  the  cryftaliized  falts> 

Reaumur  made  a  feries  of  very  intereRing  experiments  on 
this  fubje£l,  which  confirm  thofe  of  Boyle.  Fahrenheit  caufed 
the  thciiiicirxter  to  dcfcend  to  forty  degrees,  by  meltiug  ice  by 


General  Properiles  of  Heat,  79 

ftrong  nitrous  acid.  But  the  mofl:  aftonifliing  experiments  are 
thofe  made  by  Meffrs.  Thomas  Beddces,*phyfician,  and  Walker, 
apothecary  at  Oxford,  and  inferted  in  the  Philofophical  Tran^ 
actions  for  the  year  1787.!  The  mixtures  which  produced  the 
greatell  degrees  of  cold  are,  i.  Eleven  parts  of  muriate  of  am- 
moniack,  or  common  fal  ammoniack  ;  ten  parts  of  nitrate  of 
pot-afli,  or  common  nitre  ;  fixteen  parts  of  fulphatc  of  foda,  or 
Glauber's  fait  ;  with  thirty-two  parts  by  weight  of  water  :  the 
two  fir  ft  falts  fliould  be  dry,  and  in  powder.  2.  The  nitrick 
acid,  muriate  of  ammoniack,  and  fulphate  of  foda,  lowered  the 
thermometer  to  eight  degrees  under  o.  Mr.  Walker  has  frozen 
mercury  without  ufing  either  ice  or  fnow. 

It  is  therefore  an  incontrovertible  principle,  that  all  bodies 
which  pafs  from  the  folid  to  the  liquid  Itate,  abforb  heat,  and 
retain  it  in  fo  accurate  a  combination  as  to  afford  no  fign  of  it3 
prefence.     The  heat  is  therefore  fixed,  neutralized  or  latent. 

The  fecond  principle. — Ail  bodies,  by  palTing  from  the  folid 
or  fluid  (late  to  the  aeriform  ftatc,  abforb  heat,  which  becomes 
latent  ;  and  it  is  by  virtue  of  this  heat  that  fuch  bodies  areplac- 
.ed  and  maintained  in  that  ftate.  \ 

On  this  principle  is  founded  the  proCefs  ufed  In  China,  India> 
Perfia,  and  Egypt,  to  cool  liquors  ufed  for  drink. 

The  water  intended  for  this  purpofe  is  put  into  very  porous 
vefiels,  and  expofed  to  the  fun,  or  to  a  current  of  warm  air,  to 
cool  the  fluid  contained  v/ithin  them. 

It  is  by  fimilar  means  that  cool  drink  is  obtained  in  the  long 
journies  of  the  caravans.  Interefling  details  on  this  fubjedt 
may  be  feen  in  the  Travels  of  Chardin,  vol.  iri.  1723  ;  Taver- 
nier's  Voyages,  vol.  i.  edit.  1738  ;  Paul  Lucas's  Voyages,  vol.  ii. 
edit.  1724  *,  and  allb  in  the  Mundus  Subterraneous  of  P.  Kir- 
elier,  lib.  vi.  fee  2.  cap.  2. 

W^e  may  conclude  from  the  experiments  of  Mr.  Richmann, 
made  in  1747,  and  inferted  in  the  firft  volume  of  the  imperial 
Academy  of  Peterfburgh,  i.  That  a  thermometer  taken  out  of 
water,  and  cxr  ofed  to  the  air,  always  dcfcends,  even  when  its 
temperature  is  equal  or  fuperiour  to  that  of  the  water.  2.  That 
it  afterwards  rifes,  until  that  it  has  acquired  the  temperature  of 
the  atmofphere.  3.  That  the  time  of  defcending  is  lefs  than  that 
which  it  employs  to  rife  again.     4.  That  when  the  thermometer, 

*  It  docs  not  appear  that  Dr.  Eeddocs  either  had  or  prttcnds  to  have  any 
other  fliart-  in  the  experiments  of  Mr.  VVHlker  than  that  of  having  tr4nihiiuc4 
tliem  to  the  Royal  Society. 

t  Alfo  in  the  fubfcquent  vglumcs, 


S(5  General  Properties   of  Heat* 

"Withdrawn  from  the  water,  has  arlfen  to  the  common  tempera- 
ture, its  bulb  is  dry  ;  but  that  it  continues  wet  during  the  whole 
time  of  its  Handing  beneath  this  common  temperature. 

To  thefe  confequences  we  fhall  add  others  deduced  from  fev- 
eral  curious  experiments  by  the  celebrated  Cullcn.  i.  A  ther- 
mometer fufpended  in  the  receiver  of  the  air  pump,  defcends 
two  or  three  degrees  during  the  time  of  exhauftion,  and  after- 
wards rifes  to  the  temperature  of  the  vacuum.  2.  A  thermom- 
eter plunged  in  alcohol,  in  the  receiver  of  the  air  pump,  always 
defcends,  and  the  lower  in  proportion  as  the  bubbles  are  ftrong- 
er  which  ilTue  from  the  alcohol  ;  if  it  be  withdrawn  from  this 
liquor,  and  fufpended  wet  beneath  the  receiver,  it  falls  eight  or 
ten  degrees  while  the  air  is  pumping  out. 

Ic  is  well  known  that  if  the  ball  of  a  thermometer  be  wrap- 
ped in  fine  linen,  and  kept  moid  by  fprinkling  with  ether,  and 
the  evaporation  be  facilitated  by  agitation  in  the  air,  the  the- 
mometer  will  defccnd  to  o. 

The  immortal  Franklin  has  proved,  in  his  own  perfon,  that 
when  the  body  perfpires  ftrongly,  it  is  lefs  heated  than  furround- 
ing  bodies,  and  that  perfpiration  always  produces  a  certain  de- 
gree of  coldnefs. — See  his  letter  to  Dr.  Lind. 

The  great  number  of  labourers  in  the  burning  heat  of  our 
climate  fupport  themfelves  only  by  virtue  of  a  copious  perfpira- 
tion, the  fluid  for  which  they  replenifh  by  drinking  plentifully. 
The  workmen  employed  in  glafs-houses,  founderies,  &c.  often 
live  in  a  medium  hotter  than  their  bodies,  the  natural  tempera- 
ture of  which  is  equalized  and  moderated  by  perfpiration. 

If  evaporation  be  increafed  by  agitation  of  the  air,  the  refrig- 
eration is  the  greater.  Hence  the  ufe  of  fans,  ventilators,  &c. 
which,  though  intended  to  give  motion  to  warm  air,  afford  like- 
wife  the  virtue  of  cooling  by  facilitating  and  favouring  evapora- 
tion. 

Warm  and  dry  air  is  beft  fuited  to  form  a  refrefhing  current, 
becaufe  it  is  more  calculated  to  dlfTolve  and  abforb  humidity  j 
moifl:  air  is  lefs  proper,  becaufe  it  is  already  faturated. — Hence 
the  necefTity  of  frequently  renewing  the  air  to  prefcrve  the  cool- 
nefs  of  our  apartments. 

Thefe  principles  have  a  nearer  relation  to  medicine  than  is 
generally  fuppofed.  We  find  that  almofl  all  fevers  end  in  per- 
fpirations,  which,  befide  the  advantage  of  expelling  the  morbifick 
matter,  poffefslikcwife  that  of  carrying  off  the  matter  of  heat, 
and  reiioring  the  body  to  its  common  temperature.  The  phyfi- 
cian  who  is  defirous  of  moderating  the  excefs  of  heat  in  the 
body  oi  a  patient,  ought  to  maintain  the  air  in  that  difpofition 
which  is  moft  fuitablc  to  his  views.     * 


Genera!  P^reperties  of  Heat.  it 

IChe  ufc  of  volatile  alkali  is  univerfally  acknowledged  to  be  of 
advantage  in  burns,  the  tooth-ache,  &c.  May  not  thefe  effc£}:s 
be  attributed  to  the  volatility  of  this  fubftance,  which  quickly 
combining  with  heat,  carries  it  off,  and  leaves  an  imprefiion  of 
cold  ? — Ether  is  a  fovcreign  i-emedy  for  the  colick.  Does  not 
its  virtue  depend  on  the  fame  principles  ? 

The  heat  which  has  entered  into  combination  with  bodies 
during  their  tranfition  from  the  folid  to  the  liquid  ftate,  or  from 
this  laft  to  the  aHriform  ftate,  may  be  again  exhibited  by  cauf- 
ing  thefe  fubftances  to  return  again  to  the  ftates  of  liquefa£lioii 
or  folidity.  In  a  word,  every  fubftance  which  pafles  from  the 
liquid  to  the  folid  ftate,  fufFers  its  latent  heat  to  efcape,  which  at 
this  inftant  becomes  free  or  thermometrical  heat. 

The  celebrated  Fahrenheit,  in  the  year  1724,  having  left  wa- 
ter expofed  to  a  colder  temperature  than  that  of  ice,  the  water 
remained  fluid  :  but  it  congealed  by  agitation  5  and  the  ther- 
mometer, which  marked  feveral  degrees  beneath  the  freezing 
point,  fuddenly  rofe  to  that  temperature.  Mr.  Treiwald  men- 
tions a  fimilar  fa£l  in  the  Tranfadlions  ;  and  Mr.  dc  Ratte 
Inade  the  fame  obfervations  at  Montpellier. 

Mr.  Baume  has  fliown,  in  his  enquiries  and  experiments  rela- 
ting to  feveral  lingular  phenomena  exhibited  by  water  at  the  in- 
ftant of  its  congelation,  that  feveral  degrees  of  heat  are  always 
developed  at  that  inftant. 

Gafeous  fubftances  are  maintained  in  the  aeriform  ftate  mere- 
ly by  the  heat  which  is  combined  with  them  ;  and  when  to 
thefe  fubftances,  thus  dilTolved  in  calorick,  another  body  is 
prefented,  to  which  they  have  a  veryftrong  affinity,  they  aban- 
don their  heat  to  unite  with  this  laft  fubftance  ;  and  the  calo- 
rick, thus  expelled  or  difengaged,  appears  under  the  form  of 
free  or  thermometrical  heat.  This  difengagement  of  heat,  by 
the  concretion  or  fixation  of  gafeous  fubftances,  was  obferved 
by  the  celebrated  Scheele,  as  may  be  feen  in  the  valuable  ex- 
periments which  form  the  bafis  of  his  Treatife  on  Air  and  Fire. 
Since  the  time  of  this  great  man,  rigorous  calculations  have 
been  made  of  the  quantity  of  latent  heat  exifting  in  each  of 
thefe  gafes  :  we  are  indebted  to  MefTrs.  Black,  Crawford, 
Wilcke,  De  la  Place,  Lavoifier,  ^c.  for  many  excellent  refearch^ 
es  on  this  fubjeft. 


82  Properties  and  Effects  of  Lr^hf, 

ARTICLE  IL 

Concerning  Light. 

It  appears  that  Light  is  tranfmitted  to  our  eyes  by  a  peci^i- 
lar  fluid  which  occupies  the  interval  between  us  and  vifiblc 
bodies. 

Does  this  fluid  arrive  direcftly  from  the  fun  by  fuccefTive  e- 
miffions  or  eradiations  ?  or  is  it  a  peculiar  fluid  diilributed 
through  fpace,  and  put  in  aftion  by  the  fun's  rotary  motion, 
cr  by  any  other  caufe  ?  I  fhall  not  enter  into  any  difcuflion  up- 
on  this  fubjed,  but  fhall  confine  myfelf  to  point  out  the  phe- 
.jiomcna. 

A.  The  motion  of  light  is  fo  rapid,  that  it  pafTes  through 
.nearly  eighty  thoufand  leagues  in  a  fecond. 

B.  The  elafl:icity  of  the  rays  of  light  is  fuch,  that  the  angk- 
of  refle£lion  is  equal  to  the  angle  of  incidence. 

C.  The  fluid  of  light  is  ponderous  :  for  if  a  ray  of  light  be 
received  through  a  hole  in  a  window- Ihutter,  and  the  blade  of 
.a  knife  be  prcfented  to  it,  the  ray  is  diverted  from  a  right  line, 
and  is  inflecled  towards  the  body.  This  circumftance  (hows 
that  it  obeys  the  law  of  attraction  and  fufficiently  authorizes  us 
to  clafs  it  among  other  bodies  of  this  nature. 

D.  The  great  Newton  fucceeded  in  decompofing  the  folar 
light  into  feven  primitive  rays,  which  prefent  themfelvcs 
in  the  following  order  :  red,  orange,  yellowy  green,  bine,  indi- 
go, violet.  Dies  prefent  us  with  only  three  colours,  which  are 
red,  blue,  and  yellow  :  the  combinations  and  proportions  of 
thefe  three  principles  form  all  the  Ihades  of  colour  with  which 
the  arts  are  enriched.  Philofophers  have  maintained  that  a- 
mong  the  folar  rays  there  are  three  primitive  colours. — ^See  Les 
Recherches  de  M.  Marat. 

All  natural  bodies  may  be  confidered  asprifms  which  decom- 
pofe  or  rather  divide  the  light.  Some  refleift  the  rays  without 
producing  any  change  and  thefe  are  white  ;  others  abforb  them 
all,  and  caufe  abfolute  blacknefs  :  the  greater  or  lefs  affinity  of 
the  feveral  rays  with  various  bodies,  and  perhaps  likewife  the 
difpofition  of  the  pores,  is  no  doubt  the  caufe  that,  when  a  pen- 
cil falls  upon  a  body,  fome  rays  enter  into  combination,  while 
others  arc  refletted  ;  and  it  is  this  which  aflrbrds  the  diverfity 
of  colours,  and  the  prodigious  variety  of  (hades  under  which 
bodies  appear  to  our  eyes. 

We  can  no  longer  confine  ourfclves  to  confider  light  as  a 
merely  phyfical  fubftance  j  the  chemill   perceives  it^  influence 


Properties  and  EffeEls  of  Light.  8 


:> 


In  mofl  of  his  operations,  and  finds  it  necefTary  to  attend  to  its 
.ft£lion,  which  modifies  his  refults  :  andjts  efFedsare  no  lefs  ev- 
ident in  the  various  phenomena  of  nature,  than  in  the  experi- 
ments performed  in  our  laboratories. 

We  fee  that  vegetation  cannot  take  place  without  light. 
Plants  deprived  of  this  fluid  become  pale  *,  and  when  in  hot- 
houfes  the  light  comes  to  them  from  one  part  only,  the  vegeta- 
bles incline  towards  the  aperture,  as  if  to  fliow  the  neceifity  of 
this  beneficial  fluid. 

Without  the  influence  of  light,  vegetables  would  exhibit  but 
one  lifelefy  colour  ;  they  are  deprived  of  their  beautiful  (liades 
by  the  interception  of  this.luminous  fluid.  On  thefe  principles 
celery,  endive,  and  other  plants,  are  bleached. 

Vegetables  are  not  only  indebted  to  the  light  for  their  colour, 
but  likewife  for  their  fmell,  tafte,  combuftibility,  maturity,  and 
the  refinous  principle,  which  equally  depend  upon  this  fluid. 
Hence  it  is,  no  doubt,  that  aromatick  fubftances,  refins,  and  vol- 
aj:ile  oils,  are  the  inheritance  of  fouthern  climates,  where  |:he 
M^ht  is  more  pure,  confl.ant  and  intenfe. 

We  fee,  hkewife,  that  the  influence  of  light  is  evident  in  oth- 
er beings  :  for,  as  Mr.  Dorthes  has  obferved,  worms  and  grubs, 
which  live  in  the  earth  or  in  wood,  are  of  a  whitiih  colour. 
The  birds  and  flying  infe6ls  of  the  night,  are  likewife  diitinguifli- 
able  from  thofe  of  the  day  by  the  want  of  brilliancy  of  colour  ; 
and  the  diflercnce  is  equally  marked  between  thofe  of  the  north 
and  of  the  fouth. 

A  very  altonifliing property  of  light  upon  the  vegetable  kingdom 
is,  that  when  vegetables  are  expofed  to  open  day-light,  or  to  thp 
fun's  rays,  they  emit  vital  air.  We  fhall  again  attend  to  ail  thefe 
phenomena  when  we  come  to  treat  of  the  analyfis  of  vegetables. 

The  fine  experiments  of  Scheele  and  Berthollet  have  (liewii 
that  the  abfence  or  prefence  of  light  has  an  aftonifliing  effedt 
upon  the  refult  of  chemical  experiments.  Light  difengages 
vital  air  from  feveral  fluids,  fuch  as  the  nitrick  acid,  the  oxigen^ 
ated  marine  acid,  &c.  Ic  reduces  the  oxides  or  calces  of  gold, 
filver,  &c.  It  changes  the  nature  of  oxigenated  muriates,  ac- 
cording to  the  obfervations  of  Mr.  Berthollet.  Light  likewife 
determines  the  phenomena  of  vegetation  exhibited  by  fahne  fo- 
lutions,  as  I  have  (hewn.  From  all  which  circumftances  it  is 
evident  that  we  ought  to  attend  to  the  ete(St  of  this  agent  in 
almod  all  our  operations- 

"  Organization,  fenfation,  fpontaneous  motion,  and  life,  exifl: 
only  at  the  furface  of  the  earth,  and  in  places  expofed  to  light  : 
we  might  aflirm  that  the  flame  of  Promctheus's  torch  was  the 
expreflkn  of  a  philofophical  truth  which  did  not  efc3pe  the  an4- 


$4  Origin  of  Sulphur, 

cients.  Without  light,  nature  was  lifelefs,  inanimate,  and  dead  : 
a  benevolent  God,  by  producing  light,  has  Ipread  organizational 
fcnfation  and  thought  over  the  furface  of  the  earth."— -Element- 
ry  Treatife  of  Chemillry  by  Mr.  Lavoifier. 

We  ought  not  to  confound  the  folar  light  with  the  light  of 
our  furnaces  •,  the  light  of  thefe  has,  as  I  am  convinced,  very 
evident  efFedls  in  certain  phenomena  ;  but  thefe  effects  are  flow, 
and  fcarcely  comparable  with  thofe  of  the  folar  light. 

Although  heat  often  accompanies  light,  the  phenomena  we 
have  mentioned  cannot  be  attributed  to  mere  heat.  fleat  may 
indeed  modify  them  where  it  exifts,  but  moil  afluredly  it  cannot 
produce  them. 


CHAPTER  il. 

Concerning  Sulphur, 

WE  are  obliged  to  place  Sulphur  among  the  elements,  though 
our  predeceflbrs  pretended  to  have  determined  its  conftituent 
principles.  This  proceeding  would  appear  to  be  retrograde,  if 
it  were  not  evident  that  the  correction  of  miftakes  is  a  real  ad- 
vancement in  fcience. 

The  ancients  ufed  the  word  fulphur  to  denote  every  com- 
buftible  and  imflamniable  fubftance.  Accordingly  we  find,  ii; 
all  their  writings,  the  expreflions  fulphur  of  metals,  fulphur  of 
animals,  fulphur  of  vegetables,  &c. 

Stahl  affxgneth  a  determinate  value  to  the  denomination  of 
gulphur ;  and  fince  the  time  of  this  celebrated  chemift  we  have 
confined  the  name  to  denote  a  body  of  an  orange-yellow  colour, 
dry,  brittle,  capable  of  burning  with  a  blue  flame,  and  exhaling 
a  penetrating  odour  during  combuIUon  :  when  rubbed,  it  be- 
comes eledlrick ;  and  by  a  light  preflnre  in  the  hand  it  cracks, 
and  becomes  reduced  to  powder. 

It  appears  that  fulphur  is  formed  by  the  decompofitlon  of  ve- 
getables and  animals.  It  has  been  found  on  the  walls  of  necef- 
fary-houfes  ;  and  when  the  ditch  of  the  Porte  St.  Antoine,  at 
Paris,  was  cleared,  a  confiderable  quantity  was  mixed  with  the 
decayed  remains  of  vegetable  and  animal  fubfl:ances,  that  had  fill- 
ed the  ancient  ditches,  and  there  putrefied. 

Mr.  Deyeux  has  likewife  proved,  that  fulphur  exifl:s  naturally 
in  certain  plants,  fu(:h  as  patientia,  cochlearia,  &c.  His  pro- 
ceflfes  for  extradling  it  confift  in — i.  The  wafhed  root  mult  be 
reduced  by  rafping  into  a  fine  pulp ;  this  mufl:  be  waflied  in 
cold  water,  and  paflied  through  a  fieve  or  gjoth  of  an  open  tex- 


Proceffes  for  extraSiing  Sulphur,  9§ 

ture  :  the  fluid  pafles  in  a  turbid  ftate,  and  depofites  a  precipi^ 
tate,  which  when  dried  proves  the  exiftence  of  fulphur.  2. 
The  pulp  may  be  boiled,  and  the  fcuni  afforded  by  the  ebullition 
afterwards  dried  :  the  fcum  contains  fulphur.  Several  fpecies 
of  rumex,  confounded  under  the  name  of  Patience,  do  not  con- 
tain fulphur.  I  have  obtained  it  from  the  rumex  patientia  L, 
M'hich  grows  on  the  mountains  Cevennes,  and  is  the  fame  which 
is  ufed  at  Paris.  M.  J^e  Veiliard  obtained  fulphur  by  fuffering 
vegetable  fubftances  to  putrefy  in  well-water.  Sulphur  is  a- 
bundantly  contained  in  coal  mines  ;  it  is  found  in  combination 
with  certain  metals  j  it  appears  almoft  always  where  vegetable 
decompofition  takes  place  ;  it  forms  the  greater  part  of  thofe 
pyritous  and  bituminous  fchifti  which  occupy  the  focus  of  vol- 
canos ;  it  is  fublimed  in  thofe  places  where  the  pyrites  are  de- 
compofed  ;  it  is  thrown  out  by  fubterrancous  fires  ;  and  is  found 
in  greater  or  lefs  quantities  in  volcanick  diftri(5ls.  Much  has 
beeq  faid  concerning  fhowers  of  fulphur  ;  but  it  is  at  prefent 
well  known  that  this  errour  has  chiefly  arifen  from  the  powder 
of  the  Itamina  of  the  pine,  which  is  carried  to  great  diftances. 
Henckel  faw  the  furface  of  a  marfh  entirely  covered  with  this 
powder. 

The  known  procelTes  for  cjftracfling  fulphur  in  the  large  way, 
and  applying  it  to  the  purpofes  of  commerce,  confift  in  difeu- 
gaging  it  from  the  pyrites  or  fulphures  of  copper,  or  of  iron,  by 
methods  poiTcfTmg  various  degrees  of  fjmplicity  and  economy. 
On  this  fubjed:,  the  Pyritology  of  Hencke},  Macquer's  Chemical 
Dictionary,  and  the  Metallurgical  Trads  of  Mr.  Jars,  may  be 
confulted. 

In  Saxony  and  Bohemia  the  ores  of  fulphur  are  diftilled  in 
earthen  tubes  difpofed  in  a  gallery.  The  l^ulphur  which  is  dif- 
engagcd  by  the  heat  pailes  into  receivers  placed  without,  and  in 
which  care  is  taken  to  keep  a  fuflicient  quantity  of  water. 

At  Rammelfburg,  at  St.  Bel,  t\'c.  large  heaps  of  pyrites  are 
rnade,  which  are  decompofed  by  a  gentle  heat,  at  lirlt  applied 
to  the  mafs  from  a  ftratum  of  cdmbuflible  matter  upon  which  it 
is  placed.  The  heat  is  afterwards  kept  up  by  the  adion  of  the 
pyrites  amon^fl:  each  other.  The  fulphur  which  exhales  cannct 
eicape  laterally,  becaufe  c^re  is  taken  to  cover  the  fides  with 
earth.  It  therefore  riies  to  the  fummit  of  the  truncated  pyra- 
mid, where  it  is  goUedcd  in  fmall  cavities  made  for  that  pur- 
pofe.  The  }ieat  of  this  part  is  fufficient  to  keep  the  fulphur  in 
ii  fluid  Hate  5  and  it  is  taken  out  from  time  to  time  with  ladles. 
Almoll  all  the  fulphur  ufed  in  France  comes  from  the  Solfa- 
tara.  This  volcanick  country  every  where  exhibits  marks  of 
the  agency  of  fub^erraueous  fire.    The  e^iormous  mafles  of  py- 


S6  Anahjis  of  Sulphur, 

rites  which  are  decompofed  in  the  bowels  of  the  enrth  produce 
heat,  which  fublimes  part  of  the  fulphur  through  apertures 
which  the  lux,  and  the  effort  of  the  vapours,  have  opened  in  all 
parts.  The  earths  and  flones  which  contain  fulphur  are  didilled  -, 
and  it  is  the  refult  of  this  diltillation  whicli  is  called  Crude  Sul- 
phur. 

The  crude  fulphur  is  tranfported  into  France  by  the  way  of 
Marfeilles,  where  it  receives  the  necelFary  preparations  tq  render 
it  fultabie  to  various  purpofes.  i.  It  is  reduced  into  Iticks  or 
rolls,  by  fufing  it,  and  pouring  it  into  moulds  :  or,  2.  It  is 
formed  into  flowers  of  brimflone  by  fubliming  it  with  a  gentle 
Iieat,  and  collefting  this  fulphureous  vapour  in  a  very  clofe 
chamber  of  confiderable  extent.  This  very  pure  and  finely  di- 
vided fulphur  is  dillinguiflied  by  the  narns  of  Flowers  of  Brim- 
flone, or  Sublimed  Sulphur. 

Sulphur  enters  into  fufion  by  a  moderate  heat  ;  and  if  the 
moment  be  feized  in  which  the  furface  congeals,  and  the  liquid 
fulphur  contahied  beneath  that  furface  be  then  poured  out,  the 
internal  cavity  will  exhibit  long  needle-formed  cryftals  of  an  oc- 
tahedral figure.  This  procefs,  contrived  by  the  famous  Rouelle, 
has  been  applied  to  the  cryflallization  of  almolt  all  the  metals. 
Sulphur  is  found  nat  *rally  cryftaUized  in  Italy,  at  Conilla  near 
Cadiz,  he.  Its  ufual  form  iso61ahedral  :  but  I  have,  neverthe- 
kfs,  it^ii  cryfbals  of  fulphur  in  perfedl:  rhomboids. 

Stahl  thought  that  he  had  proved,  by  analyfis  and  fynthefis, 
that  fulphur  *is  formed  by  the  combination  of  his  phlogiftou 
with  the  fulphurick  acid.  The  happy  feries  of  proofs  which  he 
has  left  behind  him  for  the  eltablifhment  of  his  opinion,  has  ap- 
peared fo  complete,  that,  fince  the  time  of  this  great  man,  his 
dodrine  has  confiantly  been  admitted  as  founded  on  abfolute 
proof.  This  example  was  even  urged  as  an  inftance  to  (hew 
how  high  a  degree  of  evidence  the  chemical  analyfis  was  capable 
of  affording.  But  our  difcoveries  refpecling  gafeous  fubflances 
have  fhewn  us,  that  the  ancients  were  neceliariiy  led  into  er- 
rour  for  want  of  that  knowledge.  The  immenfe  refearches  of 
the  moderns  into  the  compofition  of  acids,  have  ihewn  that  thsfe 
fubftances  are  decompofed  in  a  variety  of  operations  ;  and  this 
revolution  in  the  ftate  of  our  knowledge  mull  have  produced  11 
fmiiiar  change  in  our  methods  of  explaining  the  phenomena. 
An  examination  of  the  principal  experiments  of  Stahl,  upon 
which  his  do6lrine  efTentially  depends,  will  fu^hciently  Ihew  the 
truth  of  what  we  have  afierted. 

If  one  third  part  of  charcoal,  and  two  thirds  of  fulphate  of 
pot-afh,  or  vitriolated  tartar,  be  mixed  and  fufed  in  a  cruci- 
ble^ the  produdl  is  (liver  of  fulphur)  fulphure  of  pot-  afh.     If  thiis 


Carhne,  gy' 

fiilphurfebediflblved  in  water,and  the  alkili  be  engaged  by  adding 
a  few  drops  of  fulphurick  acid,  a  precipitate  is  afForded,  which 
confiftsof  true  fulphur  :  "  whence,"  fays  Stahl,  "  the  fulphur  is 
a  combination  of  phlogifton,  or  the  inflammable  principle  of  the 
charcoal  with  the  fulphurick  acid."  The  experiment  was  true,  bu^ 
the  confequence  is  abfurd  ;  becaufe  it  would  follow  that  the  ful- 
phurick acid  which  was  added,  mult  have  poflefled  the  property 
of  difplacing  fulphurick  acid  united  to  the  alkali.* 

If  Stahl  had  more  ftri£lly  analyfed  the  refult  or  product:  of* 
this  operation,  he  would  have  been  convinced  that  it  does  not 
contain  a  particle  of  fulphurick  acid. 

If  he  had  been  poflelled  of  the  power  of  operating  in  clofed 
veflels,  and  of  colle£ling  the  gafeous  fubftanccs  which  are  difen- 
gaged,  he  would  have  obtained  a  large  quantity  of  carbonick 
acid,  which  arifes  from  the  combination  of  the  oxigene  of  the 
fulphurick  acid  with  the  charcoal. 

If  he  had  expofed  his  liver  of  fulphur  to  the  air  in  clofed  vef- 
fels,  he  would  have  feen  that  the  vital  air  is  abforbed,  that  the 
fulphure  is  decompofed,  and  that  the  fulphateof  pot-afh,  orvit- 
riolated  tartar  is  formed  ;  which  proves»the  recompofition  o£ 
the  fulphurick  acid. 

If  charcoal  be  molftened  with  fulphurick  acid  or  oil  of  vitriol, 
and  then  expofed  to  diftillation,  the  produces  are  carbonick  acid 
or  fixed  air,  fulphur,  and  much  fulphureous  or  volatile  vitriolick 
acid. 

The  experiments  of  Stahl  exhibit  the  mod  perfecb  demonftra- 
tion  of  the.  decompo.fition  of  the  fulphurick  acid  into  fulphur  and 
oxigene  ;  and  it  is  not  neceflary,  in  the  explanation  of  them', 
either  to  fuppofe  the  exiftence  of  an  imaginary  being,  or  to  fup- 
pofe  that  fulphur  is  a  compounded  body. 


CHAPTER    HI. 

Concerning  Carbone. 

PURE  charcoal  is  Called  Carbone  in  the  new  Nomenclature, 
This  fubftance  is  placed  among  fimple  bodies,  becaufe  no  experi- 
ment h:is  hitherto  ihown  the  poffibiiity  of  decompofing  it. 

*  without  pretending,  on  the prefent  occafion,  to  tl'fpute  either  for  or 
agninll  phlogifton,  I  ihall  ohfcrve  that  this  arguniert  J-*  amon^?  the  many 
p.trah>giln)s  ur)^cd  (.n  both  fides  in  this  conrroveriy.  •  If  there  he  any  dif- 
ficulty in  conccivirf;  how  dephlogiilicatcd  fulphur,  or  pure  vitriolick  acid, 
may  difpiace  phlcgilticated  vitriolick  acid,  or  fu!phur,  the  f.'mc  will  apply  r» 
the  oppuCue  thtory,  n'hirh  aflerts  that  aerated  fu!i^?iur,  or  vitriolick  acid,  dif- 
places  dc-:itratcd  vittiolick  acid,  or  purs  fulphur.    T. 


is  Con'Oerfion  of  Bodies i 

^^'  Carbone  exifts  ready  formed  In  vegetables.     It  may  be  clears 

ed  of  all  the  volatile  and  oily  principles  by  diftillation  ;  and,  by 
fubfequent  waOiing  in  pure  water,  it  may  be  deprived  of  all  the 
falts  which  are  mixed  and  confounded  with  it. 

When  it  is  required  to  procure  carbone  in  a  ftate  of  great 
purity  it  niuffc  be  dried  by  ftrong  ignition  in  a  clofed  vefTel  : 
this  precautioa  is  neceflary :  for  the  lad  portions  of  water 
adhere  with  fudi  avidity,  that  they  are  decompofed,  and  afford 
hydrogenous  gas  and  carbonick  acid. 

Carbone  exifts  likewife  in  the  animal  kingdom  :  It  may  be; 
extrafled  by  a  procefs  fimilar  to  that  which  we  have  defcribed  ; 
but  its  quantity  is  fmall.  It  appears  in  the  form  of  a  light 
fpungy  mafs,  difficultly  confum^ed  in  the  air,  and  mixed  with  a 
great  quantity  of  phofphates,  and  even  of  foda. 

Carbone  is  likewife  found  in  plumbago,  of  which  it  is  one  of 
the  principles. 

We  (hall  treat  more  fully  of  this  fubfiance  in  \}az  analyfis  of 
Vegetables.  But  thefe  concife  ideas  are  fufficient  to  enable  us 
to  proceed  in  our  account  of  its  combinations,  which  is  indeed 
the  only  objed  of  the  prefent  fliort  enumeration  of  its  properties. 


SECTION  V. 

Concerning  Cafes,  or  the  Solution  of  certain  Principles  in  Calorick,  at  th: 
Temperature  of  the  Atmoiphere. 


\ji  ALORICE,  in  Its  combination  with  bodies,  volatili- 
izes  Tome  of  them,  and  reduces  them  to  the  aeriform  ftate.  The 
|)ermanence  in  this  ftate  in  the  temperature  of  the  atmofphere 
conftitutes  the  gafes  ;  fo  that,  to  reduce  a  fubftanee  to  the  ftate 
of  gas,  con  fills  in  difTolving  it  in  calorick. 

Calorick  combines  with  various  bodies,  with  greater  or  lef^ 
facility  ;  and  we  are  acquainted  with  feverai  that,  at  the  temper- 
ature  of  the  atmofphere,  are  conftantly  in  the  ftate  of  gas : 
there  are  others  which  pafs  to  this  ftate  at  fome  degrees' higher, 
and  thefe  are  called  Volatile  or  Evaporable  fubftances.  They 
differ  from  fixed  fubftances,  becaufe  thefe  laft  are  not  volatilized 
but  by  the  application  and  combination  of  a  ftrong  dofe  of  calor- 
ick. 

It  appears  that  all  bodies  do  not  indifcriminately  require  the 
fame  quantity  of  calorick  to  affuine  the  gafeous  ftate  5   and  wd 


hy  Heat  into  Gafes.  ^9 

!I  fee  that  this  proportion  may  be  deduced  from  the  fixation 
...A  concretion  of  thefe  gafeous  fubftances. 

To  reduce  any  fuhftance  to  the  ftate  of  gas,  the  application  of 
calorick  may  be  "made  in  various  manners. 

The  more  fimple  method  confills  in  placing  the  body  in  con- 
ta£l  with  another  body  which  is  heated.  In  this  fituation,  the 
heat  on  one  hand  diminifhes  the  affinity  of  aggregation  or  com- 
pofition,  by  feparating  the  conftituent  principles  to  a  greater  dif^ 
tance  from  each  other  ;  on  the  other  hand,  the  heat  unites  to  the 
principles  with  which  it  has  the  ftrongeft  affinity,  and  volatiHzes 
them.  This  procefs  is  according  to  the  method  of  fimple  affin- 
ities ;  for  it  in  fa£l  confifts  of  the  exhibition  of  a  third  body, 
which,  prefented  to  a  compound  of  feveral  principles,  combines 
with  one  of  them,  and  carries  it  off. 

The  method  of  double  affinity  may  likewife  be  ufed  to  con- 
vert any  fubftance  into  the  gafeous  form  j  and  this  is  what  hap- 
pens when  we  caufe  one  body  to  acl  upon  another  to  produce 
a  combination,  in  which  a  difengagement  of  fome  gafeous  prin- 
ciples takes  place.  If  I  pour,  for  example,  the  fulphurick  acid 
upon  the  oxiode  of  manganefe,  the  acid  combines  with  the  met- 
al, while  its  calorick  feizes  the  oxigene,  and  rifes  with  it.  This 
principle  takes  place  not  only  in  this  inftance,  but  on  all  other 
occafions  wherein  an  operation  being  performed  without  the 
r^pplication  of  heat,  there  is  a  production  of  vapour  or  gas. 

The  various  dates  under  which  bodies  prefent  themfelves  to 
our  eyes,  depend  almoft  entirely  upon  the  different  degrees  o£ 
combination  of  calorick  with  thofe  fame  bodies.  Fluids  do  not 
differ  from  folids,  but  becaufe  they  conftantly  poffefs,  at  the 
temperature  of  the  atmofphere,  the  dofe  of  calorick  which  is» 
requifite  to  maintain  them  in  that  ftate  ;  they  congeal  and  pafs 
to  the  concrete  ftate  with  greater  or  lefs  facility,  accordingly  as 
the  requifite  quantity  of  calorick  is  more  or  lefs  confiderable. 

All  folid  bodies  are  capable  of  paffing  to  the  gafeous  ftate  ; 
and  the  only  difference  which  exifts  between  them  in  this  refpedt 
i?5,  that  a  dofe  of  calorick  is  required  for  this  purpofe,  which  i$ 
governed — i.  I3y  the  affinity  of  aggregation,  which  conned^ s 
their  principles,  retains  tl^em,  and  oppofes  itfelf  to  a  new  combi- 
nation. 2.  By  the«  weight  of  the  conftituent  parts,  which  ren- 
ders their  volatilization  more  or  lefs  difficult.  3.  By  the  agree- 
ment and  attraction  between  the  calorick  and  the  folid  body, 
which  is  more  or  lefs  ftronjr- 

.  All  bodies,  whether  folid  or  liquid,  when  they  come  to  be 
volatilized  by  heat,  appear  in  two  (tates — that  of  vapour,  of  that 
of  gas.  '* 

M 


1 

^^  Bxpermenis  on  Gafes, 

In  the  firfi  cafe,  thefe  fubftances  lofe,  In  a  fhort  time,  thtf  ca* 
lorick  which  raifed  them,  and  again  appear  in  their  original 
form  the  moment  the  calorick  finds  colder  bodies  to  combine 
ivith ;  but  it  is  rare  that  the  bodies  thus  divided  refume  their 
original  confidence.     This  fir  ft  ft  ate  is  that  of  vapour. 

In  the  fecond  cafe,  the  combination  of  calorlck  with  the  vol- 
Milized  fubftance  is  fuch,  that  the  ordinary  temperature  of  th& 
atmofphere  is  infufficient  to  overcon>e  this  unioi^.  This  ftate 
conftitutes  the  gafes. 

When  the  combination  of  calorick  with  any  fubftance  is 
fuch  that  a  gas  is  produced,  thefe  invifible  fubftances  may  be 
managed  at  pleafure,  by  the  affiftancc  of  apparatus  appropriated 
within  our  time  to  thefe  ufes.  Thefe  apparatus  are  known  by 
the  nartie  of  Pneumato-chemick,  Hydro-pneumatiek  appara- 
tus, &c. 

The  prieumato-chemical  apparatus,  in  general,  confifts  of  ^ 
wooden  vefrel,  ufually  of  a  fquare  form,  and  lined  with  lead  oi^ 
tin  :  two  or  three  inches  beneath  the  upper  edge  there  is  formed 
a  groove,  in  which  a  wooden  plank  Hides,  having  a  hole  in  the 
middle,  and  a  notch  in  one  of  its  fides  •,  the  hole  is  made  i«» 
the  centre  of  an  excavation  made  in  the  ftielf,  of  the  figure  of  a. 
funnel. 

This  vefTel  is  filled  with  water  or  mercury,  according  to  thsi. 
nature  of  the  gafes  operated  upon.  There  are  fome  which  eafi^ 
iy  combine  with  water,  and  therefore  require  to  be  received  over 
mercury. 

The  gafes  may  be  extracted  in  various  manners. 

When  they  are  difengaged  by  fire,  a  recurved  tube  is  adapted 
to  the  neck  of  the  retort,  one  extremity  of  which  is  plunged  in 
^e  water  or  the  mercury  of  the  pneumato-chemical  veflel,  ancf 
opens  beneath  the  aperture  in  t!ie  fhelf,  which  is  in  the  form  of* 
a  funnel.  The  jundtion  of  the  tube  with  the  neck  of  the  retort 
is  fecured  with  the  ufual  lute  ;  a  vefiel  filled  with  the  liquid  of 
the  eiftern  is  inverted  upon  the  ihelf  over  the  aperture.  When 
the  gas  is  difengaged  frc^m  the  materials  in  the  retort,  it  appears 
in  the  form'  of  bubbles,  which  rife,  and  gain  the  fuperlour  part 
of  the  inverted  veflel.  When  all  the  water  is  difplaced,  and  the 
Bottle  is  full  of  gas,  it  is  withdrawn,  by  adapting  a  glafs  plate 
to  its  orifice  to  prevent  its  diflipation  :  it  may  then  be  poured 
from  one  veflel  to  another,  and  fubje6ted  to  a  variety  of  experi- 
ments to  afcertain  its  nature. 

When  the  gafes  are  difengaged  by  means  of  acids,  the  mijt- 
ture  which  is  defigned  to  afford  them  is  put  into  a  bottle  with 
a  recurved  tube  fitted  to  its  neck  -,  and  this  tube  Is  plunged  in 
the  eiftern  in  fuch  a  manner,  that  the  bubbles  of  gas  may  pafs-. 


Hydrogenous  Qas*  ^f 

«5  in  the  former  experiment,  through  the  apertarc  of  the  funnel 
ia  the  flielf. 

The  procefles  at  prefent  ufed  to  extract  the  gafes,  and  to  an- 
alyfe  them,  are  fimple  and  commodious  :  and  the fe  procefles  have 
Singularly  contributed  to  our  acquifition  of  the  knowledge  of 
thefe  aeriform  fubftances,  whofe  difcovery  has  produced  a  reyo-^ 
iution  in  chemiftry. 


CHAPTER    I. 

Concerning  Hydrogenous  Gaff  or  InJlarnmaUe  Air^ 

INFLAMMABLE  Air  is  one  of  the  conftituent  parts  of  war 
tcr  -,  a  circumftance  which  has  entitled  it  to  the  denomination 
of  Hydrogenous  Gas.  Its  property  of  burning  with  vital  air, 
hascaufedit  to  be  diftinguifhed  by  the  name  of  Inflammable 
Air. 

Hydrogenous  gas  has  been  procured  long  fince.  The  famous 
philofophical  candle  attefts  the  antiquity  of  this  difcovery  j  an^ 
the  celebrated  Hales  obtained  from  moll  vegetables  2^n  air  which 
took  fire. 

Hydrogenous  gas  may  be  extracted  from  all  bodies  in  which 
it  is  a  conftituent  part  ;  but  the  purcft  is  that  afforded  by  de- 
compofition  of  water,  and  it  is  this  fluid  which  ufually  affords 
it  in  our  laboratories.  For  this  purpofe  the  fulphurick  acid  i$ 
poured  upon  iron,  or  zinc  ;  the  water,  which  ferves  as  a  vehi- 
cle for  the  acid,  is  decompof^d  on  the  metal,  its  oxigene  com- 
bines with  it,  while  the  hydrogenous  gas  efcapes.  This  expla- 
nation, however  contrary  to  the  ancient  notion,  is  not  the  lefs 
"a  demonftrated  truth  ;  in  fa£l,  the  metal  exifts  in  the  ftate  of 
an  oxide  in  its  folution  by  the  fulphurick  acid,  as  m^y  be  proved 
by  precipitating  it  with  pure  vegetable  alkali  :  on  the  other 
hand,  the  acid  itfelf  is  not  at  all  decompofed  ;  fo  that  the  oxi- 
genous  gas  cannot  have  been  afforded  to  the  iron  but  by  the 
water.  Water  may  be  decompofed  likewife  ftill  more  diredly 
by  throwing  it  upon  iron  ftrongly  heated  ;  and  hydrogenous 
gas  may  be  obtained  by  caufing  water  to  pafs  through  a  tube  of 
iron  ignited  to  whitenefs. 

The  hydrogenous  gas  may  be  extra6led  by  the  fimple  diftil- 
lation  of  vegetables.  Vegetable  fermentation,  and  animal  pu- 
trefaftion,  likewife  produce  this  gafeous  fubftance. 

The  properties  of  this  gas,  are  as  follow  ; 

A.  Hydrogenous  gas  has  a  difagreeable,  ftinking  odour.  Mr. 
Kirwan  has  obferved,  that  when  it  is  extracted  over  mercury,  it 


92  Hydrogenous    Gas, 

has  fcarcely  any  fmell.  It  contains  half  its  weight  of  water,  and 
lofes  its  fmell  the  moment  it  is  deprived  of  this  additional  fub- 
ftance. 

Kirwan  has  hkewifc  obferved,  that  the  volume  of  hydroge- 
nous gas  is  one  eighth  larger  when  received  over  water  than 
when  received  over  mercury. 

Thefe  obfervations  appear  to  prove,  that  the  ofFcnfive  fmell  of 
this  gasarifes  only  from  the  water  it  holds  in  folution. 

B.  Hydrogenous  gas  is  not  proper  for  refpiration.  The  ab- 
be Fontana  affures  us  that  he  could  not  take  more  than  three 
infpirations  of  this  air  :  the  count  Morrozo  has  proved  that  an- 
imals perifli  in  it  in  a  quarter  of  a  minute.  On  the  other  hand 
fevcral  northern  chemifts  have  affirmed,  in  confequence  of  ex- 
periments made  on  themfelves,  that  hydrogenous  gas  might  be 
refpired  without  danger  ;  and  it  is  fome  years  fince  the  unfor- 
tunate Pilatre  du  Rozier  filled  his  lungs  with  it  at  Paris,  and 
fet  it  on  fire  during  the  expiration,  which  forms  a  very  curious, 
jet  of  flame.  It  was  remarked  to  him  that  the  abbe  Fontana 
had  objedled  againft  the  accuracy  of  the  Swedifli  chemifts. 
This  intrepid  philofopher  anfwered  the  obje£Hon,  by  mixing 
one  ninth  of  atmofpherical  air  with  very  pure  hydrogenous  gas. 
He  refpired  this  mixture,  as  ufual  ;  but  when  he  attempted  to 
iet  it  on  fire,  the  confequence  was  an  explofion  fo  dreadful,  that 
he  imagined  all  his  teeth  were  blown  out. 

This  oppofition  of  opinions,  and  contradiction  of  experi- 
ments, refpefting  a  phenomenon  which  feems  capable  of  unan- 
fwerable  decifion  by  one  fingle  experiment,  induced  me  to  have 
recourfe  to  trial,  to  fix  my  own  ideas  on  the  fubje£l. 

Birds  fucceflively  placed  in  a  veflel  of  hydrogenous  gas,  died, 
without  producing  thefmallefl  perceptible  change  in  the  gas  itfelf. 

Frogs  placed  in  forty  inches  of  hydrogenous  gas  died  in  the 
fpace  of  three  hours  and  a  half:  while  others  lived  fifty-five 
hours  in  oxigenous  gas  and  atmofpherick  air  ;  and  when  I  took 
them  out  flill  living,  the  air  was  neither  vitiated  nor  diminifhed. 
Numerous  experiments  which  I  have  made  upon  thefe  animals 
have  led  me  to  obferve  that  they  have  the  faculty  of  ftopping 
their  refpiration,  when  placed  in  any  noxious  gas,  to  fuch  a  de- 
gree, that  they  infpire  only  once  or  twice,  and  afterwards  fuf« 
j)end  every  function  on  the  part  of  the  refpiratory  organ.  ^ 

I  have  fince  had  occafion  to  obferve  that  thefe  animals  are  not 
reduced  into  a  putrid  mafs  by  remaining  in  hydrogenous  gas, 
as  was  affirmed  fome  time  a^o.  The  fafl  which  may  have  im- 
pofed  on  chemifts  who  related  this  circumftance,  is,  that  frogs 
are  often  enveloped  in  a  mucus  or  fanies,  which  appears  to  covt 
er  them  ;  but  they  exhibit  the  fiime  phenomenon  in  all  the  gafes, 


cr   hijlammahk    Air,  93 

After  having  tried  tlie  hydrogenous  gas  upon  animals,  I  de- 
termined to  refpire  it  myfelf  -,  and  I  found  that  the  fame  vol- 
ume of  this  air  might  be  feveral  limes  refpired  M'ithout  danger. 
But  I  obferved  that  this  gas  was  not  changed  by  thefe  opera- 
tions ;  whence  I  concluded  that  it  is  not  refpirable  :  for,  if  it 
were,  it  would  fuffer  a  change  in  the  lungs,  the  obje£l  of  refpi- 
ration  not  being  confined  to  the  reception  and  emiilion  of  a 
fluid  merely  *,  it  is  a  function  much  more  noble,  more  intereft- 
ing,  more  intimately  conneded  with  the  animal  economy  :  and 
we  ought  to  confider  the  lungs  as  an  organ  which  is  nouriflied 
by  the  air,  digefts  that  which  is  prefented  to  it,  retains  the  ben- 
eficial, and  rejeds  the  noxious  part.  Since,  therefore,  inflam- 
mable air  can  be  refpired  feveral  fucccffive  times  without  dan- 
ger to  the  individual,  and  without  any  alteration  or  change  in  it- 
i'elf,  we  may  conclude  indeed  that  inflammable  air  is  not  a  poi- 
fon,  but  that  it  cannot  be  confidered  as  an  :nr  eflentially  proper 
to  refpiration.  It  is  with  hydrogenous  gas  in  the  lungs,  as  with 
thofe  balls  of  mofs  and  refin  which  certain  animals  fwallow 
during  the  rigorous  feafon  of  the  winter.  Thefe  balls  are  not 
digeded,  fince  the  animals  void  them  at  the  return  of  fpring  : 
but  they  delude  hunger,  and  the  membranes  of  the  ftomach  are 
cxercifed  upon  them  without  danger,  in  the  fame  manner  as  the 
lungs  exert  themfelves  upon  the  hydrogenous  gas  prefented  to 
them. 

C.  Hydrogenous  gas  is  not  combuftible  alone  ;  it  does  not 
burn  but  by  the  concurrence  of  oxigene.  If  a  veflel  filled  with 
this  gas  be  reverfed,  and  a  lighted  taper  be  prefented  to  it,  the 
hydrogenous  gas  is  found  to  burn  at  the  furface  of  the  veflel  ; 
but  the  candle  is  extinguiflied  the  moment  it  is  plunged  lower. 
The  mod  inflammable  bodies,  fuch  as  phofphorus,  do  not  burn 
in  an  atmofphere  of  hydrogenous  gas. 

D.  Hydrogenous  gas  is  lighter  than  common  air.  One  cu- 
bick  foot  of  atmofphcrick  air  weighs  feven  hundred  and  twenty 
grains  ;  a  cubick  foot  of  hydrogenous  gas  weighs  feventy-tvvo 
grains.  The  barometer  being  at  29'  9,  and  the  thermometer 
60°  Fahrenheit,  Mr.  Kirwan  found  the  weight  of  this  air  to  that 
of  common  air  as  eighty-four  to  one  thoufand  •,  confequently 
it  was  about  twelve  times  as  light. 

Its  fpecifick  gravity  varies  very  much,  becaufe  it  is  difTicult  to 
obtain  it  conitantly  of  the  lame  degree  of  purity.  That  which 
is  extraifted  from  vegetables  contains  the  carbonicL  acid  and  oil, 
which  increafes  its  weight. 

This  levity  of  hydrogenous  gas  has  caufed  certain  pJiilofophers 
to  prefume  that  it  ought  to  arrive  at  and  occupy  the  fuperiour 
fart  of  our  atmofphere  ,  and  upon  this  fuppolition  the  moft  brill- 


94  Hepaikk  Gas, 

iant  conje(^urcs  have  been  made  refpe(fiing  the  influence  whicl^ 
a  ftratum  of  this  gas,  predominating  over  the  reft  of  the  atmof- 
phere,  ought  to  produce  in  meteorology.  They  were  not  aware 
that  this  continual  lofs  of  matter  is  not  agreeable  to  the  wife  e- 
conomy  of  nature.  They  did  not  obferve  that  this  gas,  during 
its  afcent  in  the  air,  combines  with  other  bodies,  more  efpecial]y 
pxigene,  and  that  water  and  other  products  are  the  refult  ;  the 
knowledge  of  which  muft  neceiTarily  lead  us  to  that  of  mof| 
meteors. 

The  theory  of  balloons,  or  aeroftatiek  machines,  is  founded 
on  this  levity  of  the  hydrogenous  gas. 

In  order  that  a  balloon  may  rife  in  th^  atmofpherc,  it  is  fuffi- 
crent  that  the  weight  of  the  balloon  itfelf,  and  the  air  it  inclo^ 
fes,  fliould  be  lefs  confiderable  than  that  of  an  equal  bulk  of  at- 
mofpherick  air  ;  and  it  muft  rife  till  jts  weight  is  in  equilibrip 
with  an  equal  volume  of  the  furrounding  ajr. 

The  theory  of  the  Montgolfiers  is  very  different  from  this. 
In  this  cafe  a  given  volume  of  atmofpherick  air  is  rarefied  by 
heat,  and  kept  feparated  from  the  common  mafs  by  a  hollow; 
veflel  of  cloth.  This  rarefied  fpace  may  therefore  be  confider- 
cd  for  a  moment  as  confiding  of  a  mafs  of  air  of  greater  levity, 
which  muft  neceffarily  make  an  effort  to  rife  in  the  atmofphere, 
and  carry  its  covering  along  with  it. 

E.  Hydrogenous  gas  exhibits  various  chara£lers,  according  to 
jts  degree  of  purity,  and  the  nature  of  the  fubftanccs  which  are 
mixed  with  it- 
It  feldom  happens  that  this  gas  is  pure.  That  which  is  afford- 
ed by  vegetables  contains  oil,  and  the  carbonick  acid.  The  in- 
flammable :^ir  of  marfhes  is  mixed  with  a  greater  or  lefs  quanti- 
ty of  carbonick  acid  ;  and  that  which  is  afforded  by  the  decom- 
pofition  of  pyrites  fometimes  holds  fulphur  in  folution. 

The  colour  of  hydrogene,  when  fet  on  fire,  varies  according 
to  its  mixtures.  One  third  of  the  air  of  the  lungs,  mijced  with 
the  inflammable  air  of  pit-coal,  affords  a  flame  of  a  blue  colour  % 
inflammable  air,  mixed  with  nitrous  air,  affords  a  green  colour  ; 
the  vapour  of  either  affords  a  white  flame.  The  vj^rious  mix- 
tures of  thefe  gafes,  and  the  degree  of  comprelfion  to  which 
they  are  fubjeded,  when  expreffed  out  of  an  aperture  in  order 
to  burn  them,  have,  in  the  hands  of  certain  operators,  aflbrded 
very  agreeable  illuminations,  well  deferving  the  attention  ol 
learned  and  curious  obfervers. 

F.  Hydrogenous  gas  pofleffes  the  property  of  difTolvImg  ful- 
phur. In  this  cafe  it  contrajSls  a  ftinking  Imell,  and  forins  he^^ 
patick  gas. 


iiepaiick  Gas.  ^j 

Mr.  Oengembr€  put  fulphur  into  inverted  vefTels  filled  with 
hydrogenous  gas,  and  diflblved  it  by  means  of  the  burnlng-glafs. 
The  hydrogenous  gas,  by  this  treatment,  obtained  all  the  char- 
adleriftick  properties  of  hepatick  gas. 

The  formation  of  this  gas  is  almoft  an  efFe£l  of  the  decompo* 
iition  of  water.  In  fa£l,  the  alkaline  fulphures,  or  livers  of  ful- 
phur, do  not  emit  any  difagreeablc  fmell  while  they  are  dry  ; 
but  the  moment  they  are  moiftened,  an  abominable  fmell  is 
perceived,  and  fulphate  of  pot-alh,  or  vitriolated  tartar,  begins 
to  be  formed.  Thefe  phenomena  prov6  that  the  water  is  decom-^ 
pofed  ;  that  one  of  its  principles  unites  to  the  fulphur,  and  vol- 
atilizes it }  while  the  other  combines  with  the  alkali,  and  form* 
a  more  fixed  produd. 

Sulphurated  hydrogenous  gas  may  be  obtained  by  diflblving 
the  fulphures  or  hepars  by  acids.  Thofe  acids  in  which  the  ox- 
igene  is  mod  adherent  difengage  the  greateft  quantity.  The 
muriatick  acid  produces  twice  as  much  as  the  fulphurick.  That 
■which  is  produced  by  this  laft,  burns  with  a  blue  flame  ;  bu^ 
that  which  is  difengaged  by  the  muriatick  acid,  burns  with  s^ 
yellowifh  white  flame. 

Scheele  has  taught  us  the  means  of  obtaining  this  gas  in  great 
abundance,  by  decompofing  artificial  pyrites,  formed  by  thre« 
parts  of  iron  and  one  of  fulphur,  to  which  fpirit  of  vitriol  is  added. 

The  natural  decompofition  of  pyrites  in  the  bowels  of  the 
earth  produces  this  gas  ;  which  efcapes  with  certain  waters^  and 
^communicates  peculiar  virtues  to  them. 

The  molt  general  properties  of  thefe  gafes  are  : 

1.  They  render  the  white  metals  black. 

2.  They  are  improper  for  refpiration. 

3.  They  impart  a  green  colour  to  fyrup  of  violets. 

4.  They  burn  with  a  light  blue  flame,  and  depofitc  fulphur 
by  this  combuftion. 

5.  They  mix  with  the  oxigenous  gas  of  the  atmofpherick  air* 
and  form  water  -,  at  the  fame  time  that  the  fulphur,  before  held 
an  folution,  falls  down."*  Hence  it  happens  that  fulphur  is  found 
in  the  channels  of  hepatick  waters,  though  their  aualyfis  does 
|aot  fliow  the  exiilence  of  an  atom  of  that  fubftance  held  in  fo- 
lution. 

6.  They  impregnate  water,  and  are  fparingly  foluble  in  that 
.fluid  ;  but  heat  or  agitation  diflipates  them  again. 

The  air  which  burns  at  the  furface  of  certain  fprings,  and 
forms  what  is  known  by  the  name  of  the  burning  fprings,  con- 
£fts  of  hydrogenous  gas  holding  phofphorus  in  folution.  It 
(jnells  like  putrid  fifti.  The  Pcre  Lampi  has  difcovered  one  of 
thefe  fprings  in  the  ifles  of  St.  Colombat.     Dauphiny  exhibars 


96'  Vital  A'n\ 

another  iimilar  fprlngat  the  diflance  of  four  leagues  from  Gre- 
noble. The  ignis  fatui  which  glide  along  burying-grounds> 
and  which  the  fuperilitious  people  fuppofe  to  confift  of  the 
fpirits  of  the  departed,  are  phenomena  of  this  nature,  which  we 
fliall  fpeak  of  when  we  come  to  treat  of  phofphorus. 


CHAPIIlR  II. 

Concerning  Oxigenous  Gas,  or  Vital  Air. 

THIS  gafeous  fubftance  was  difcovered  by  the  celebrated 
Prieftly,  on  the  fir  ft  of  Auguft  1774*  Since  that  memorable 
day,  means  have  been  devifed  of  obtaining  it  from  various  fub- 
flances  ;  and  its  properties  have  (hown  that  it  is  a  production 
of  the  mod  interelting  nature  in  the  knowledge  of  chemiftry. 
'  No  part  of  the  atmofphere  exhibits  vital  air  in  its  greateft  de- 
gree of  purity.  It  is  always  combined,  mixed,  or  altered  by 
other  fubftances. 

But  this  air,  which  is  the  mofl  general  agent  in  the  operations 
of  nature,  exifts  in  combination  with  various  fubftances  ;  and 
it  is  by  their  decompofition  that  it  maybe  extracted  and  procured, 
.  A  metal  expofed  to  the  air  becomes  changed :  and  thefe  chang- 
es are  produced  only  by  the  combination  of  the  pure  air  with 
the  metal  itfelf.  Simple  diftillation  of  fome  of  thefe  metals 
thus  changed,  or  oxides,  is  fufficient  to  difengage  this  vital  air  ; 
and  it  is  then  obtained  in  a  verv  pure  Hate,  by  receiving  it  in  the 
hydro-pneumatick  apparatus.  One  ounce  of  red  precipitate  af- 
fords about  a  pint. 

All  acids  have  vital  air  for  their  bafe ;  there  are  fome  which 
jield  it  eafiiy.  The  diftillation  of  nitre  decompofes  the  nitrick 
acid  ;  and  about  twelve  hundred  cubick  inches  of  oxigenous  gas 
are  obtained  from  a  pound  of  this  fait. 

The  nitrick  acid  when  diftilled  from  various  fubftances,  is  de- 
ccmpofed,  and  its  conftituent  parts  maybe  obtained  feparately. 

Meflrs.  Prieftly,  In^enhoufz,  and  Sennebier  difcovered  near- 
ly at  the  f<ime  time,  that  vegetables  expofed  to  the  light  of  the 
fun  emit  vital  air.  We  (hall  ehev^^here  fpeak  of  the  circum- 
ftances  of  this  phenomena  ;  but  fhall  at  prefent  confine  our- 
f^lves  to  the  obferv^tion,  that  the  emifiion  of  vital  air  is  propor- 
tioned to  the  rigour  of  the  plant,  and  the  vivacity  of  the  light ; 
and  that  the  direcl  emifiion  of  the  rays  of  the  fun  is  not  necef- 
fary  to  produce  this  gafeous  dew  j  it  is  fulficient  that  the  plant 
be  well  enlightened,  in  order  that  it  may  tranfpire  pure  air  ; 
for  I  have  often  collet  led  it  in  abundance  from  a   kind  of  mofs 


fftal  Air'.  ^J 

licH  covers  the  bottom  of  a  veflel   filled  with   water,   and  fo 

11  defended  that  the  fun  never  (hone  directly  upon  it. 

In  order  to  procure  the  vital  air  which  is  difengaged  from 
plants,  it  is  fufficient  to  enclofe  them  beneath  a  glafs  veflel  fil- 
hd  with  water,  and  inverted  over  a  tiib  filled  with  the  fame  flu- 
id. The  moment  the  plant  is  aded  on  by  the  fun,  fmall  bub- 
bles of  air  are  formed  on  its  leaves,  which  detaching  themfelves, 
rife  to  the  upper  part  of  the  veflel,  and  difplace  the  liquid. 
.  This  dew  of  vital  air  is  a  beneficial  gift  of  nature,  to  repait 
inceflantly  the  confumption  of  vital  air.  The  plant  abforbs  at- 
mofpherical  mephitis,  and  emits  vital  air.  Man,  on  the  con- 
trary, is  kept  alive  by  vital  air,  and  emits  much  mephitis.  It 
appears  therefore  that  the  animal  and  vegetable  kingdomslaboiir 
for  each  other  •,  and  that  by  this  adnriirjlble  reciprocity  of  fer- 
vice  the  atmofphere  is  continually  repairfcdj  and  an  equilibrium 
is  maintained  between  its  conftituent  principles. 

The  influence  of  folar  light  is  not  confined  to  the  produ£lion 
of  vital  air  by  ifs  action  upon  vegetables  alone  ;  it  has  likewife 
the  Angular  property  of  deconhpofing  certain  fubftances,  and 
difcngaging  this  gas. 

A  bottle  of  dxigenated  muriatick  acid,  expofed  to  the  fun; 
fuffers  all  the  fuperabundant  oxigene  which  it  contained  to  ef- 
cape,  and  pafl'es  to  the  ftate  of  ordinary  muriatick  acid.  The 
fame  acid,  expofed  to  the  fun  in  a  bottle  wrapped  in  black  pa- 
{5er,  does  not  fufi'er  any  change  ;  and,  when  heated  in  a  dark 
place,  is  even  reducible  into  gas  without  decompofition.  The 
Tiitrick  acid  likewife  aflbrds  bxigenods  gas,  when  expofed  to  the 
fun  ;  whereas  heat  alcne  volatilises  it  without  decompofition.. 

The  muriate,  or  marine  fait  of  filver,  placed  underwater,  and 
<*xpofed  to  the  fun,  fuflTers  oxigenous  gas  to  efcape  from  it.  I 
have  obferved  that  red  precipitate  likewife  affords  oxigene  in 
fimilar  cafes,  and  that  it  becomes  black  in  no  very  long  Ipace  of 
time. 

We  may  likewife  obtain  oxigenous  gas  by  difengaging  it  fromi 
its  bafis  by  means  of  the  fulphurick  acid.  The  procefs  to  which 
i  give  the  prefefence,  on  account  of  its  fimplicity,  is  the  follow- 
iiig  : — I  take  a  fmall  apothecary's  phial,  info  which  1  put  one 
or  two  ounces  of  manganefe,  and  pour  thereon  a  fuflicient  quan- 
tity of  fulphurick  acid  to  form  a  liquid  pafle.  I  afterwards  fit 
a  cork  to  the  opening  of  the  bottlcji  with  a  hole  through  it,  into 
which  is  inferted  a  recurved  tube  ;  one  of  whofe  extremities 
enters  the  bottle,  while  the  otlier  is  placed  under  the  (lielf  of  the 
pneumato-chemical  apparatus.  When  the  apparatus  is  thusf 
difpofed,  I  prefent  a  fmall  coal  to  the  lower  part  of  the  bottle, 
a'!?d  oxigenous  gas  is  immediately  difengaged. 
N 


^S  Vital  Air, 

Xhe  manganefe  I  ufe  was  difcovered  by  me  at  St.  Jean  d'c 
Gardonnenque.  It  affords  its  oxigene  with  fuch  facility,  that 
nothing  more  is  neceflary  for  this  purpofe  than  to  incorporate  it 
with  the  fulphurick  acid.  This -gas  is  not  perceptibly  mixed' 
with  nitrigenous  gas  (or  phlogifticated  air)  ;  and  the  firft  bub- 
ble is  as  pure  as  the  laft. 

Oxigenous  gas  exhibits^  certain  properties,  according  to  its  de^ 
gree  or  purity.  Thefe  depend  in  general  upon  the  fubftances? 
which  afford  it.  That  which  is  obtained  from  the  mercurial 
oxides  almoft  always  holds  a  fmall  quantity  of  mercury  in  folu- 
tion  :  I  have  been  a  witnefs  to  its  having  produced  a  fpeedy  fal- 
jvation  on  two  perfons  who  ufed  it  fordiforders  of  the  lungs. 
In  confequence  of  thefe  obfervations,  I  filled  bottles  with  this 
gas,  expofed  them  to  an  intenfe  cold,  and  the  fides  became  ob- 
fcured  with  a  ftratum  of  mercurial  oxide,  iii  a  ftate  of  extreme 
divifion.  I  have  feveral  times  heated  the  bath,  over  which  I 
caufed  this  gas  to  pafs  *,  and  I  obtained  at  two  different  times 
a  yellow  precipitate  in  the  bottle  in  which  f  had  received  the  gas. 

The  oxigenous  gas  extra£led  from  plants  is  not  equally  pure 
with  that  afforded  by  the  metallick  oxides :  but  from  whatever 
fubftances  it  is  obtained,  its  general  properties  are  the  following. 

A.  It  is  more  ponderous  than  the  air  of  the  atmofphere  ;  the 
cubick  foot  of  atmofpherical  air  weighing  feven  hundred  and 
twenty  grains,  while  the  cubick  foot  of  pure  air  weighs  {twtn 
hundred  and  fixty^-five.  According  to  Mr.  iCirwan,  its  weight 
is  to  that  of  common  air  as  eleven  hundred  and  thfee  to  one 
thoufand.  One  hundred  and  fixteen  inches  of  this  air  weighed 
39,09  grains  ;  one  hundred  and  fixieen. inches  of  common  air 
weighed  35>38  grains  at  the  temperature  of  ten  degrees  of  Reau- 
mur, and  twenty.eight  inches  of  preffure.  One  hundred  parts 
of  common  air  weighed  forty-fix,  and  one  hundred  parts  of  vital 
air  fifty. 

B.  Oxigenous  gas  \s  the  only  fluid  proper  for  combuftion. 
This  acknowledged  truth  caufed  the  celebrated  Scheele  to  give 
it  the  name  of  Air  of  Fire. 

To  proceed  with  greater  order  in  the  examination  of  one  of 
the  moft  important  properties  of  oxigenous  gas,  fince  it  belongs 
exclufively  to  this  fluid,  we  (hall  lay  dbwn  the  four  following 
principles,  as  inconteftible  refults  of  all  the  known  fa<^s. 

The  firR  principle. — Combuftion  never  takes  place  without 
vital  air. 

The  fecond  principle. — In  every  combuftion  there  is  an  ab* 
forption  of  vital  air. 

The  third  principle. — ^There  is  an  augmentation  of  weight  in 
the  prodiift  5  of  combuftion  equul  to  the  weight  of  the  vital  air 
abforbed. 


VkaJ  Air.  99 

The  fourHi  principle. — In  all  combuflion  there  Is  a  difengage- 
iTicnt  of  heat  and  light. 

I.  The  firft  of  thefe  propofitions  is  a  drift  truth.  Hydrogen- 
ous gas  does  not  burn  alone,  without  the  affiftance  of  oxigene  ; 
and  all  combuflion  ceafes  the  moment  that  cxigenous  gas  is 
wanting. 

II.  The  fecond  principle  contains  a  truth  no  lefs  general. 
|f  certain  bodies,  fuch  as  phofphorus,  fulphur,  &c.  be  burned 
in  very  pure  oxigenous  gas,  this  is  ahforbed  to  the  laft  particle,; 
and  when  the  combuflion  is  efFecled  in  a  ^mixture  of  feveral 
gafes,  the  oxigene  alone  is  abforbed,  an4  vthe  others  remain  un- 
changed. 

In  the  flower  comhuftions,  fiich  as  the  rancidity  of  oils,  and 
vthe  oxidations  of  metals,  there  is  equally  an  abforption  of  oxi- 
gene, as  may  be  (hewn  by  confining  thefe  bodies  in  a  determi- 
4iate  mafs  of  air. 

III.  The  third  principle,  though  not  lefs  true  than  the  preced- 
ing, requires  more  explanation  ;  and  for  this  purpofe  we  fhall 
diftinguifli  thofe  combufUons  whofe  refult,  refidue,  and  pro- 
duct are  fixed,  from  thofe  Vv'hich  afford  volatile  and  fugacious 
fubftances.  In  the  firfl  cafe  the  oxigenuous  gas  quietly  com- 
bines with  the  body  ;  and  by  weighing  the  fame  body  the 
moment  the  combuflion  has  completely  taken  place,  it  is  ealily 
afcertained  whether  the  increafe  in  weight  be  proportioned  to 
the  oxigene  abforbed.  This  happens  in  all  the  cafes  wherein 
the  metals  are  oxided,  or  oils  rendered  rancid  ;  and  in  the  pro- 
du6lion  of  certain  acids,  fuch  as  phofphprick,  thcfulphurick,&c. 
Jn  the  fecond  cafe,  it  is  more  diflicult  to  weigh  all  the  refults  of 
.the  combuflion,  and  confequently  to  ^certain  whether  the  aug- 
mentation in  weight  be  proportioned  to  the  quantity  of  the  air 
abforbed.  Neverthelefs,  if  the  combuflion  be  made  in  inver- 
ted vefTels,  and  the  whole  of  the  produds  be  collecled,  it  is 
found  that  their  aiigmentation  in  weight  is  llri £11  y  equal  to  that 
of  the  air  abforbed. 

IV.  The  fourth  principle  is  th^  whofe  applications  are  the 
mofl  interefling  to  be  known. 

In  mofl  combuflions,  the  oxigenous  gas  h^omes  fixed  and 
concrete.  It  therefore  abandons  the  calorick  which  maintain- 
ed it  in  the  aeriform  ilate  i  and  this  calorick  being  fet  at  liber- 
ty produces  heat,  and  endeavours  to  combine  itfelf  with  the 
fubftances  nearefl  at  hand. 

The  difengagement  of  heat  is  therefore  a  .conftant  efFe£l  in 
all  the  cafes  wherein  vital  air  is  fixed  in  bodies  ;  and  it  follows, 
from  this  principle — i.  That  heat  is  mod  eminently  refident 
ii^ithe  oxigenous  gas  which   maintains  combuflion.     2.  Tliat 


TfOO  ,  ^tal  Air. 

the  more  oxigene  is  abforbed  in  a  given  time,  the  ftrongcr  will 
be  tliQ  heat.  3.  That  the  only  method  of  producing  a  violent 
i^eat  confifts  in  burning  bodies,  in  the  pureft  air.  4.  That  fire 
and  heat  mufl  be  more  intenfe  in  proportion  as  the  air  is  more 
condenfed.  5.  That  currents  of  air  are  neceilary  to  maintain 
and  expedite  combuftion.  It  is  upon  this  principle  that  the 
theory  of  the  efFecfts  of  the  cylinder  lamps  is  founded  :  the  cur- 
rent of  air  which  is  renewed  through  the  tube,  fupplies  frefh 
air  every  inftant  ;  and  by  continually  applying  a  new  quantity 
of  oxigenous  gas  to  the  flame,  a  heat  is  produced  fufficient  to 
ignite  and  deftroy  the  fmoke. 

It  is  likewife  on  the  fame  principle  that  we  explain  the  great 
diflTerence  that  exifts  between  heat  produced  by  a  flow-  combuf- 
tion, and  that  which  is  afforded  by  rapid  combuftion.  In  the 
latter  cafe  the  fame  quantity  of  heat  and  light  is  produced  in  2^ 
fecond,  which  might  have  been  produced  in  the  other  cafe  in  a 
much  longer  time. 

The  phenomena  of  combuftion,  by  means  of  oxigenous  gas^ 
depend  likewife  upon  the  fame  laws.  ProfeiTor  Lichtenberger^ 
of  Gottingen,  foldered  the  blade  of  a  knife  to  a  watch  fpring  by 
means  of  oxigenous  gas  ;  Meflirs.  Lavoifier  and  Erhmann  have 
fubje«fied  almoft  all  the  known  bodies  to  the  a£lion  of  fire 
maintained  by  oxigenous  gas  alone  ;  and  they  produce  effecls 
which  the  burning-glafs  could  not  have  operated. 

Mr.  Ingenhoufz  has  (hewn  us  that  if  an  iron  wire  be  bent  into 
a  fpiral  form,  and  any  combuftible  fubftance  whatever  be  fixed 
to  one  of  its  ends,  and  fet  on  fire,  the  wire  will  itfelf  be  fufed 
by  plunging  it  into  oxigenous  gas. 

Mr.  Forfter,  of  Gottingen,  found  that  the  light  of  glow- 
worms is  fo  beautiful  and  bright  in  oxigenous  gas  that  one 
fingle  infe6l  was  fufficient  to  afford  light  to  read  the  Anonces 
Savantes  of  Gottingen,  printed  in  a  very  fmall  chara6l:er. 
Nothing  more  is  wanting  therefore  than  to  apply  this  air  to 
combuftion  with  facility  and  economy  ;  and  Mr.  Muef^ 
nier  has  fucceeded  in  this,  by  conftrufling  a  fimple  and  com- 
modious apparatus.  On  this  fubjed  the  treatife  of  Mr.  Erh- 
mann on  fufion  may  be  confulted. 

The  defcription  of  the  gazometer  may  likewife  be  feen  in 
the  Elementary  Treatife  of  Chemiftry,  by  Mr.  Liavoifier. 

We  fhall  diftinguifh  three  fta'tes  in  the  very  adt  of  combufr 
tion — ignition,  inflammation,  and  detonation. 

Ignition  takes  place  when  the  combuftible  body  is  not  in  the 
aeriform  ftate,  nor  fufceptible  of  affuming  that  ftate  by  the  fimr 
pie  heat  of  combuftion.  This  happens  when  well-made  chaj4 
«p4l  is  burne4# 


Vital  Air,  if  | 

When  the  combufllble  body  is  prefented  to  oxigcnous  gas, 
tn  the  form  of  vapour  or  gas,  the  refult  is  flame  ;  and  the  flame 
is  more  confiderable,  in  proportion  as  the  combuftible  body  is 
inore  volatile.  The  flame  of  a  candie  is  not  kept  up  but  by  the 
volatilization  of  the  wax,  which  is  continually  efi^e^ted  by  the 
heat  of  the  combuflion. 

Detonation  is  a  fpeedy  and  rapid  inflammation,  which  occa- 
(ions  a  noife  by  the  inftantaneous  formation  of  a  vacuum. 
Mofl  detonations  are  produced  by  the  mixture  of  hydrogenous 
and  oxigenous  gas,  as  I  have  (hev/n  in  my  Memoir  upon  Deto- 
nations, in  the  year  178 1.  It  has  been  fince  proved,  that  the 
product  of  the  rapid  combullion  of  thefe  two  gafes  is  water- 
Very  ftrong  detonations  may  be  produced  by  burning  a  mixture 
of  one  part  of  oxigcnous  gas  with  two  of  hydrogene.  The  effect 
may  be  rendered  itill  more  terrible,  by  caufing  the  mixture  to 
pafs  through  foap-water,  and  fetting  fire  to  the  bubbles  which 
are  heaped  on  the  furface  of  the  fluid. 

Chemiflry  prefents  feveral  cafes  in  which  the  detonation 
arifes  from  the  fudden  formation  of  fopie  gafeous  fubftances, 
fuch  as  that  w^hich  is  produced  by  the  inflammation  of  gunpow- 
der ;  for  in  this  cafe  there  is  a  fudden  production  of  carbon  ick 
acid,  of  nitrogene  gas,  &c.  The  production  or  inftantaneous  cre- 
ation of  any  gas  whatever  mult  occafion  a  fhock  or  agitation 
in  the  atmofphere,  which  neceflarily  affords  an  explofion  ;  the 
efl^edt  of  thefe  explofions  increafes,  and  becomes  ftronger,  from 
the  oppofition  of  any  obftacles  againft  the  efcape  of  the  gas. 

C.  Oxigcnous  gas  is  the  only  gas  proper  for  refpiration.  It 
is  the  moft  eminent  property  which  has  entitled  it  to  the  name 
of  Vital  Air  ;  and  we  (hall  give  the  preference  to  this  denom- 
ination in  the  prefent  article. 

It  has  long  fince  been  known  that  animals  cannot  live  without 
the  afliftance  of  air.  But  the  phenomena  of  refpiration  have 
been  very  imperfettly  known  until  lately. 

Of  all  the  authors  who  have  written  concerning  refpiration, 
the  ancients  are  thofe  who  have  had  the  moft  accurate  ideas  of 
it.  They  admitted  in  the  air  a  principle  proper  to  nourifh  and 
fupport  life,  which  they  denoted  by  the  name  q{ pabulum  vita  s 
and  Hippocrates  exprefsly  fays,  fpiritus  ettatn  alimenium  efl» 
This  idea,  whicli  was  connected  with  no  hypothefis,  has  been 
fucceflTively  replaced  by  fyftcms  void  of  all  foundation.  Some- 
times the  air  has  been  confidered  as  a  ftimulus  in  the  lungs, 
which  kept  up  the  circulation  by  its  continual  a£tion.  Vide 
Haller.-— Sometimes  the  lungs  have  been  confidered  as  bellows 
defigned  to  ccol  the  body,  heated  ^^y  a  thoi|fand  "imaginary 
caules  ;  and  when  it  was   proved  that   the  volume  of  air  was 


iOZ  Vital  jiir, 

'diminiflied  in  the  lungs,  it  was  thought  to  be  an  explanation  c^ 
every  difficulty,  to  fay  that  the  air  was  deprived  of  its  fpring. 

At  this  day,  however,  we  are  enabled  to  throw  feme  light  on 
one  of  the  moft  important  fun(Slions  of  the  human  body.  In 
order  to  proceed  with  more  perfpicuity,  we  ftiall  reduce  our 
notions  to  feveral  principles. 

1 .  No  animal  can  live  without  the  ^ffiftance  of  air.  This  fadl 
is  univerfally  admitted  j  but  it  has  not  been  known  until  lately 
that  the  facuhy  which  the  air  pofleifes,  of  anfwering  the  pur- 
pofe  of  refpiration,  arifes  only  from  one  of  the  principles  of 
atmofpherick  air,  known  by  the  name  of  vital  air. 

2.  All  animals  do  not  require  the  fame  purity  in  the  air. 
Birds,  as  well  as  men,  and  the  greateft  part  of  quadrupeds,  re- 
quire a  very  pure  air  ;  but  thofe  which  live  in  the  earth,  or 
which  hide  themfelves  in  ^  flate  of  ilupefaQion  during  the 
winter,  can  fubfift  by  nieans  of  a  lefs  pure  air. 

3.  The  manner  of  refpiring  the  air  is  different  in  the  feveral 
fubjeds.  In  general,  nature  has  given  to  animals  an  organ, 
which  by  its  involuntary  dilation  and  contraction  receives  and 
and  expels  the  fluid  in  which  the  animal  moves  and  exifts. 
This  organ  is  more  or  lefs  perfedl:,  more  or  lefs  concealed  and 
defended  from  external  injury,  according  to  its  importance, 
and  influence  upon  the  life  of  the  cyeature,  as  IMr.  Brouflbnnet 
has  obferved. 

Amphibious  animals  refpire  by  means  of  lungs  :  but  they 
can  fufpend  their  motion  even  whilft  they  are  in  the  air  ;  as  I 
have  obferved  with  regard  to  frogs,  which  flop  their  refpiratiou 
at  pleafure. 

The  manner  of  refpiration  in  fifhes  is  rery  different ;  thefe 
animals  come  from  time  to  time  to  inhale  the  air  at  the  furface 
of  the  water,  where  they  fill  their  veficle,  ajnd  digeft  it  after- 
wards at  their  eafe.  I  have  for  a  long  time  obferved  the  pher 
nomena  of  fifties  in  the  adl  of  refpiration  ;  and  am  well  afTur- 
€d  that  they  are  fenfible  of  the  aftion  of  all  the  gafes,  like 
other  animals.  Mr.  De  Fourcroy  has  obferved  that  the  air 
contained  in  the  veficle  of  the  carp  is  nitrogene  gas  (phlogifli- 
cated  air.) 

Infe61:s  with  trachess  exhibit  organs  flill  more  remote  from 
purs  in  their  conftrudlion.  In  thefe  animals,  refpiration  is  ef- 
fected by  the  tracheae  diflributed  along  the  body.  They  ac-? 
-company  all  the  veffels,  and  terminate  by  lofing  themfelves  in 
infenfible  pores  at  the  furface  of  the  ikin. 

Thefe  infe£ls  appear  to  me  to  exhibit  feveral  very  evident 
points  of  anabgy  with  vegetables. 


Vital  AiK 


10^ 


I.  Their  refplratory  organs  are  formed  in  the  fame  manner^ 
being  difpofed  through  the  whole  body  of  the  vegetable  and  the 
animal. — 2.  Infeds  do  not  require  a  great  degree  of  purity  in 
the  air  ;  and  plants  are  nourifhed  with  atmofpherical  mephi- 
fis. — 3.  Both  the  one  and  the  other  tranfpire  vital  air.  The 
abbe  Fontana  difcovered  fevetal  infe6ls  in  ftagnant  waters, 
which  when  expofed  to  the  fun  aiibrded  vital  air  ;  and  the 
green  matter  which  is  formed  in  ftagnant  waters,  and  is  by  Dr. 
Prieftley  placed  among  the  confervas,  in  conformity  with  the 
opinion  of  his  friend  Mr.  Bewley — which  Mr.  Senebier  has 
fuppofed  to  be  the  conferva  cefpitofa  filis  re5lis  undique  divergefiti* 
bus  Halleriy  and  which  has  appeared  to  Dr.  Ingenhoufz  to  be 
nothing  elfe  btrt  a  mafs  of  animalcula — affords  a  prodigious 
quantity  of  this  air  when  expofed  to  the  fun. — -4.  Infetls  like- 
wife  afford,  by  chemical  analyffs,  principles  fimilar  to  thofe  of 
plants,  fuch  as  refins,  volatile  oils,  &c. 

Father  Vaniere  appears  to  have  known,  and  very  elegantly 
cxprefTed,  the  property:  of  vegetables  to  fupport  themfelvcs  by 
means  of  vital  air  : 

....  Arbor  cnin  (res  non  ignofa),  ferarum 
hifUr  ct  halituum,  pifcifque  latentis  in  imo 
Ourgite,  vitaks  et  rcddit  ct  accipit  auras 

PROEDIUM  RuSTItUM,   i.    vL 

Animals  with  lungs  refpire  only  by  virtue  of  the  vital  air 
which  furrounds  them.  Any  gas  deprived  of  this  mixture  be- 
comes immediately  improj^er  for  refpiration  ;  and  this  fundlion 
ts  exercifed  with  fo  much  the  greater  liberty  as  vital  air  exifta 
in  a  greater  proportion  in  the   air  refpired. 

Count  Morozzo  placed  fuccefTively  feveral  full-grown  fpar- 
rows  under  a  glafs  betl,  inverted  over  water.  It  was  at  firft 
filled  with  atmofpherical  air,  and  afterwards  with  vital  air. 
He  obferved — 

I.  In  atmofpherical  air,  Hoars.    Min. 

The  firft  fparrow  lived       3  o 

Thefecond         --03 
The  third         -         -         o  i 

The  water  rofe  in  the  vefTel  eight  lines  during  the  life  of  the 
firft  ;  four  during  the  life  of  the  fecond  •,  and  the  third  pro-' 
duced  no  abforpiion. 


*04  fllaf  At?* 


a.  In  vital  air 

Hours. 

M?n : 

Tlie  fird  fparrow  lived 

5 

23" 

The  fecond 

. 

2 

lO 

The  third 

. 

I 

30 

The  fourth 

. 

I 

10 

The  fifth 

« 

6 

3^ 

The  fixth 

. 

o 

47. 

The  feventh 

. 

o 

27 

The  eighth 

« 

0 

3^ 

The  ninth 

^ 

o 

22 

The  tenth 

- 

o 

21 

From  thefe  experiments  it  may  be  concluded,  i.  That  an  an- 
Jmal  lives  longer  in  vital  air  than  in  atmofpherical  air.  2. 
That  an  animal  can  live  in  air  in  which  another  has  died.  3, 
That,  indeperrdent  of  the  nature  of  the  air,  refpecl  mull  be  had 
to  the  conftitution  of  the  animals,  as  the  fixth  lived  forty-feverf 
minutes,  and  the  fifth  only  thirty.  4.  That  there  is  either  an 
abforpt?cn  cf  air,  or  the  prodiiftion  df  a  ntew  kind  of  air,  vt^hicb 
is  abforbcd  by  the  water  as  it  rifes. 

j^t  remains,  at  prefent,  to  examine  what  are  the  changes  pro- 
duced by  refpiration.  i.  In  the  air.  2.  In  the  blood. 

The  gas  emitted  by  expiration  is  a  mixture  of  nitrogene  gas, 
carbonick  acid,  and  vital  air.  If  the  air  which  iflues  front  the 
lungs  be  made  to  p?ffs  through  lime-water,  it  renders  it  turbid  ; 
if  it  be  received  through  tincture  of  turnfole,  it  reddens  it ;  and 
if  a  pure  alkali  be  (Libftituted  inftead  of  the  tin6lure  of  turn- 
fole, it  becomes  efFervefcent. 

When  the  carbonick  acid  has  been  abforbed  by  the  foregoing 
procefs,  the  remainder  of  this  air  confids  of  nitrogene  gas  and* 
vital  air.  The  vital  air  is  (hown  to  be  prefent  by  means  of  ni- 
trous air.  The  air  in  which  I  had  caufed  five  fparrows  to  per- 
iPo,  afForded  feventean  hundredth  parts  of  vital  air.  After  hav- 
ing thiis  deprived  the  expired  air  of  all  its  vital  air,  and  all  if) 
carbonick  acid^  the  remainder  is  nitrogene  gas. 

It  has  been  obferved  that  frugivorous  animals  vitiate  the  air 
Icf'^  than  carnivorous  animals. 

A  portion  of  the  air  is  abforbcd  in  refpiration.  Borelli  for- 
merly took  notice  of  this  ;  and  Dr.  Jurin  had  calculated  that 
a  man  infpired  forty  cubick  inches  of  air  in  his  ufual  inhalations, 
and  that  in  the  greatefi;  he  could  receive  tv/o  hundred  and  twen- 
ty inches  •,  but  that  a  portion  was  always  abforbed.  The 
cslebvated  Dr  H?.les  endeavoured  to  determine  this  abforption 
more  dricily,  and  he  ellimated  it  at  a  fixry-eighth  of  the  totaF 
of  the  respired  air  •,  but  he  did  not  conHder  it  as  more  than  a 
bimdrcd  wA  thirtv-rixthyon  account  of  crrours  which  he  fuppo- 


Vital  Air.  IC5 

fed  to  have  taken  place.  Now  a  man  refpircs  twenty  times  in  a 
minute,  and  inhales  forty  cubicle  inches  of  air  at  each  infpira- 
tion  :  this  makes  forty-eight  thoufand  per  hour  •,  which,  divid- 
bd  by  one  hundred  and  thirty-fix,  gives  about  three  hundred  and 
fifty-three  inches  of  air  abforbed  and  deftroyed  in  the  hour.  The 
procefs  of  Hales  is  not  exaft  ;  becaufe  he  palTed  the  air  expired 

I   through  water,  which  muft  have  retained  a  fenfible  proportion. 

j       From  more  accurate  experiments,  Mr.   Dc  la    Metherie  has 

I  proved,  that  three  hundred  and  fixty  cubick  inches  of  vital  air  ate 

;  abforbed  in  an  hour. 

My  experiments  have  not  fhbwn  near  fo  great  a  lofs. 

This  fa£l  affords  a  proof  of  the  facility  with  which  air  Is  vltl- 

'  ated  by  refpiration  when  it  is  not  renewed,  and  {hows  why  the 
air  of  theatres  is  in  general  fo  unwholefome. 

II.  The  firfl:  efFedl:  which  the  air  appears  to  produce  upon  the 
blood  is,  that  of  giving  it  a  vermilllon  colour.  If  the  blackilh 
venous  blood  be  expofed  in  a  pure  atmofphere,  it  becomes  of  a 
vermillion-colour  at  its  furface  :  this  fa(^t  is  daily  obferved  whea 
blood  is  fuffered  to  remain  expofed  in  a  porringeV  to  the  air- 
Air  which  has  remained  in  contatt  with  blood  extinguifhes  can- 
dles, and  precipitates  lime-water.  Air  injedted  into  a  de- 
terminate portion  of  a  vein  between  two  ligatures,  renders  the 
blood  of  a  higher  colour,  according  to  the  fine  experiments  of 
Dr.  Hew  fan. 

...     The  blood  which  returns  from  the  lungs  is  of  a  higher  colour, 

•*  according  to  the  obfervations  of  Meflrs.  Cigna,  Hewfon,  5jc. 
Hence  arifes  the  great  intenfity  of  the  colour  of  arterial  blood, 
compared  with  venous  blood. 

Mr.  Thouvenel  has  proved,  that  by  withdrawing  the  air 
which  is  in  contact  with  the  bloody  it  may  be  again  made  to  lofe 
its  colour. 

Mr.  Beccaria  expofed  blood  in  a  Vacuum,  where  it  remained 
black,  but  aflumed  the  moft  beautiful  vermillion  colour  as  foon 
as  it  was  again  expofed  to  the  air.  Mr.  Gigna  covered  blood 
with  oil,  and  it  preferved  its  black  colour. 

Dr.  Piieftly  caufed  the  blood  of  a  flieep  to  pafs  fucceflively 
into  vital  air,  common  air,  mephitick  air,  &c.  and  he  found 
that  the  blackeft  parts  aflumed  a  red  colour  in  refpirable  air, 
and  that  the  intenfity  of  this  colour  was  in  proportion  to  the 
quantity  of  vital  air  prefcnt.  The  fame  philofopher  filled  a 
bladder  with  blood,  and  expofed  it  to  pure  air.  That  portion  of 
blood  wliich  touched  the  furface  of  the  bladder,  became  red, 
while  the  internal  part  remained  black  ;  an  abforption  of  air 
therefore  took  place  through  the  bladder,  in  the  fame  manncras 
when  the  contail:!  is  immediate, 
O 


lo6  Pltal  Air, 

All  tliefe  fa^ts  inconteftibly  prove,  that  the  vermilHon  colou/ 
aflumed  by  the  blood  in  the  lungs,  is  owing  to  the  pure  air 
which  combines  with  it. 

The  Vermillion  colour  of  blood  is  therefore  the  firft  efFetffc  of 
the  conta£l,  abforption,  and  combination  of  pure  air  with  the 
blood. 

The  fecond  eiredl  of  refpiration  is  to  eftablifh  a  real  focus  of 
heat  in  the  lungs  5  which  is  a  circumflance  very  oppofite  to  the 
precarious  and  ridiculous  notion  of  thofe  who  have  confidered 
the  lungs  as  a  kind  of  bellows  defigned  to  cool  the  human  body. 

Two  celebrated  phyficians,  Hales  and  Boerhaave,  have  ob- 
ferved  that  the  blood  acquired  heat  in  pailing  through  the  lungs ; 
and  modern  phyfiologifts  have  eftimated  this  augmentation  of 
heat  at  eleven  hundredths. 

The  heat  in  each  clafs  of  individual  animals  is  proportioned 
to  the  magnitude  of  their  lungs,  according  to  Meflrs.  De  BufFon 
and  Brouflbnet. 

Animals  with  cold  blood  have  only  one  auricle  and  one  ven- 
tricle, as  Ariftotle  obferved. 

Perfons  who  have  refpired  vital  air,  agree  in  afErming  that 
they  have  perceived  a  gentle  heat  vivifying  the  lungs,  and  infen- 
fibly  extending  from  the  breafc  into  all  the  other  parts  of  tlie 
body. 

Ancient  and  modern  fa£ls  unite  therefore  to  prove,  that  ;. 
fociis  of  heat  really  exifts  in  the  lungs,  and  that  it  is  maintained 
and  kept  up  by  the  air  of  refpiration.  We  are  able,  at  prefent, 
to  explain  all  thefe  phenomena.  In  fafb  there  is  an  abforption 
of  vital  air  in  refpiration.  Refpiration  then  may  be  confidered 
as  an  operation  by  means  of  which  vital  air  paiTes  continually 
from  the  gafeous  to  the  concrete  ftate  :  it  muft  therefore  at  each 
inftant  abandon  the  heat  which  held  it  in  folution,  and  in  the 
llateofgas.  This  heat  produced  at  every  infpiration  muft  be 
proportioned  to  the  volume  of  the  lungs,  to  the  activity  of  this 
organ,  to  the  purity  of  the  air,  the  rapidity  of  the  infpirations, 
&c.  Hence  it  follows  that,  during  the  winter,  the  heat  produc- 
ed muft  be  more  confiderable,  becaufe  the  air  is  more  conden fed, 
and  exl;iibits  more  vital  air  under  the  fame  volume.  By  the  fame 
reafon,  refpiration  ought  to  produce  more  heat  in  the  inhabit- 
ants of  northern  climates  •,  and  this  is  one  of  the  caufes  prepar- 
ed by  nature  to  temperate,  and  continually  balance,  the  extreme 
cold  of  thefe  climates.  It  follows  likevi^ife  that  the  lUngs  of  afth- 
matick  perfons  are  lefs  capable  of  digefting  the  air ;  and  1  am  af- 
fured  that  they  emit  the  air  without  vitiating  it :  from  which  caufe 
their  complexion  is  cold,  and  their  lungs  continually  languilh- 
ing  5.   vital   air  is  therefore  wonderfully  comfortable  to  them. 


Vital  Air.,  107 

it  may  be  eafily  conceived  from  jihefe  principles  v^h'J  the  heat 
of  animals  is  proportioned  to  the  volume  of  their  lungs  ;  and 
why  thofe  vi^hich  have  only  one  auricle,  and  one  ventricle,  have 
cold  blood,  &c. 

The  phenomena  of  refpiration  are  therefore  the  fame  as  thofe 
of  combuftion. 

Vital  air,  by  combining  with  the  blood,  forms  the  carbonick 
acid,  which  may  be  confidered  as  antiputrefcent  as  long  as  it  re- 
mains in  the  circulation  ;  and  that  it  is  afterwards  emitted 
through  the  pores  of  the  fkin,  according  to  the  experiments  of 
the  count  De  Milly,  and  the  obfervations  of  Mr.  Foquet. 

Vital  air  has  been  ufed  with  fuccefs  in  certain  diforders  of  the 
human  body.  The  obfervations  of  Mr.  Caillens  are  well  known. 
|Ie  caufed  perfons  afreded  with  phthifical  diforders  to  refpire 
it  with  the  greateft  fuccefs.  I  have  myfelf  been  a  witnefs  to 
the  moft  wonderful  effe6i:s  of  this  air  in  a  fimilar  cafe.  Mr. 
X)e  B was  in  the  l^fl  (lage  of  a  confirmed  phthifis.  Ex- 
treme weaknefs,  profufe  fweats,  a  flux  of  the  belly,  and  in  (liort 
every  fymptom  announced  the  approach  of  death.     One  of  my 

friends,  Mr.  De  P ,  put  him  on  a  courfe  of  vital  air.     The 

patient  refpired  it  with  delight,  and  alked  for  it  with  all  the  ea- 
gernefs  of  an  infant  at  the  bread.  During  the  time  that  he  ref- 
pired it  he  felt  a  comfortable  heat,  which  diftributed  itfelf 
through  all  his  limbs.  His  ftrength  increafed  with  the  greateft 
rapidity ;  and  in  fix  weeks  he  was  able  to  take  long  walks.- 
This  ftate  of  health  laftedfor  fix  months  :  but  after  this  interval 
he  relapfed  ;  and  being  no  longer  able  to  have  recourfe  to  the 

ufe  of  vital  air,  becaufe  Mr.  De  P had  departed  for  Paris> 

he  died. — I  am.  very  far  from  being  of  opinion  that  the  refpiration 
of  vital  air  ought  to  be  confidered  as  a  fpecifick,  in  cafes  of  this 
nature.  I  am  even  in  doubt  wliether  this  powerful  air  is  per- 
fectly adapted  to  fuch  circumftances  ;  but  it  infpires  cheerful- 
nefs  renders  the  patient  happy,  and  in  defperate  cafes  it  is  moft 
certainly  a  precious  remedy,  which  can  fpread  flowers  on 
the  borders  of  the  tomb,  and  prepare  us  in  the  gentleft  manner 
for  the  laft  dreadful  effort  of  nature. 

The  abfolute  neceffity  of  vital  air  in  refpiration,  enables  us 
to  lay  down  pofitiye  principles  for  purifying  the  corrupted  air 
of  any  given  place.  This  may  be  done  in  three  ways.  The 
iirft  confifts  in  correcling  the  vitiated  air  by  means  of  fubftances 
which  are  capable  of  feizing  the  noxious  principles.  The  fecond 
confifts  in  difplacing  the  corrupted  air,  and  fublHtuting  frefli  air 
in  the  rooni  of  it ;  as  is  done  by  means  of  ventilators,  the  agita- 
tion of  doors,  Uc.  And  the  third  confifts  in  pouring  into  the 
mephitifed  atmofphere  a  new  quantity  of  vital  air. 


ro8  Nitrogene    Gas. 

The  proccfTes  employed  in  purifying  corrupted  air,  are  not  all 
certain  in  their  efFefls  The  fires  which  are  lighted  for  this  pur- 
pofe  have  no  other  advantage  than  to  eftablilh  afcending  cur- 
rents, and  to  burn  unhealthy  exhalations  *,  and  perfumes  do 
nothing  more  than  difguife  the  bad  fmell,  without  changing  the 
nature  of  the  air,  as  the  experiments  of  Mr.  Achard  fliew. 


CHAPTER  III. 

Concerning  Nitrogene  Gas^  Azote^  or  Atmofpherical  Mephitis. 

IT  has  been  long  fince  afcertained,  that  air  which  has  ferved 
the  purpofesof  combuftion  and  refpiration,  is  no  longer  proper 
for  thofe  ufes  :  the  air  thus  corrupted  has  been  diflinguilhcd  by 
the  names  of  phlogifticated  Air,  Mephi:tifed  Air,  Atmofpherical 
Mephitis,  &c.  I  call  it  Nitrogene  Gas,  for  the  reafons  explained 
in  the  preliminary  difcourfe. 

But  this  refidiic  of  combuftion  or  refpiration  is  always  mixed 
v/ith  a  fmall  quantity  of  vital  air  and  carbonick  acid,  which  must 
be  removed  in  order  to  have  the  nitrogene  gas,  in  a  ftate  of 
purity.  There  are  feveral  methods  which  may  be  ufed  to  obtain 
nitrogene  gas,  in  a  very  pure  flate. 

I.  Scheelehas  taught  us,  that  by  expofing  fulphure  of  alkali 
or  liver  of  fulphur,  in  a  veiTel  filled  with  atmofpherical  air,  the 
vital  air  is  abforbed  ;  and,  when  the  abforption  is  complete,  the 
nitrogene  gas  remains  pure. 

By  expoiing,  in  atmofpherick  air  over  mercury,  a  mixture  of 
iron  and  fulphur,  kneaded  together  with  water,  Mr.  Kirwan  ob- 
tained nitrogene  gas  lo  pure,  that  it  fuffered  no  dimiinution  by 
nitrous  gas.  He  deprived  it  of  all  humidity,  by  fuccellively  in- 
troducing dried  blotting-paper  into  the  vefl'el  which  contained  it. 
Care  mufl  be  taken  to  withdraw  this  air  in  time  from  the  pafle 
which  affords  it  ;  otherwife  it  will  be  mixed  with  hydrogenc 
or  inflammable  gas,  which  is  afterwards  difengaged.  2.  When 
by  any  means,  fuch  as  the  oxidation  of  metals,  the  rancidity  of 
oils,  the  combuftion  of  phofphorus,  &c.  the  vital  air  of  the  at- 
mofphere  is  abforbed,  the  refidue  is  nitrogene  gas.  All  thefe 
proccfTes  afford  methods  of  greater  or  lefs  accuracy  to  determine 
the  proportions  of  vital  air  and  nitrogene  gas  in  the  compofitioii 
of  the  atmofphere. 

3.  This  mephitis  may  like  wife  be  procured  by  treating  muf- 
cular  flefh,  or  the  well  wafhed  fibrous  part  of  blood,  with  ni- 
trick  acid  in  the  hydro-pneumatick  apparatus.     But  It   muft  be 


AtiKofpherich  Aw,  109 

.arefuUy  obferved  that  thefe  animal  matters  ought  to  be  frefh  5 
:or,  if  they  have  bef^un  to  be  changed  by  the  putrid  fermenta- 
tion, they  afford  carbonick  acid  mixed  with  hydrogene  gas. 

A.  This  gas  is  improper  for  refpiration  and  combuftion. 

13.  Plants  live  in  ihit>  air,  'and  freely  vegetate  in  it. 

C.  This  gas  mixes  with  the  other  airs,  without  combining 
with  them. 

D.  It  is  lighter  than  the  atmofpherick  air,  the  barometer 
Handing  at  30.46,    and  Fahrenheit's  therr/iometer  at  60:  the 

weight  of  nitrogene  gas  is  to  that  of  common  air  as  nine  hun- 
dred and  eighty-dve  to  one  thoufand. 

E.  Mixed  with  vital  air,  in  the  proportion  of  72  to  28,  It 
conftitutes  our  atmofphere. '  The  other  principles  which  anal- 
yfis  exhibits  in  the  atmofphere,  are  only  accidental,  ;ind  by  no 
ineans  neceflary. 


SECTION    VI. 

Concerning  the  mixture  of  Kitrogene  and  Oxigene  Gas  ;  or  of  Atmol^ 
pherick  Air. 

X  HE  gafeous  fubftances  we  have  treated  of  feldom 
cxift  alone  and  infulated  ;  nature  prefents  them  every  where 
to  our  obfervation  in  a  ftate  of  mixture  or  of  combination.  In 
the  firft  cafe  thefe  gafes  preferve  the  aeriform  ftate  ;  in  the 
fecond  they  for  the  mofl  part  form  fixed  and  folid  bodies.  Na- 
ture, in  its  feveral  decompofitions,  reduces  almoft  the  princi- 
ples of  bodies  into  gas.  Thfefe  new  fubftances  unite  together, 
combine,  and  from  thence  refult  compounds  of  confiderablc 
fimplicity  in  their  principles,  but  which  become  complicated 
by  fubfcquent  mixtures  and  combinations.  We  may  follow 
the  operations  of  nature,  ftep  by  ftep,  without  departing  from 
the  plan  we  have  adopted. 

The  mixture  of  about  feventy-two  parts  of  nitrogene  gas,  and 
twenty-eight  of  oxigene,  form  this  fluid  mafs  in  which  we 
live.  Thefe  two  principles  are  fo  well  mixed,  and  each  of  them 
is  fo  neceflary  to  the  fupport  of  the  various  fun(flions  of  individu- 
als which  live  or  vegetate  upon  the  globe,  that  they  have  not  yet 
been  found    feparate  and  alone. 

The  proportion  of  thefe  two  gafes  is  fubjecfl  to  variation  in 
the  mixture  v.'hich  forms  the  atmofphere  ;  but  this  diflerence 
depends  only  upon  local  caufes  ;  and  the  moft  ufual  propor- 
jon  i§  that  which  we  have  here  mentioned. 


rio  AUncfphericl   Air, 

The  charaiSleriflick  properties  of  vital  air  are  modified  by 
thofe  of  nitrogene  gas,  and  thefe  modifications  even  feem  to 
be  neceffhry  :  for  if  we  were  to  refpire  vital  air  in  its  flate  of 
purity  it  would  quickly  confume  our  life  ;  and  this  virgin  air  is 
no  more  fuitable  to  our  exiftence  than  dillilled  water.  Nature 
does  not  appear  to  have  defigned  us  for  the  ufe  of  thefe  prin- 
ciples in  their  greateil  degree  of    perfe£l:ion. 

The  atmofpherick  air  is  elevated  feveral  leagues  above  our 
heads,  and  fills  the  deepeft  fubterraneous  cavities.  It  is  in- 
vifible,  in fip id,  inodorous,  ponderous,  elaftick,  &c.  It  was  the 
only  gafeous  fubftance  known  before  the  prefent  epocha  of 
chemiilry  ;  and  the  infinite  gradations  of  all  the  inyifible  fluids 
which  prefent ed  themfeives  fo  frequently  to  the  obfervation 
of  philofophers,  were  always  attributed  to  modifications  of  the 
air.  Almcft  the  whole  of  what  has  been  written  upon  the  air 
relates  only  to  its  phyfical  properties.  We  fhall  confine  our- 
felyes  to  point  out  the  chief  of  thefe. 

A.  Air  is  a  fluid  of  extreme  rarefa£lion,  obedient  to  the 
fmalleft  motion  ;  the  flighteft  percufiion  deranges  it  ;  and  its 
equilibrium,  which  is  continually  deftroyed,  lis  continually  en- 
deavouring to  reflore  itfelf. 

Though  very  fluid,  it  pafl^es  with  difficulty  through  orifices 
by  means  of  which  groflTer  liquids  can  eafily  penetrate.  This 
has  caufed  philofophers  to  fuppofe  that  its  parts  were  o|  a 
branched  form.* 

B.  The  atmofpherick  air  is  invifible.  It  refradls  the  rays  of 
l4ght  without  refle£ling  them  :  for  it  is  without  fufficient  proofs 
that  fome  philolbphers  have  imagined  that  large  malTes  of  this 
fluid  are  of  a  blue  colour. 

It  appears  that  the  air  is  inodorous  itfelf  \  though  it  is  the 
vehicle  of  odorant  particles. 

It  may  be  confidered  as  infipid  ;  and  when  its  contacl  afi^ecfts 
us  varioufly,  we  ought  to  attribute  it  to  its  phyfical  qualities. 

C.  It  was  not  until  the  middle  of  the  laft  century  that  its 
weight  was  afcertained  by  accurate  experiments.  The  impof- 
fibility  of  fupporting  water  in  a  tube  open  at  the  bottom,  to  a 
greater  height  than  thirty-two  feet,  caufed  Torriceliius  to  fuf- 
pe£l  that  an  external  caufe  fupported  the  liquid  at  that  height, 
and  that  it  was  not  the  horrour  of  a  vacuum  which  precipitated 
the  water  iti  the  barrels  of  pumps.  This  celebrated  philofopher 
filled  a  tube  clofed  at  one  of  its   extremities  with  mercury  :  he 

*  This  is  a  deception.  It  is  true  that  the  cnhefivc  attraction  renders  it^ 
difficult  to  dilplace  any  dcr.fc  fluid  (rom  a  Capillary  tube  hy  the  intrulioH  of 
air  ;  but  every  expcrinicrkC  ot  the  air  puinp,  tiie  ct^ndeufor,  and  the  barom- 
ctiT,  fliows  with  vvhat  laciliiy  the  air  pafTes  throu<jh  the  iniHlIcfl  orifices.  T. 


Gtneral  Properties  of  Water.  ifx 

vivcrfcci  this  into  a  vefTcl  filled  with  the  fame  metal ;  and  obferv- 
cd  that  the  mercury,  after  feveral  ofcillations,  conftantly  fubfid- 
ed  to  the  height  of  twenty-eight  inches.  He  immediately  faw 
that  the  difference  of  elevations  correfponded  with  the  relative 
weights  of  thefe  two  fluids,  which  are  in  the  proportion  of  four- 
teen to  one.  The  immortal  Pafchal  proved,  fome  time  after- 
wards, that  liquids  were  fupported  at  this  elevation  by  a  column 
of  atmofpherical  air  ;  and  he  afcertained  that  their  height  va- 
ries according  to  the  length  of  the  column  which  preifes  upon 
them. 

D.  The  elafticity  of  the  air  is  one  of  the  properties  upon  which 
natural  philofophers  have  made  the  greateft  number  of  experi- 
ments ;  and  it  has  even  been  applied  to  confiderable  advantage 
in  the  art$. 


SECTION     VII. 


'oncerning  the  Corabination  of  Oxigenous  Ga?  and  Hydrogene,  which 
forms    Water. 


W  AT£R  has  been  long  confidered  as  an  elementary 
principle  ;  and  when  accurate  experiments  had  compelled  chem- 
ifts  to  clafs  it  among  compound  ^fubilances  ;  a  refiltance  and 
oppofition  vt^ere  made  to  it,  which  were  not  manifefted  when 
the  air,  the  earth,  and  the  other  matters  reputed  to  be  elementa- 
-ry,  were  fubje<n:ed  to  fimilar  revolutions.  It  feems  to  me  how- 
ever, that  this  analyfis  is  equally  ftridl  with  that  of  air.  Water 
is  decompofed  by  feveral  proceiTes  ;  it  is  formed  by  the  com- 
bination of  oxigene  and  hydrogene  :  and  we  find  that  a!l  the 
phenomena  of  nature  and  art  confpire  to  prove  the  fame  truth. 
What  more  can  be  required  to  aftbrd  an  abfolute  certainty  re- 
fpecfling  any  phyficai  facb  ? 

Water  is  contained  in  bodies  in  a  greater  or  lefs  quantity,  and 
may  be  confidered  in  two  dates  :  it  is  either  in  the  flatc  of  [im^ 
pie  mixture,  or  in  a  Itate  of  combination.  In  the  iirll  cafe,  it 
tenders  bodies  humid,  is  perceptible  to  the  eye,  and  may  be  dif- 
cngaged  with  the  grcateft  facility.  In  the  fecond,  it  exhibits 
no  chara£ler  which  rtiows  that  it  '  is  in  a  ftate  of  mixture.  It 
exilts  in  this  form  in  cryftals,  falts,  plants,  animals,  tzc.  It  is 
this  water  which  the  celebrated  Bernard  has  called  Generative 
Water;  and  of  which  he  has  made  a  fifth  element,  to  diflin- 
guifli  it  from  exhahtive  water. 


i  1 2  General  Properties  of  tVater, 

"Water,  exifting  in  a  (late  of  comolnation  in  bodies,  concufS 
in  imparting  to  them  hardnefs  and  tranfparency.  Salts,  and 
moft  ftony  cryltals,  lofe  their  tranfparency  when  they  are  de- 
prived of  their  water  of  cryftallization. 

Some  bodies  are  indebted  to  water  for  their  fixity.  The  acids, 
for  example,  acquire  fixity  only  by  combining  with  water. 

Under  thefe  various  points  of  view,  water  may  be  confider- 
ed  as  the  general  ce^-nent  of  nature.  The  Hones  and  falts 
\vhich  are  deprived  of  it,  become  pulverulent ;  and  water  fa- 
cilitates the  coagulation,  re-union,  and  confidence  of  the  parti- 
cles of  Hones,  falts,  &c.  as  we  fhall  fee  in  the  operations  per- 
formed with  plafters,  lutes,  mortar,  &c. 

Water,  when  difengaged  from  its  combinations,  arid  in  a 
Hate  of  abfolute  liberty,  is  one  of  the  mod  confiderable  agents 
in  the  operatiojis  of  this  globe.  It  bears  a  part  in  the  forma- 
tion and  decompofition  of  all  the  bodies  of  the  mineral  king- 
dom :  it  is  necefl'ary  to  vegetation,  and  to  the  free  exercife  of 
molt  of  the  fun£lions  of  animal  bodies  ;  and  it  hallens  and 
facilitates  the  deftruc^ion  of  thefe  bodies  as  foon  as  they  are 
deprived  of  the  principle  of  life. 

For  a  certain  time  water  was  thought  to  be  a  fluid  earth. 
The  diflillation,  trituration,  and  putrefadlion  of  water,  which 
always  left  an  earthy  refidue,  afforded  credit  to  an  opinion 
that  it  was  converted  into  earth.  On  this  fubje£t,  the  works 
of  Wallerius  and  MargrafFmay  be  confulted  :  but  Mr.  Lavoi- 
fier  has  Ihewn  that  this  earth  arifes  from  the  wear  of  the  vef- 
fels  i  and  the  celebrated  Scheele  has  proved  the  identity  of  the 
nature  of  this  earth  with  that  of  the  glafs  vellels  in  which  the 
operations  were  made.  So  that  the  opinions  of  the  philofoph- 
ical  world  are  at  prefent  decided  in  this  refpetf. 

In  order  to  obtain  accurate  ideas  of  a  fubllance  fo  neceffary 
to  be  known,  we  will  confider  water  under  its  three  different 
Hates,  of  folidity,  fluidity,  and  gas. 


ARTICLE     L 

Concerning  Water  in  the  State  of  Ice. 

Ice  Is  llie  natural  ftate  of  water  whenever  it  is  deprived  of  a 
portion  or  that  calorick  with  which  it  is  combined  when  it  ap- 
pears in  the  form  of  a  liquid  or  gas. 

The  converfion  into  ice  is  attended  with  feveral  phenomena 
which  fcidom  vary. 

A.  The  firlc  of  all,  and  at  the  fame  time  the  mod  extraor- 
diiurv,  ij  af^nliblc  nrodui^Vion  cf  hcHt  at  the  moment  in  which 


Water  in  the  Solid  State, 


•J  5^3 


t  pafe Jtd  t'he  folld  (late.  The  experiments  of  Meflrs. 
hrenheit,  Triewald,  Baume,  De  Ratte,  leave  no  doubt  on  this 
>je£l  ;  io  that  the  water  is  colder  at  the  inftant  of  congela- 
.'1  than  the  ice  itfelf. 

A  flight  agitation  of  the  fluid  facilitates  its  converfion  into  ice 
arly  in  the  fame  manner  as  the  flighted  motion  very  fre- 
quently determines  the  cryftallization  of  certain  falts.  This 
arifes,  perhaps,  from  the  circumftance,  that  by  this  means  the 
calorick,  v/hich  is  interpofed  between,  the  particles,  and  may 
'^npofe  itfelf  to  the  produ<Slion  of  the  phenomena,  may  be  ex- 
jlled  or  difcngaged.  In  proof  of  this  opinion,  it  is  feen  that 
tiie  thermon:.eter  rifes  at  the  very  fame  inftant,  according  to 
Fahrenheit. 

B.  Frozen  water  occupies  a  larger  fpace  than  fluid  water  : 
^eare  indebted  to  the  Academy  del  Cimento  for  the  proofs  of 
this  truth.  In  their  experiments,  bomb  Ihells,  and  the  ftrong- 
t{\  veflels,  being  filled  with  water,  Vere  burft  into  pieces  by 
the  congelation  of  this  fluid.  The  trunks  of  trees  are  fplit 
and  divided  with  a  loud  noife,  as  foon  as  the  fap  freezes  ;  and 
'folikewife  ftones  are  broken  in  pieces  the  moment  the  water 
with  which  they  are  impregnated  pafl~es  to  the  ftafe  of   ice. 

C.  Ice  appears  to  be  nothing  more  than  a  confufed  cryftal- 
lization. Mr.  De  Mairan  obferved  that  the  needle-formed 
cryftals  of  ice  unite  in  an  angle  of  either  fixty  or  one  hundred 
and  twenty  degrees. 

i  Mr.  Pelleticr  obferved,  in  a  piece  of  fiftulous  ice,  cryftals  ia 
the  form  of  flattened  triangular  prifms,  terminated  by  two  di- 
hedral fummits. 

Mr.  Sage  obferves,  that  if  a  piece  of  ice,  which  contains 
■water  in  its  internal  parts,  be  broken,  the  water  runs  out, 
and  the  internal  cavity  is  found  to  be  lined  with  beautiful 
tetrahedral  prifms,  terminated  in  four-fided  prifms.  Thefe 
prifms  are  often  articulated  and  crofl^ed.  Vide  M.  Sage,  Anales 
de  Chimie,  tom.  i.  p.  77. 

Mr.  Macquart  has  obferved,  that  when  it  fnows  at  Mofcow, 
and  the  atmofphere  is  not  too  dry,  the  air  is  obferved  to  be 
loaded  with  beautiful  cryftallizations  regularly  flattened  and 
as  thin  as  a  leaf  of  paper.  They  confift  of  an  union  of  fibre* 
which  (lioot  from  the  fame  centre  to  form  fix  principal  rays  ; 
and  thefc  rays  divide  themfelves  into  fmall  blades  extremely 
brilliant  :  he  obferved  feveral  of  thefe  flattened  radii  which 
were  ten  lines  in   diameter. 

I).  WJ.ien  water  pafles  from  the  folid  to  the  liquid  ftate,  it 
produces  cold  by  the  abforption  of  a  portion  of  heat,  as  is  con- 
firmed by  the  fine   experiments  of  Wilcke.     This  produ(^ion 


%t 


tlif'  Water  in  the  Liquid  Slate, 

of  cold  by  the  fufion  of  ice,  is  likewife  proved  by  the  pi'.u  . 
of  the  confectioners,  who  fufe  certain  fiilts  with  ice,  in  order  U. 
produce  a  degree  of  cold  below  o. 

Ice  is  found  in  many  places  in  'great  mafics,  known  by  the 
name  of  Glacieres  :  certain  mountains  arc  conftantly  covered 
with  them,  and  the  foutliern  ocean  abounds  with  them.  The 
ice  formed  by  fait  water  affords  frefti  water  when  melted  ;  and 
in  feveral  northern  provinces  water  is  faid  to  be  concentrated 
by  froft,  to  collet^  the  fait  in  holes  in  folution.  1  have  likewife 
obferved,  that  feveral  metallick  falts  are  precipitated  by  exoofin^ 
their  folutions  to  a  temperature  fufficient  to  freeze  them/  The^^ 
ite  which  was  formed  did  not  poffefs  the  characlers  of  the  fak 
which  had  been  diilolved. 

Hail  and  fnow  are  nothing  but  modifications  of  ice.  We 
may  confider  hail  as  produced  by  the  fudden  difengagement  of 
the  elaftick  fluid,  which  concurs  in  rendering  water  liquid  :  it 
is  almoft  always  accompanied  with  thunder.  The  experiments 
of  Mr.  Quinquet  have  confirmed  this  theory. — I  will  here  re« 
late  a  fa61:  to  which  I  myfelf  waswitnefe,  at  Montpelier,  and  of 
which  philofophers  may  advantageouily  avail  themfelves.  On 
the  29th  of  October,  1786,  four  inches  of  water  idl  at  Montpe- 
lier ;  a  violent  explofion  of  thunder,  which  was  heard  about 
four  in  the  evening.,  and  which  appeared  to  be  very  near,  cauf- 
ed  a  mod  dreadful  fnower  of  hail.  At  this  inftant  a  druggift, 
who  was  employed  in  his  cellar  in  preventing  the  mifchief  oc- 
cafioned  by  the  filtration  of  water  through  the  wall,  was  highly 
aftoniflied  to  behold  that  the  water  which  came  through  the  wafj 
was  inftantly  changed  into  ice.  He  called  in  feveral  neighbours 
to  partake  of  his  furprize.  I-  vifited  the  place  a  quarter  of  an 
hour  afterwards  and  found  tea  pounds  of  ice  at  the  foot  of  the 
wall ;  I  was  well  affurcd  that  it  could  not  have  paffed  through 
the  wall,  which  did  not  exhibit  any  crack,  but  appeared  to  be  in 
very  good  condition.  Did  the  Hime  caufe,  which  determined 
the' formation  of  hail  in  the  atmofphere,  zO:  equally  in  this  cel- 
lar ^ — I  relate  the  fa£l  only,  and  forbear  to  make  any  conjecture 
wpon  it. 

ARTICLE  IT. 

Concerning  Water  in  the  Liquid  State. 

The  natural  ftate  of  water  appears  to  be  that  of  ice  :  b«t  ib 
mofl:  ufual  ftate  is  that  of  fluidity  ;  and  under  this  form  it  pof- 
fefles  certain  general  properties  which  we  fhall  proceed  to  dc- 
fcribc. 


DifliUatkn  of  Water,  ,.;  '        1 15 

The   experiments  of  the  Academy  del  Cimento  have  caufed 

le  philofophical  word  to  deny  the  lead  elafticity  to  water,  be- 
.aufe  it  efcapcd  through  the  pores  of  bails  of  metal  ftrongly  com- 
prefTed,  rather  than  yield  to  preflure.  But  MefiVs.  Zimmerman, 
^nd  the  abbe  Mongez,  have  endeavoured  to  pKove  its  elasticity 
from  the  very  experiments  upon  which  the  contrary  opinion  has 
been  built*. 

The  liquid  (late  renders  the  force  of  aggregation  in  water  lefs 
powerful,  and  it  enters  into  combination  more  readily  in  this 
form.  Water  which  flows  on  the  furface  of  our  globe  is  never 
pure.  Rain-water  is  feldom  exempt  from  fome  mixture,  asap- 
pears  from  the  fine  fcries  of  experiments  of  the  celebrated  Mar- 
graff.  I  have  afcertained  at  Montpelier,  that  rain-water  in 
ilorms  is  more  impure  than  that  of  a  gentle  ihower — that  the 
water  which  falls  firft  is  lefs  pure  than  that  which  falls  after 
feveral  hours  or  feveral  days  rain — that  the  water  v/hich  falls 
when  the  wind  blov/s  from  the  fea  to  the  fouthward,  contains 
fea-falt  •,  whereas  that  which  is  produced  by  a  northerly  wind, 
does  not  contain  a  particle. 

Hippocrates  has  made  feveral  very  important  obfervations  re- 
fpe6:ing  the  various  qualities  of  water,  relative  to  the  nature  of 
the  foil,  the  temperature  of  the  climate,  &c. 

As  it  is  of  iniportance  to  the  chemift  to  have  very  pure  water 
for  feveral  delicate  operations,  it  is  neceflary  to  point  out  the 
means  which  may  be  ufed  to- carry  any  water  whatever  to  this 
<legree  of  purity. 

Water  is  purified  by  diftillation.  This  operation  is  perform- 
ed in  veflels  called  Alembicks.  The  Alembick  is  compofed  of 
two  pieces  ;  a  boiler  or  cucurbit,  and  a  covering,  called  the  capi- 
tal or  head. 

The  water  is  put  into  the  cucurbit,  from  which  it  is  raifed  m 
.vapours  by  means  of  fire,  and  thefe  vapours  are  condenfed  by 
cooling  the  head  with  cold  water.  The  condenfed  vapours  flow 
:into  a  veflel  defigned  to  receive  them.  This  is  called  Diltilled 
Water  ;  and  is  pure,  becaufe  it  has  left  behind  it  in  the  cucur- 
bit the  falts  and  other  fixed  principles  which  altered  its   purity. 

Diftillation  is  more  fpeedy  and  quick,  in  preportlon  as  the 
.prefliire  of  the  air  is  lefs  upon  the  furface  of  ihz  ftagnant  fluid. 

*  The  experiments  of  Canton,  to  prove  the  comprtfllbility  of  water  are 
well  known,  and  may  be  fccn  in  the  Philofophical  Tranfaclions.  Ke  iuciofed 
water  in  Ipherical  glals  velltls,  from  which  a  narrow  neck  proceeded  like  that 
•  of  a  thermometer  :  the  water  was  found  to  occupy  a  largoir  fpace  when  the 
.prefTure  of  the  atmofphere  was  removed  iiy  the  air-pump,  and  a  Icli  fpacc 
v/hen  a  greater  prcflarc  was  added  l>y  tMc  condeufor.    T. 


Il6         •  jD'rflillat ton  of  Water, 

Mr.  Lavoifier  diftilled  mercury  in  vacuo  ;  and  the  abbe 
has  made  a  happy  application  of  thefe  principles  to  d  ill  illation- 
It  is  to  this  fame  principle  that  we  mult  refer  the  obfervations 
of  alnioft  all  naturalifts  and  philofophers,  who  have  remarked 
that  the  ebullition  in  the  liquid  becomes  more  eafy,  in  proportioru 
:as  we  afcend  a  mountain  from  any  other  elevation  :  and  it  is  in 
conlequence  of  theie  principles,  that  Mr.  Achard  conftrutfed 
an  inltrument  to  determine  the  heights  of  mountains,  by  the 
degrees  of  temperature  of  the  ebullition  of  boiling  water. 

The  abbe  Mongez,  and  Mr.  Lamanow,  obferved  that  ether 
evaporates  with  prodigious  facility  upon  the  peak  of  TenerifFe  y 
and  Mr.  De  SaulTure  has  confirmed  thefe  experiments  on  the 
mountains  of  Switzerland. 

A  true  dillillation  is  carried  on  every  where  at  the  furface  of 
our  globe.  The  heat  of  the  fun  raifes  water  in  the  form  of  va- 
pours \  tliefe  remain  a  certain  time  in  the  atmofphere,  and  af~ 
wards  fall  in  the  form  of  dew,  by  (imple  refrigeration.  This  rife 
and  fall  of  humidity,  which  fucceed  each  other,  wafh  and  purge 
the  atmofphere  of  all  thofe  particles,  which  by  their  corruption 
or  deveiopement  might  render  it  intedlious  ;  and  it  is  perhaps 
this  combination  of  various  miafmata  with  water  which  renders 
the  evening  dew  fo  unvvholefome. 

It  is  to  a  (imilar  natural  dillillation  that  we  ought  to  refer  the 
alternate  tranfition  of  water  from  the  liquid  ftate  to  that  of  va- 
pour, which  forms  clouds,  and  by  this  means  conveys  the  water 
Irom  the  fea  to  the  fummits  of  mountains,  from  which  it  is 
precipitated  in  torrents,  to,  return  agam  to  the  common  recepta- 
cle. 

We  find  traces  of  tlie  dillillation  of  water  in  the  mofl  remote 
5iges.  The  firft  navigators  in  the  illands  of  the  Archipelago  fill- 
ed their  pots  with  fait  water,  and  received  the  vapour  in  fpunges 
placed  over  them.  The  procefs  of  diiUlling  the  water  of  the 
lea  has  been  fucceffively  brought  to  perfection  ;  and  Mr  Poif- 
fonnier,  has  exhibited  a  very  well  conllru6ted  apparatus  to  pro- 
cure freih  wat(;r  at  all  times  in  abundance. 

Pure  water  requires  to  be  agitated,  and  combined  with  the 
air  of  the  atmofphere,  to  render  it  wholefome.  Hence,  no 
doubt  it  is,  that  water  immediately  produced  by  melting  fnow, 
is  unlit  to  drink. 

T'he  charaders  of  potable  water  are  the  following  : 

1.  A  lively,  freih,  and  agreeable  tafte. 

2.  The  property  of  boiling  readily,  and  alfo  that  of  boilin^^' 
peafe  and  other  puife. 

3.  The  virtue'  of  dilTolving  foa.p  without  curdling. 


Jfait^r  in  the  State  of  Gas.  1 1 ) 


AllTlCLE     III. 

Concerning  Water  in    tlie  State  of  Gas 

Many  fubftances  are  naturally  in  the  flate  of  an  aeriform 
fluid,  at  the  degree  of  the  temperature  of  our  atmofphere  ;  fuch, 
for  example,  are  the  carbonick  acid ;  and  the  oxigenous,  the 
hydrogenous,  and  the  nfitrogenous  gales. 

Other  fubftances  evaporate  at  a  degree  of  heat  very  near  that 
in  which  we  live.  Ether  and  alcohol  are  in  this  fituation. 
The  firft  of  thefe  liquors  palTes  to  the  ftate  of  gas  at  the  tem- 
perature of  35  degrees  5  the  fecond  at  that  of  80  (of  Reaumur). 

Some  fluids  require  a  flronger  heat  for  this  purpofe  5  fuch 
as  water,  the  fulphurick  and  nitrick  acids,  oil,  &c. 

To  convert  water  into  an  aeriform  fluid,  MeiTrs.De  la  Place  and 
Lavoifier  filled  a  glafs  veflel  with  mercury,  and  reverfcd  it  over 
a  diih  filled  with  the  fame  metal.  Two  ounces  of  water  were 
transferred  beneath  this  veflel ;  and  the  mercury  was  heated 
to  the  temperature  of  between  ninety-five  and  a  hundred  of 
Reaumur,  by  plunging  it  in  a  boiler  filled  with  the  mother 
water  of  nitre.  The  included  water  became  rarefied,  arnl  oc- 
cupied the  whole  capacity. 

Water  by  paflTmg  through  earthen  veflels  ignited  in  the  fire 
becomes  converted  into  gas,  according  to  Prieltley  and  Kirwan. 
The  ieolipile,  the  fteam-engine,  the  digefter  of  Papin,  and  the 
procefs  of  the  glafs-blowers,  who  blow  large  globes  by  injecting 
a  mouthful  of  water  through  their  iron  tiibe,  prove  the  con- 
verfion  of  water  into  gas. 

It  follows  from  theie  principles,  that  the  volatiHzation  of  wa- 
ter being  nothing  more  than  a  direcl  combination  of  calorick 
with  this  liquid,  the  portions  of  which  are  the  moft  immediate- 
ly expofcd  to  heat,  muft  be  the  firft  volatilized  :  and  this  is 
daily  obfcrved  j  for  it  is  continually  feen  that  ebullition  begins  at 
the  part  moft  heated.  But  when  the  heat  is  applied  equally  at 
all  parts,  the  ebullition  is  general. 

Several  phenomena  have  led  us  to  believe  that  water  may  be 
converted  into  air.  The  procefs  of  the  glafs-blowers  to  blow 
large  fpheres  ;  the  hydraulick  organ  of  father  Kircher  j  the 
phenomena  of  the  ceoiipile  ;  the  experiments  of  Meflxs.  Pricft- 
Icy  and  Kirwan  ;  the  manner  ofafhfting  combuftion,  by  fprinkv 
ling  a  fmall  quantity  of  water  upon  the  coals — all  thefe  circum- 
ftances  appeared  to  announce  the  converfion  of  water  into  air. 
But  it  was  far  from  being  fuppofed  that  moft  of  thefe  phe- 
nouiena  were  produced  by  the  decompofition  of  this  fluid  ;  and 


*  '^        *M'"  Compofttion  of  Water, 

the  genius  of  Mr.  Lavoifier  was  neceflary  to  carry  this  point  <; 
<io£lrine  lo  the  degree  of  certainty  and  precifion,  which  in  m*, 
opinion  it  now  appears  to  poffefs. 

Meffrs.  Macquer  and  Dc  la  Metherie  had  already  obferved, 
that  the  combultion  of  inflammable  air  produced  much  water. 
Mr.  Cavendifh  confirmed  thefe  experiments  in  England,  by  the 
Tapid  combudion  of  inflammable  air  and  vital  air.  But  Mcflrs. 
Lavoifier,  Dc  la  Place,  Monge,  and  Meufnier,  have  proved  that 
the  whole  mafs  of  the  water  might  be*  converted  into  hydro- 
gene  and  oxigene  ;  and  that  the  combuftion  of  thefe  tv/o 
_gafes  produce  a  volume  of  water  proportioned  to  the  weight  c 
the  two  principles  employed  in  this  experiment. 

1.  If  a  fmall  glafs  veiiel  be  inverted  over  mercury,  and  a 
known  quantity  of  diftilled  water  and  filings  of  iron  be  put 
into  the  upper  part  of  this  vefiTel,  inflammable  air  will  be  grad- 
ually difengaged,  the  iron  will  ruft,  and  the  water  which  moiit- 
ens  it  will  diminiih,  and  at  length  difappear  ;  the  weight'  of 
the  inflammable  air  which  is  produced,  and  the  augmentation 
in  weight  of  the  iron,  will  be  equivalent  to  the  weight  of  the 
water  made  ufe  of.  It  appears  therefore  to  be  proved,  thaf  the 
"water  is  reduced  into  two  principles,  the  one  of  which  is  in- 
flammable air,  and  the  other  is  the  principle  which  hae  enter- 
ed into  combination  with  the  metal.  Now  we  know  that  the 
oxidation  or  calcination  of  metals  is  owing  to  vital  air;  and 
consequently  tlie  two  fubfl:ances  produced,  namely,  the  vital  air 
and  inflammable  air,  arife  from  the  decompofition  of  water. 

2.  When  water  is  converted  into  the  ftate  of  vapour,  in  its 
paifage  through  an  ignited  iron  tube,  the  iron  becomes  oxided^, 
and  hydrogene  is  obtained  in  the  ftate  of  gas.  The  augmenta- 
tion of  weight  in  the  metal,  and  the' weight  of  the  hydrogene  ob- 
tained, form  precifely  a  fum  equal  to  that  of  the  v/ater  employed. 

The  experiment  made  at  Paris,  in  the  prefence  of  a  numer- 
ous commiflion  of  the  Academy,  appears  to  me  to  leave  no  fur- 
ther doubt  concerning  the  decompofition  of  water. 

A  gun-barrel  was  taken,  into  which  a  quantity  of  thick  iron 
wire,  flattened  by  hammering,  was  introduced.  The  iron  and 
the  gun-barrel  were  weighed  :  the  gun-barrel  was  then  covered 
with  a  lute  proper  to  defend  it  from  the  conta(51;  of  the  air  -,  it 
was  afterwards  placed  in  a  furnace,  and  inclined  in  fuch  a  man- 
gier as  that  water  might  run  through  it.  At  its  moft  elevated 
extremity  was  fixed  a  funnel  defigned  to  contain  water,  and  to 
let  it  pais  drop  by  drop  by  means  of  a  cock  :  this  fuimei  was 
clofed,  to  avoid  all  evaporation  of  the  water.  At  the  other  ex- 
iremity  of  the  gun-barrel  was  placed  a  tubulated  receiver,  in- 
«£ended  to  receive  the  water  which  might  pafs  without  decompo- 


Citnpojttion  cf  Water,  I  ip 

on ;  and  to  the  tubulure  of  the  receiver  the  pneumato-chem* 
xcal  apparatus  was  adapted.  For  greater  precaution,  a  vacuum 
was  made  in  the  v/hole  apparatus  before  the  operation  began. 
J^aftly,  as  foon  as  the  gun-barrel  was  red-hot,  the  water  was  in- 
troduced drop  by  drop.  IVIuch  hydrogenous  gas  was  obtained  : 
and  at  the  end  of  the  experiment  the  gun-barrel  was  found  to 
have  acquired  weight ;  and  the  fiat  pieces  of  iron  included 
within  were  converted  into  a  flratum  dP  black  oxide  of  iron,  or 
Ethiops  martial,  cryftallized  like  the  iron  ore  of  the  ifland  of  El- 
ba. It  was  afcertained  that  the  iron  was  m  the  fame  ftate  as 
that  which  is  burned  in  oxigenous  gas ;  and  the  increafed 
weight  of  the  iron,  added  to  that  of  the  hydrogene,  was  accu- 
rately equal  to  that  of  the  water  employed. 

The  hydrogenous  gas  obtained  was  burned  with  a  quantity  of 
vital  air  equal  to  that  which  had  been  retained  by  the  iron,  and 
the  fix  ounces  of  water  were  recompofed. 

3.  Meflis.  Lavoifier  and  De  la  Place,  by  burning  in  a  proper 
apparatus  a  mixture  of  fourteen  parts  of  hydrogenous  gas,  and 
eighty-fix  of  oxigene,  obtained  a  proportionate  quantity  of  water/ 
Mr.  ^Yow^^  obtained  the  fame  refult  at  Meziereaj  at  the  fame 
time.  - 

The  mod  conclufive  and  the  moft  authentick  experiment 
which  was  made  upon  the  compofition  or  fyn'thefis  of  water,  is 
that  which  was  begun  on  the  23d  of  May,  and  ended  on  the 
7th  of  June,  17S8,  at  the  Royal  Coiiege,  by  Mr.  Lefevre  de 
Gineaa. 

The  volume  of  oxigenous  gas  confumed,  when  reduced  to 
the  prefiure  of  twenty-eight  inches  of  mercury,  at  the  tempera- 
ture of  ten  degrees  of  the  thermometer  of  Reaumur,  was  35085 
(French)  cubick  inches,  and  its  weight  250  gros  10,5  grains. 

The  volume  of  hydrogenous  gas  war,  74967,4  cubick  inches, 
and  the  weight  66  gros  4,3  grains. 

The  nitrogenous  gas  and  the  carbonick  acid  which  were  rnlx« 
cd  with  thefe  gafes,  and  which  had  been  extracted  out  of  the  re- 
ceiver at  nine  feveral  times,  weighed  39,23  grains. 

The  oxigenous  gas  contained  ^^  of  its  weight  of  carbonick 
acid  ;  fo  that  the  v/eight  of  thefe  gafes  burned  was  280  gros 
63,8  grains,  which  makes  2  pounds  3  ounces  o  gros  63,8  grains. 

The  veflels  were  opened  in  the  prefence  of  the  gentlemen  of 
the  Academy  of  Sciences,  and  feveral  other  learned  men,  aad 
were  found  to  contain  2  pounds  3  ounces  o  gros  33  grains  of 
water :  this  weiglit  anfwefrs  to  that  of  the  gafes  made  ufe  of, 
wanting  3 1  grains ;  this  deficiency  may  arife  from  the  calorick 
which  held  the  gafes  in  folution  being  diflipated  when  they  be- 
came fixed,  which  muft  necefTarily  have  occafioned  a  lofs. 


120  Niti'Qgent    Gas. 

The  water  was  fabacid  to  the  tafte,  and  afforded  27I  gfaiii^ 
of  nitrick  acid,  which  acid  is  produced  by  the  combination  of 
the  nitrogene  and  oxigene  gafes. 

From  the  experiment  of  the  decompofition  of  water,  lo® 
parts  of  this  fluid  contained 

Oxigene  84,2636  =  84: 

Hydrogene       15,7364:^151 
According  to  the  experiment  of  its  compofition,    100  parts   of 
water  contained 

Oxigene  84,8  =  84^ 

Hydrogene       15,2  =  i5f 

Independent  of  thefe  experiments  of  analyfis  and  fynthefis, 
the  phenomena  exhibited  by  water,  in  its  feveral  ftates,  confirm 
our  ideas  with  regard  to  the  conftiiuent  parts  which  we  acknowl- 
edge it  to  poflefs.  The  oxidation  of  metals  in  the  interiour 
parts  of  the  earth,  at  a  diftance  from  the  atmofpherical  air,  the 
•filorefcence  of  pyrites,  and  the  formation  of  ochres,  are  phe- 
nomena which  cannot  be  explained  without  the  afliftance  of 
this  theory. 

Wat&r  being  compofed  of  two  known  principles,  mnft  aft 
like  all  other  compound  bodies  which  we  know  ;  that  is,  ac- 
cording to  the  afhnities  of  its  conflituent  parts.  It  muft  there- 
fore in  fome  inftarices  yield  its  hydrogene,  and  in  others  its  oxi- 
gene. 

If  it  be  placed  in  contaft  with  bodies  which  have  the  ftrongefl 
afTmity  with  oxigene,  fuch  as  the  metals,  oils,  charcoal,  &c.  the 
oxigenous  principle  will  unite  with  thefe  fubllances  ;  and  the 
hydrogene,  being  fet  at  liberty,  will  be  diflipated.  This  happens 
when  hydrogene  gas  is  difengaged,  by  caufing  the  acids  to  act 
upon  certain  metals  ;  or  when  red-hot  iron  is  plunged  in  water, 
as  MeiTrs.  HaiTenfratz,  Stouifz,  and  DTIellancourt  have  ob- 
ferved. 

In  vegetables,  on  the  contrary,  it  feems  that  the  hydrogene  i« 
the  principle  which  fixes  itfelf  ;  while  the  oxigene  is  eafilydif- 
engaged,  and  makes  its  efcape. 


SECTION  VIII. 

Concerning  the  Combination?  of  Nitrogene  Gac.     t.  With  Tlydrogeijc 
Gas.    a.  With  the  Earthy  principles  forming  the  Alkalis. 

It  appears  to  be  proved,  that  the  combination  of  ni- 
trogene gas  with  hydrogene  forms  one  of  the  fubflances  com- 


Vegetable  Fipied  Alkali,  12I 

prized  in  the  clafs  of  alkalis.  It  is  very  probable  that  the  others 
are  compofed  of  this  fame  gas  and  an  earthy  bafis.  It  is  frora 
thefe  confiderations  that  we  have  thought  proper  to  place  thofe 
fubftances  here :  and  we  have  adopted  that  decifion  with  fo 
much  the  more  foundation,  becaufe  the  knowledge  of  alkalis  is 
indifpenfably  necefi?.ry  to  enable  us  to  proceed  with  order  in  a 
courfe  of  chemiftry  •,  and  becaufe  thefe  re-agents  are  mod  fre- 
quently employed,  and  their  combinations  and  ufes  prefent  them- 
felvcs  at  every  ftep  in  the  phenomena  of  nature  and  art. 

It  is  an  eftablifhed  convention  to  call  every  fubftance  an  Al- 
kali,  which  is  characHierifed  by  the  following  properties  : 

A.  An  acrid,  burning,  urinous  tafte. 

B.  The  property  of  converting  fyrup  of  violets  green  ;  but 
not  the  tinclure  of  turnfole,  as  certain  authors  announce. 

C.  The  virtue  of  forming  glafs,  when  fufed  with  quartzofe 
fubftances. 

D.  The  faculty  of  rendering  oils  mifcible  with  water  ;  o£ 
cfFervefcing  with  certain  acids ;  and  of  forming  neutral  falts  with 
all  of  them. 

I  muft  obferve  that  none  of  thefe  chara£lers  is  rigorous  and 
exclufive  *,  and  that  confequently  no  one  of  them  is  fufficient 
to  afford  a  certainty  of  the  exiftence  of  an  alljali :  but  the  re- 
union of  feveral,  form,  by  their  concurrence,  a  mafs  of  proofs  or 
indications,  which  lead  us  to  fufficient  evidence. 

The  alkalis  are  divided  into  fixed  alkalis,  and  volatile  alkalis. 
This  diftincStion  is  eftablilhed  upon  the  fmell  of  thefe  fubftan- 
ces :  the  former  are  not  volatilized,  even  in  the  focus  of  the 
burning  mirror,  and  emit  no  charadleriftick  fmell-,  whereas  the 
latter  are  eafily  reduced  into  vapour,  and  emit  a  very  penetra- 
ting odour. 


CHAPTER    I. 


Concerning  Fixed  Alkalis, 

NO  more  than  two  kinds  of  fixed  alkalis  have  hitherto  been 
difcovered  :  the  one  which  is  called  Vegetable  Alkali,  pr  Pot- 
afli  j  the  other  Mineral  Alkali,  or  §oda. 


I ZZ  Vegetable  Fixed  AlkalL 

ARTICLE  I. 

GonCerriIng  the  Vegetable  Alkali,  or  Pot-Afh. 

This  alkali  may  be  extracted  from    Various   fubftances  ;  at, 
it  is  moreorlefs  pure,  according  as  it  is    afforded   by    one    fub 
ft  an  ce  or  another.     Several  varieties  are  made  in    commerce,  t< 
which  different  names  have  been  affixed  and  which  are  indifpenfi- 
bly  neceflary  to  be  known.     The  chemilt  may  indeed  confound 
all  thefe  di{tin6i;ions,   in  his  writings,  under  one  fmgle  denomi- 
ination  :  but  the  diflinQions  eltablifhed  by  the  artifts  are  found- 
ed upon  a  feries    of  experiments  which   have  proved  that  the 
virtues  of  thefe  feveral  alkalis  are  very  different  ;  and"  this  con- 
ftant  variety  in  their  eff*c6i:s  appear  to  me  to  jadify  the  various 
denominations   afligned  them. 

1.  The  alkali  extra£l:ed  from  the  lixivium  of  wood-affies,  is 
itiown  by  the  name  oi  Salin.  The /2r//«  calcined,  and  by  this  means 
difengaged  from  all  the  bl?,ckening  principles,  forms  pot-afli. 

The  affics  are  more  or  iefs  rich  in  alkali,  according  to  the  na» 
Jure  of  the  wood  which  affords  them  ,  in  general,  hard  woodr. 
contain  the  moft;  The  affies  of  beech  afford  from  ii  to  131b. 
per  quintal,  according  to  the  ertperiments  which  I  have  made 
in  the  large  vvay,  at  St.  Saveur  ;  thofe  of  box  afforded  from  12 
to  141b.  The  tables  drawn  up  by  the  feveral  adminiftrators  of 
the  gunpowder  and  faltpetre  manufadlories.  may  be  confulted, 
rerpe£ling  the  quantity  of  alkali  afforded  by  the  combuftion  of 
feveral  plants  :  they  ufed  4001b.  of  each  in  their  various  experi- 
ments 

To  extracl  tm3  alkali,  nothing  more  is  neceffary  than  to 
waili  the  aflies,  and  to  concentrate  the  diffbluticn  in  boilers  of 
caff  iron.  It  is  on  account  of  the  alkali  that  wood-affies  are 
employed  in  the  lixiviums  ufed  by  laundreffes  or  bleachers. 
The  ufe  of  alkali,  in  this  cafe,  is  to  combine  w^ith  the  fat  fub- 
ilances,  and  to  render  them  foluble  in  water. 

Almoff:  ail  the  pot-affi  fold  in  commerce  for  the  ufe  of  olt 
glafs'houfesj  our  foap-makers,  our  bleaching-grounds,  &c. 
is  fabricated  in  the  north,  v;bere  the  abundance  of  wood  admits 
t)f  its  being  applied  to  this  (Ingle  purpofe.  We  might  eftablifli 
■works  of  this  ki.td  to  fuffieicnt  advantage  in  the  foreffs  of  our 
kingdom.  But  there  is  more  to  be  done  tliun  is  generally  fup- 
pofed,  before  the  inhabitants  of  the  mountains  can  be  turned  to- 
wards this  fpecies  of  induffry.  I  have  experienced  this  difficulty 
in  the  attempts  and  very  confiderable  facrifices  which  I  have 
made,  to  fecure  this  refource  in  the  neighbourhood  of  Laigou: 


Mineral  Fixed  Aikalh 


t^:- 


nd*Lefperou.  Three  accurate  calculations  which  I  have  madea 
ive  neverthelefs  proved  that  the  pot-afli  would  coll  only  from 
^  to  1 7  livres  the  quintal,  whereas  we  purchafe  that  from  the 
)rth  at  30  or  40  livres. 

2.  The  Ices  of  wine  is  almofl  totally  converted  into  alkali  by 
-ornbuftion.  This  alkali  is  called  Ceiidres  Gravehes  :  it  has  almoii: 

Uvays  a  greenlfh  colour.     This  alkali  is  confidered  as  very  pure- 

3.  The  combuftion  of  tartar  of  wine  likewife  affords  an  aika- 
of  confiderable  purity.     It  is  ufually   burned   wrapped   up  in 

paper,  in  fmall  ^^ackets,  which  are  dipped  in  water,  and  after- 
wards expofed  upon  burning  coals.  In  order  to  purify  it,  the 
-Tefiduc  of  the  combuftion  is  difTolved  in  water,  the  foiution  con- 
^centrated  by  fire,  the  foreign  falts  feparated  in  proportion  as  they 
precipitate  ;  and  a  very  pure  alkali  is  at  laft  obtainedj  which  is 
/known  by  the  name  of  Salt  of  Tartar. 

To  procure  fait  of  tartar  more  fpecdllvs  as  well  as  more  eco- 
nomically, I  burn  a  mixture  of  equal  parts  of  nitrate  of  pot-afli 
or  common  nitre  and  tartar.  The  refidue,  after  lixiviation,  af- 
fords a  beautiful  fait  of  tartar. 

Salt  of  tartar  is  the  alkali  mod  commonly  employed  in  med- 
ical ufes  ;  it  is  given  in  the  dofe  of  feveral  grains. 

4.  If  faltpetre  be  fufed  upon  charcoal,  the  acid    is  decompo- 
sed and  difllpated,   while  the    alkali  remains  alone  and   difen- 

gaged  ;  this  is  called  Extemporaneous  Alkali. 

When  the  vegetable  alkali   has  been   brought  to  the  greateft 

Hate  of  purity,  it  attrafls  the  humidity  of  the  air,  and  is  refol- 
-ved  ino  a  liquor.  In  this  ftate  it  is  known  by  the  very  improp- 
.  cr  name  of  Oil  of  Tartar  per  Deliquium. 


ARTICLE    ri. 

Concerning  the  Mineral  Alkali,  or  Soda. 

The  Mineral  Alkali  has  been  fo  called,  becaufe  it  forms  the 
bafis  of  marine  fait. 

It  is  obtained  from   marine  plants  by  combuftion  :  for   this 
purpofe  heaps  of  the  faline  plants  are  formed  ;  and  at   the  fide 
of  thefe  heaps  a  round    cavity  is  dug,  which  is    enlarged    to- 
wards the  bottom.,  and  is  three  or  four  feet  1.1  depth  ;    this  is 
the  fire  place  in  which  the   vegetables  are   burned.     The  com- 
'  bullion  is  kept  up  without   interruption  for    feveral  days  •,  and 
•when  all  the  plants   are    confumed,  a  mafs   of  alkaline    fak  is 
found  remaining,  which  is  cut  into    pieces,  to   facilitate  its  car- 
triage  and  fale.    This  is  known  by  the  n;xiXiQ  of  Rock  Soda  or 
•Sod.:,  "  -   -       -         -.- 


i  24  Mineral  Fixed  AlkaK. 

All  marine  plants  do  not  aiFord  foda  of  the  fame  qualitf. 
The  barilla  of  Spain  affords  the  beautiful  foda  of  Alicant.  I 
am  afTured  that  we  might  cultivate  it  upon  our  coafts  in  the 
Mediterranean,  with  the  greateft  fuccefs.  This  culture  is 
highly  interefting  to  the  arts  and  commerce  ;  and  government 
ought  to  encourage  this  new  fpecies  of  induftry.  But  an  in- 
dividual, however  inclined  or  devoted  to  the  publick  good, 
might  make  vain  efforts  to  appropriate  this  commerce  to  our 
advantage,  if  he  were  not  powerfully  afTifted  by  government; 
becaufe  the  Spanifh  miniftry  has  prohibited  the  exportation  of 
the  feed  of  barilla,  under  the  ftrongeft  penalties.  In  Langue- 
doc  and  in  Provence,  we  cultivate  on  the  banks  of  our  ponds 
a  plant  known  by  the  name  of  Salicor,  which  affords  foda  of  a 
good  quality  ;  but  the  plants  which  grow  without  cultivation 
produce  an  inferiour  fort.  I  have  made  an  accurate  analyfis  of 
each  fpecies,  the  refults  of  which  may  be  feen  at  the  article 
Verrene  of  the  Encyclopedie  Methodique. 

The  mineral  alkali  is  cleared  of  all  heterogeneous  faits  by 
diffolviing  it  in  water,  and  feparating  the  feveral  falts  in  pro- 
^Dortion  as  they  fall  down.  The  laft  portion  of  the  fluid  be- 
ing concentrated  afjbrds  the  foda,  which  cryitallizes  in  rhom- 
boidal  octahedrons. 

The  mineral  alkali  is  fometimes  found  in  a  native  ftate  :  in 
Egypt  it  is  known  by  the  name  of  Natron.  The  two  lakes  of 
Natron  defcribed  bySicard  and  Mr,  Volney,  are  fituated  in  the 
defert  of  Chaiat,  or  St  Macaire,  to  the  weft  of  Delta.  Their 
bed  is  a  natural  cavity  of  three  or  four  leagues  in  length,  and 
a  quarter  of  a  league  in  breadth  j  the  bottom  is  folid  and  flony.  ^ 
It  is  dry  during  nine  months  in  the  year  ;  but  in  winter  a  wa- 
ter of  a  violet-red  colour  oozes  out  of  the  earth,  which  fills  the 
lake  to  five  or  fix  feet  in  depth  :  the  return  of  the  heat  of  fum- 
mer  evaporates  this,  and  leaves  a  bed  of  fait  behind  it  of  two 
feet  in  thicknefs,  which  is  dug  out  with  bars  of  iron.  The 
quantity  obtained  annually  amounts  to  36,000  quintals. 

Mr.  Proull:  found  natron  upon  the  fchifti  which  form  th<t 
foundation  of  the  town  of  Angers  ;  the  fame:  chemifl  likewiie 
found  it  upon  a  (lone  from  the  faltpetre  of  Paris. 

The  mineral  alkali  differs  from  the  vegetable,  becaufe — i.  It 
is  lefs  cauftick.     2.  It  is  fo  far  from  attrafting  humidity,  that 
it  efflorefces  in  the    air.     3.  It  cryftallizes  in  rhomboidal  o6la- 
hedrons.     4.  It  forms  different  producls   with  the  fame  bafc 
5.  It  is  more  proper  for  vitrification. 

Do  the  alkalis  exift  ready  formed  in  vegetables,  or  are  they 
the  product  of  the  feveral  operations  made  ufe  of  in  extracU 
ing  them  ? — This  queftion  has  divided   the  opinions  of .  chrem- 


Vegetable  Fixed  Alkali,  125 

ats.  DuHammel  and  Grofle  proved,  in  1732,  the  ejTift- 
ence  of  alkali  in  cream  of  tartar,  by  treating  it  with  the  nitrick, 
fulphurick,  and  other  acids.  MargrafF  has  given  additional 
|)roofs  of  this,  in  a  Memoir  which  forms  the  twenty-fifth  of 
his  colledion.  Rouelle  read  a  Memoir  to  the  academy  on 
the  14th  of  June,  1769,  upon  the  fame  fubjedl  :  he  even  af- 
firms that  he  was  accquainted  with  this  truth  befo^jg  the  work 
ofMargraff  appeared. — See  the  Journal  De  Phyfique,  vol.  i. 

Rouelle,  and  the  marquis  De  Bullion,  proved  tlwt  tartar 
exifts  in  muft. 

It  muft  not  be  concluded  from  the  exiftence  of  an  alkali  in 
vegetables,  that  this  fait  is  there  found  in  a  difengaged  ilate. 
On  the  contrary,  it  is  found  combined  with  acids,  oils,  &c. 

The  alkalis,  fuch  as  we  have  defcribed  them,  even  after  they 
have  been  difengaged  from  every  mixture,  by  folution,  filtration 
and  evaporation,  are  not  neverthelefs  in  that  ftate  of  purity  and 
difengagement,  which  is  necefiary  to  be  obtained  in  many  cafes : 
they  are  nearly  in  the  ftate  of  neutral  falts,  by  their  combina- 
tion with  the  carbonick  acid.  When  it  is  required  to  difen- 
gage  this  acid  the  alkaU  muft  be  diflblved  in  water,  and  quick 
Sme  then  flacked  in  the  folution.  This  fubftance  fcizes  the 
carbonick  acid  of  the  alkali,  and  gives  out  its  calorick  in  ex- 
change. We  (hall  fpeak  of  the  circumftances  of  this  operation 
when  we  (hall  have  occafion  to  treat  of  lime.  The  alkali  be- 
ing deprived  of  the  carbonick  acid,  no  longer  effervefces  with 
other  acids  ;  it  is  more  cauftick,  and  mere  violent  in  i-ts  action  j 
unites  more  eafily  to  oils  ;  and  is  then  called  Caullick  Alkali, 
Pure  Pot-afh,  or  pure  Soda. 

When  this  alkali  is  evaporated,  and  brought  into  the  dry 
form,  it  is  known  by  the  name  of  Lapis  Caulticus.  The  cor- 
rofive  virtue  of  this  fubftance  depends  principally  upon  the 
avidity  with  which  it  feizes  humidity,  and   falls  into  deliquium. 

The  cauftick  alkali,  as  it  is  ufuaily  prepared,  always  con* 
taiiis  a  fmall  quantity  of  carbonick  acid,  filiceous  earth,  iron, 
hme,  &c.  Mr.  Berthcllet  has  propofed  the  following  means  of 
purifying  it : — He  concentrates  the  cauftick  lixivium  until  it 
has  acquired  a  flight  degree  of  confiftence  ;  at  which  period 
he  mixes  it  with  alcohol,  and  draws  off  a  portion  by  diftiilation. 
Asfoonasthe  retort  is  become  cold,  he  finds  it  to  contain 
cryftals,  mixed  with  a  blackifti  earth,  in  a  fmall  quantity  of 
liquor  of  a  dark  colour,  which  is  feparated  from  the  folution  of 
alkali,  in  the  alcohol,  which  fwims  above  like  an  oil.  Thefe 
cryftals  con6ft  of  the  alkali  faturated  with  the  carbonick  acid, 
and  are  infoluble  in  fpirit  of  wine  j  the  depofition  confifts  of 
filiceous  earth,  lime,  iron,  8cc. 


^T2t5  Compojition  of  Alhalu 

The  cauftick  alkali  in  a  Hate  of  great  purity,  dilTolved  in  the 
v'^cohol,  fwirns  above  the  aqueous  folution  which  contains  the 
•'«fferv«fcent  alkali.  If  the  fpirituous  folution  of  alkali  be  con- 
centrated on  the  fand-bath,  tranfparent  cryftals  are  formed, 
which  confiit  of  the  pure  alkali  itfelf  :  thefe  cryftals  appear  to 
be  formed  by  o.uadrangular  pyramids  inferted  one  in  another  .; 
thty  are  v«iy  deliquefcent,  are  fol able  in  water  and  in  alcohol, 
and  produce  coid  by  their  folution. — Seethe  Journal  de  Phy- 
lique,  1 7^6,  page  40 1 . 

The  alkalis  we  have  juil  fpoken  of  combine  eafily  with  luU 
phur. 

This  combination  may  be  effeded — r.  ^By  the  fufion  of  e- 
qua!  parts  of  alkali  and  fulphur.  2.  By  digefting  the  pure 
and  liquid  alkali  upon  fulphur.-^In  thefe  cafes  the  alkali  be- 
comes of  areddifli  yellow  colour. 

The  folutions  of  fulphur  in  alkali  are  known  by  the  name  of 
Xiivers  of  Sulphur,  Sulphures  of  Alkali,  &c.  They  emit  ati 
ofFenfive  fmell  refembling  that  of  rotten  eggs.  This  is  occa~ 
fioncd  b-y  the  efcape  of  the    {linking  gas,  called   Hepatick  Gas. 

The  fulphur  may  be  precipitated  by  acids  :  and  the  refult  of 
this  precipitation  is  what  the  ancient  chemifts  diftinguifhed  by 
the  name  of  Milk  of  Sulphur,  and  Magiftery  of  Sulphur. 

Thefe  fulphures  or  hepars  diflblve  metals.  Gold  itfelf  may 
be  fo  divided  by  this  means  as  to  pafs  through  filters.  Stahl 
has  fuppofed  that  Mofes  made  ufe  of  this  method  to  enable  the 
Ifraelites  to  drink  the  golden  calf. 

Though  the  analyfis  of  the  two  alkalis  has  not  been  made 
with  Uriel nefs,feveral  experiments  lead  us  to  believe  that  nitro- 
gene  is  one  of  their  principles.  Mr.  Thouvenel,  having  expo- 
fed  wallitd  chalk  to  the  exhalations  of  animal  fubllances  in  pu- 
■irefaclion,  obtained  nitrate  of  pot-a{h,  or  common  nitre.  -^ 
have  repeated  this  experiment  in  a  clofed  chamber  of  £\^  feet 
fquare.  Twenty-five  pounds  of  chalk  well  wafhed  in  warm 
water,  and  expofed  to  tlie  exhalation  of  bullock's  blood  in  pu- 
irefaclion  during  eleven  months,  afforded  nine  ounces  of  nitrate 
of  lime,  in  a  dried  flate  ;  and  three  ounces  one  gros  of  cryftals 
cf  nitrate  of  pot-afh,  or  common  nitre. 

The  repeated  diftillation  of  foaps  decompofes  them,  and  af- 
fords ammoniack.  -  Now  the  analyfis  of  this  laft,  by  Mr.  Ber- 
tiiollet,  proves  the  exiilence  of  nitrogenous  gas  as  one  of  its 
conftituent  parts.  There  is  therefore  room  to  apprehend  that 
nitregene  gas  is  one  of  the  prirciple&of  alkalis. 

The  experiments  of  Mr.  Thouvenel,  as  well  as  my  own, 
lead  to  believe  that  this  gas  when  combined  with  lime  forms 
pot-alh,  or  the  vegetable  alkali  s  while  its  union  with  magnefia 


Volatile  Alhafi.  ftj 

'ms  Soch.  This  laft'  opinion  is  fupported  l>y  ih^  experi- 
nents — ^i.  Of  Dehne,  who  obtained  magneiia  from  foda,  (fee 
Crell's  Chemical  Annals,  1781,  page  53).  2.  Of  Mr.  Deyeux 
who  obtained  fimilar  relults,  even  before  Mr.  Delmc.  3.  Of 
Mr.  Lorgna,  who  obtained  much  magnefia  by  diflblving,  evap- 
orating, and  calcining  foda  repeatedly,  (Journal  dc  Phyfique,. 
1787).  Mr  QfbuTgh  confirmed  thefe  various  experiments  ii5< 
378  c. 


CHAPTER    ir. 

Coitceming  Ammoniack,  cr  the  Volatile  Alkali, 

OIJR  refe?rches  have  not  hitherto  exhibited  more  than  one 
fpecies  of  volatile  alkali.  Its  formation  appears  to  be  owing 
to  putrefaction  ;  and  though  the  didillation  of  fome  fchifti  af- 
fords it,  yet  this  circumftance  may  be  attributed  to  their  origin, 
which  is  pretty  generally  afcribed  to  vegetable  and  animal  de- 
compofition.  We  find  frequently  enough,  in  thefe  fubftances, 
the  print  of  fi.fhes,  which  is  in  favour  of  this  opinion.  Some 
plants  like  wife  afford  volatile  alkali  \  for  which  re?,  fan  they  have 
been  called  Animal  Plants.  But  the  volatile  alkali  is  more 
efpecially  afforded  by  animal  fubdrances  ;  tlie  diriillation  of  all. 
their  parts  affords  it  in  confiderible  abundance.  Horns  are 
employed  in  preference,  becaufe  they  are  refolved  almoft  en- 
tirely into  oil  and  volatile  alkali.  The  putrefaCbion  of  all 
animal  fubllances  produces  volatile  alkali  5  and  in  this  cafe^ 
as  well  as  in  diflillation,  it  is  formed  by  the  combination  of  its 
two  conRituent  parts  :  for  the  analyfis  very  often  fails  in  ex- 
hibiting any  alkali  ready  formed,  in  fuch  parts  as  diillllatioii' 
or  putrefaction  would  abundantly  afford' it  from. 

Almoll  all  the  volatile  alkali  made  ufe  of  in  commerce  or 
medicine,  is  afforded  by  the  decompofition  offal  ammoniack.  iz 
is  even  on  account  of  this  circumftance,  that  the  chemiils  who 
liave  drawn, up  the  New  Nomenclature,  have  diftingulfncd  the 
volatile  alkali  by  the  name  of  Ammoniack. 

To  obtain  ammoniack  in  a  ftate  of  confiderable  purity,  equal- 
parts,  of  fifted  quick-lime  and  muriate  of  ammoniack,  or  com- 
mon fdl  ammoniack,  in  powder  are  mixed.  This  mixture  is  xlizih. 
introduced  into  a  rctort,  to  whicli  a  receiver  and  the  apparatus 
of  Woulie  have  been  adapted.  A  quantity  of  pure  water  is  to 
be  put  into  the  bottles,  correfpondent  to  the  weight  of  the  fak 
employed  ;    and  the  junctures  of  the  veffcl?  are    made-  good: 


I2S  Volatile  Alkali. 

with  the  ufual  lutes.  The  ammoniack  is  difcngaged  in  the 
ftate  of  gas,  at  the  firft  impreffion  of  the  fire.  It  combines 
with  the  water  with  heat ;  and  when  the  water  of  the  firft  bot* 
tie  is  faturated,  the  gas  pafTes  to  that  of  the  fecond,  and  fatu- 
rates  it  in  its  turn. 

Volatile  alkali  is  known  by  its  very  ftrong  but  not  difagree- 
able  fmell.  It  is  eafily  reducible  into  the  ftate  of  gas,  and  pre- 
ferves  this  form  at  the  temperature  of  the  atmofphere.  This 
gas  may  be  obtained  by  decompofing  the  muriate  of  ammoniack 
by  quick-lime,  and  receiving  the  produ£l  over  mercury.  ' 

Alkaline  gas  kills  animals  and  corrodes  the  Ikin.  The  irrita- 
tion is  fuch  that  I  have  feen  pimples  arife  all  over  the  bodies  of 
fome  birds  expofed  to  its  atm-ofphere. 

This  gas  is  improper  for  combuftion ;  but  if  a  taper  be 
gently  immerCed  in  it,  the  flame  is  enlarged  before  it  goes  out, 
and  the  gas  fufFers  a  decompofition.  Alkaline  gas  is  lighter 
than  atmofpherick  air  ;  and  has  even  been  mentioned,  on  ac- 
count of  its  lightnefs,  as  a  proper  fubftance  to  fill  balloons. 
The  count  De  Mille  propofed  to  place  a  brazier,  or  velTcl 
containing  fire,  under  the  balloon,  to  keep  the  gas  in  its  great- 
eft  ftate  of  expanfibility. 

The  experiments  of  Dr.  Prieftley,  who  changed  alkaline  gas 
into  hydrogene  gas  by  means  of  the  ele^lrick  fpark  ;  thofe  of 
the  chevalier  Laudriani,  who,  by  pafhng  the  fame  gas  through 
ignited  glafs  tubes,  obtained  a  large  quantity  of  hydrogenous 
gas — occafioned  a  fufpicion  of  the  exiftence  of  hydrogene  a- 
mon;:^  the  principles  of  alkaline  gas.  But  the  experiments  of 
Mr.  Berthollet  have  removed  all  doubts  on  this  fubjedl  ;  and 
all  obfervations  appear  to  unite  in'  authorifing  us  to  confider 
this  alkali  as  a  compound  of  the  nitrogenous  and  hydrogenous 
g'^fes.  ^  ' 

1.  If  the  oxigenated  muriatick  acid  be  mixed  with  very  pure 
ammoniack,  an  efFervefcence  takes  place  with  a  difengagement 
of  nitrogenous  gas,  a  production  of  water,  and  a  converfion  of 
the  oxigenated  acid  into  the  ordinary  muriatick  acid.  In  this 
beautiful  experiment,  the  water  which  is  produced  is  formed  by 
the  combination  of  the  hydrogene  of  the  alkali  and  the  oxigene 
of  the  acid  ;  and  the  nitrogene  gas  being  fet  at  Hberty,  is  dif- 
fipated. 

2.  When  the  nitrate  of  ammoniack  is  expofed  to  diftillation, 
nitrogene  gas  is  obtained,  and  a  greater  quantity  of  water  is 
found  in  the  receiver  than  the  fait  itfclf  contained.  After  the 
operation,  the  ammoniack  is  found  no  longer  to  exift.  The 
water  of  the  receiver  is  flio^htly  charged  with  a  fmall  quantity  of 
nit:rick  acid,  which  had  paffed  over.     In  this  cafe,  the  hydrogene 


^^  Fblati/e  AlkalL  12^ 

^K"  tlie  alkali,  and  the  oxigene  of  the  acid  form  the  water  In  the 

^^fcceiver,  M'hile  the  nitrogenous  gas  efcapcs. 

^^  If  the  oxides  of  copper  or  gold  be  heated  with  ammoniacal 
'gas,  the  product  is  water  and  nitrogenous  gas,  and  the  metals 
"ire  reduced. 

I  have  obferved  that  the  oxides  of  arfenick,  being  digefted 
with  aramoniack,  are  reduced,  and  often  form  octahedral  cryl- 
tals  or  arfenick.  In  this  cafe  there  is  a  difengagement  of  nitro- 
gene  gas,  and  a  formation  of  water. 

It  very  often  happens  when  metals,  fuch  as  copper  or  tin, 
are  diUblved  by  means  of  the  nitrick  acid,  that  an  abforption 
of  air  takes  place,  inflead  of  a  difengagement  of  nitrous  gas,  as 
might  be  expelled  :  I  have  feen  feveral  perfons  very  much  em- 
barrafled  in  fuch  cafes,  and  I  have  often  been  fo  myfelf.  This 
phenomenon  takes  place  more  efpecially  when  a  very  concentra- 
ted acid  is  made  ufe  of,  and  the  copper  is  in  fine  filings  :  in. 
this  cafe  am.mcniack  is  produced.  I  have  Ihewn  this  facSb  to 
my  auditors  long  before  I  was  acquainted  with  the  theory  of  its 
formation.  That  which  led  me  to  fufpe<ft  its  exiftence,  was 
the  blue  colour  which  the  folution  takes  in  this  cafe.  Tiiis 
ammoniack  is  produced  by  the  combination  of  the  hydrogens 
of  the  water  with  the  nitrogene  gas  of  the  nitrick  acid  ;  while 
the  oxigene  of  the  fame  acid,  and  that  of  the  water,  oxided  tht 
metal,  and  prepared  it  for  folution.  It  is  to  a  fimilar  caufe  that 
we  muft  refer  the  experiment  of  Mr.  John  Michael  HaufTmau 
of  Colmar,  who  by  pafiing  nitrous  gas  through  a  certain  quan- 
tity of  precipitate  of  iron,  in  the  mercurial  apparatus,  obferved 
that  this  gas  was  fpeedily  ablbrbed,  and  the  colour  of  the  iron 
clian^ed  •,  at  the  fame  time  that  vapour  of  ammoniack  was 
found  in  the  vefiels.  It  is  by  a  fimilar  theory  we  may  account  for 
the  formation  of  alkaline  gas,  by  the  mixture  of  hepatick  gas  and 
nitrous  gas  over  mercury,  as  Mr.  Kirwan  obferves. 

Mr.  Auftin  formed  ammoniack  ;  bv.t  he  obferved  that  the  com- 
bination of  nitrogenous  gas  with  the  bafe  of  hydrogene  does  not 
take  place  unlefs  this  lad  is  in  a  ftatc  of  great  condenfation. 

The  formation  of  ammoniack  by  diftillation  and  putrefadion, 
appears  to  me  likewife  to  indicate  its  conftituent  parts.  In  fa<fl, 
there  is  in  both  thefe  operations  a  difengagement  of  hydrogene 
and  nitrogene  gas,  and  their  combination  produces  ammoniack. 
Mr.  Berihollct  has  proved,  by  the  way  of  decompofition,  that 
one  thoufand  parts  of  ammoniack,  by  weight,  are  compofed  of 
about  eight  hundred  and  feven  of  nitrogene  gas,  a^id  one  hun- 
dred and  ninety-tliree  of  hydrogene  gas. — Seethe  collection  of 
the  Royal  Academy,  1784,  page  316. 

According  to  Dr.  Auftin,  tlie  nitrogeiVc  gas  is  in  proportion 
to  tlie  liydrogene,  as  one  hundred  and  twenty-one  tQ  thirty-two. 
K. 


13*  General  Prcperties  of  Acids, 

SECTION  IX. 

Concerning  the  Conr^binatlon  of  Oxigenc   v/ith  certain  Bafcs  forming 

AriHs. 


I 


T  appears  to  be  out  of  doubt,  that  the  bodies  which  we 
are  agreed  to  call  Acids,  are  combinations  of  vital  Air  with  a  cer- 
tain elementary  fubftance.  The  analyfis  of  alnioil  all  the  Acids, 
"whofe  component  parts  are  known,  eftablifhes  this  truth  in  a 
pofitive  manner;  and  it  is  on  account  of  this  property  that  the 
denomination  of  Oxigenous  Gas  has  been  given  to  vital  air. 

Every  fubftance  which  poiTeires  the  following  properties  is  call- 
ed an  Acid  : 

A.  The  word  fcur,  which  is  ufually  employed  to  denote  the 
impreflion  or  lively  and  fliarp  fenfation  produced  on  the  tongue 
by  certain  bodies,  may  be  regarded  as  fynonymous  to  the  word 
acid.  The  only  difference  which  may  be  eftabliflied  between 
them  is,  that  the  one  denotes  a  weak  fenfation,  whereas  the 
other  comprehends  all  the  degrees  of  force  from  theleafl:  percep- 
tible tafte  to  the  greatefl  degree  of  caufticity.  We  fay,  for  ex- 
ample, that  verjuice,  goofeberries,  or  lemons,  -dre  four  ;  but  we 
ufe  the  word  acid  to  exprefs  the  impreflion  which  the  nitrick, 
lulphurick,  or  muriatick  acids  make  upon  the  tongue. 

The  caufticity  of  acids  appears  to  arife  from  tlieir  ftrong  ten- 
dency fro  combination  ;  and  it  is  from  this  property  that  the 
immortal  Newton  has  defined  them  to  be  bodies  wliich  attradl 
and  are  attra^ed. 

It  is  likewife  from  this  property  that  certain  chcmifts  havt 
fuppofed  acids  to  be  pointed  bodies. 

On  account  likewife  of  this  decided  tendency  to  combination 
which  acids  poiTefs,  it  feldom  happens  that  we  find  them  in  a 
difengaged  ftate. 

B.  A  fecond  property  of  acids  is  that  of  changing  certain  blue 
vegetable  colours  into  red,  fuch  as  the  colour  of  turnfole,  fyr-* 
up  of  violets,  &c.  Thefe  two  re-agents  are  commonly  ufed 
to  afccrtain  the  prefence  of  acids. 

The  tin6ture  of  turnfole  is  prepared  by  lightly  infufing  in 
water  that  fubftance  which  is  known  in  common  under  the 
name  of  Turnfole  or  Litmus.  If  the  water  be  too  highly 
charged  with  the  colouring  matter,  the  infufion  has  a  violet 
tinge,  and  mufl  in  that  cafe  be  diluted  with  water  until  it  be- 
comes blue.  The  tincture  of  turnfole,  when  expofed  to  the 
fun,  becomes  red,  even  in  cbfcd  'velTels  \  and  foms  time  after- 


IXjeneral  Properties  of  jicids.  1 3  X 

prds  the  colouring  part  is  difengaged,  and  falls  dov/n  in  the 
prm  of  a  mucilaginous  difcoloured  fubftance.  Alcohol  may 
\t  ufedinflead  of  water  in  the  preparation  of  this  tincture. 
It  is  generally  fuppofed  that  the  turn fole  fabricated  in  Hol- 
and  is  nothing  more  than  the  colouring  matter  extracted  from 
the  rags  or  cloths  of  turnfole  of  Grand-Galargues,  and  precipi- 
tated on  a  marly  earth.  Thefe  rags  are  prepared  by  impreg- 
nating them  v/ith  the  juice  ofnightfiiadc  (morrellej,  and  ex- 
pofing  them  to  the  vapour  of  urine,  which  developes  their  blue 
colour.  The  rags  are  fent  into  Holland,  wliich  has  given  rife 
to  the  opinion  that  they  are  ufed  in  the  fabrication  of  turnfole  y 
but  fubfequent  enquiries  have  taught  me  that  thefe  cloths  are 
fent  to  the  dealers  in  cheefe,  wlio  extract  a  colour  by  infufion 
and  wafti  their  cheefes  with  it,  to  give  them  a  red  colour.  I 
am  convinced,  by  the  analyfis  of  turnfole,  that  the  colouring 
matter  is  of  the  fame  nature  as  that  of  archil  (orfeiilc)  :  and  that 
this  principle  is  fixed  on  a  calcareous  earth,  and  a  fmall  quan- 
tity of  pot-afh.  In  confequence  of  this  analyfis,  I  have  endeav- 
oured to  caufe  the  liken  parelus  of  Auvergne  to  ferment  with  u- 
rine,  lime  and  alkali,  and  I  obtained  a  pafle  fimilar  to  that  of 
turnfole.  The  addition  of  alkali  appears  to  me  to  be  ne- 
ceffary  to  prevent  the  developement  of  the  red  colour,  which 
when  combined  with  the  blue  forms  the  violet  of  the  archil. 

When  any  concentrated  acid  is  to  be  tried  with  fyrup  of 
violets,  there  are  two  particulars  to  be  attended  to.  i.  The 
fyrup  of  violets  is  often  green,  becaufe  the  petal  of  the  violet 
contains  a  yellow  part  at  its  bafe,  which  when  combined  with, 
the  blue,  forms  this  green  colour  :  it  is  therefore  effential  to 
employ  only  the  blue  of  the  petal  in  order  to  have  a  beautiful 
blue  infuCon.  2.  Care  muft  be  taken  to  dilute  the  fyrup 
with  a  certain  quantity  of  water  ;  becaufe  otherwife  concen* 
trated  acids,  fuch  as  the  fulphurick,  would  burn  it  and  form 
a  coal. 

The  fimple  infufion  of  violets  may  be  ufed  inflead  of  the 
fyrup. 

The  colouring  matter  of  indigo  is  not  fenfible  to  the  im- 
preffion  of  acids.  The  fulphurick  acid  diffolves  it,  without 
altering  the  colour. 

C.  A  third  chara£ler  of  acids  is,  that  they  effervefce  with 
alkalis  ;  but  this  property  is  not  general,  i.  Becaufe  the  car- 
bonick  acid,  and  almofl:  all  weak  acids,  cannot  be  diftinguiflied 
by  this  property.  2.  Becaufe  the  pureft  alkalis  combine  with 
^cids,  v/ithout  motion  or  effervefcence. 

Is  there  not  a  fingle  acid  in  nature,  of  wlucli.  the  others 
may  be  only  modifications  ?  4 


^s 


General  Properties  of  Acids, 


Paracelfus  admitted  an  iinlverfal  principle  of  acidity,  which 
communicated  tafte  and  folubility  to  aH  its  compounds, 

Bechcr  believed  that  this  principle  was  compofed  of  water  and 
vitrifiable  earth.  Stahl  endeavoured  to  prove  that  the  fulpurick 
:i"cid  was  the  univerfa)  acid  and  his  opinion  was  adopted  by  mod 
chcmifts  for  a  long  time. 

Long  after  the  time  of  Stahl,  Meyer  maintained  that  the  acid 
clement  was  contained  in  fire.  This  fyftem,  which  is  founded 
on  certain  known  fa£ls,  has  had  its  fupporters. 

The  chevalier  Landriani  imagined  he  had  fucceeded  in  redu- 
cing ail  the  acids  to  the  carbonick  acid  ;  becaufc  by  treating 
them  all  with  different  fubftances,  he  obtained  this  laft  as  the 
conflant  refult  of  his  anaiyfis.  He  was  led  into  an  errour,  for 
v/ant  of  having  fufficiently  attended  to  the  decompofition  of  the 
acids  he  made  ufe  of,  and  the  combination  of  their  oxigene 
■with  the  carbone  of  the  bodies  which  entered  into  his  experi- 
ments, and  produced  the  carbonick  acid. 

Laftly,  the  ftrift  analyfis  and  fynthefis  of  moft  of  the  known 
acids,  have  proved  to  Mr.  Lavoifier,  that  oxigene  is  the  bafe  of 
all  of  them  ;  and  that  their  differences  and  varieties  arife  only 
from  the  fubftances  with  which  this  common  principle  is  com- 
bined. 

Oxigene  united  with  metals  forms  oxides  ;  and  among 
thefe  lait  there  are  fome  which  poffefs  acid  charadlers,  and  are 
claiTed  among  acid  fubftances. 

Oxigene  combined  with  inflammable  fubftances^  fuch  as  ful- 
phur,  carbone,  and  oils,  forms  other  acids. 

The  a£lion  of  acids  upon  bodies  in  general,  cannot  be  under-, 
fkood  but  by  founding  our  explanations  upon  the  data  which 
we  have  eftablifhed  refpeiling  the  nature  of  their  conftituent. 
parts. 

The  adhefion  of  oxigene  to  the  bafe  Is  more  or  lefs  ftrong 
m  the  fcveral  acids,  and  confequently  their  decompofition  is 
more  or  lefs  eafy  ;  as,  for  example,  in  metallick  folutions,  which 
«lo  not  take  place  excepting  when  the  metal  is  in  a  ftate  of  an 
oxide.  The  acid  which  will  yield  its  oxigene  with  the  greateft 
facility  to  oxide  the  metal,  will  ha^-e  the  moft  powerful  action 
upon  it.  Hence  it  happens,  that  the  nitrickand  the  nitro-mu- 
riatick  acids  are  thofe  which  diffolve  metals  the  moft  readily ; 
and  hence  like  wife  it  happens  that  the  muriatick  acid  difTolves 
the  oxides  more  eafily  than  the  metals,  while  the  nitrick  acid  ad& 
contrariwlfe  :  hence  alfo  it  arifes  that  this  laft  afts  fo  power- 
fully upon  oils,  &c. 

It  is  impcffible  to  conceive  and  explain  the  various  phenom- 
ena prefented  to  us  by  acids  in  their  0|ierations,  if  we  have  r: 


Carbotnck  Acidy  or  Fixed  Air,  133 

idea  of  their  conftituent  principles,  Stahl  would  not  have  be- 
lieved in  the  formation  of  fulphur,  if  he  had  underftood  the 
decompofition  of  the  fulphurick  acid  upon  charcoal  j  and  if  wc 
except  the  combinations  of  acids  with  alkalis,  and  with  certain 
earths,  thcfe  fubltances  are  either  totally  or  partially  decompofed 
in  all  the  operations  made  with  them  upon  metals,  vegetables, 
and  animals,  as  we  ^hali  find  by  obferving  the  feveral  phenome- 
na exhibited  in  thefe  cafes  refpeclively. 

We  lliall  at  prefent  treat  only  of  fome  of  the  acids,  and  (hall 
ilirect  our  attention  to  the  others  in  proportion  as  we  (hall  have 
occafion  to  treat  of  the  various  fubitances  which  afford  them  ; 
we  Ih.all  attend  in  preference  to  thofe  which  are  the  beft  known, 
and  which  have  the  greateft  influence  in  the  operations  of  na- 
ture^  as  well  as  in  thofe  of  our  laboratories. 


CHAPTER  I. 

Concerning  the  Carbonick  Acid. 

THIS  acid  is  almofl  always  obferved  in  the  ftate  of  gas.  We 
find  that  the  ancients  were  in  fome  meafure  acquainted  with  it. 
Van  Heimont  called  it  Gas  Silvellre,  the  gas  of  muft,  or  of  the 
vintage.  Becher  himfelf  had  a  confiderable  accurate  notion  o£ 
it,  as  appears  by  the  following  paffage  :  <'  Diftinguitur  autena 
"  inter  fermentationcm  apertam  et  claufem  ;  in  aperta  potus 
<'  fermtntatus  fanior  eft,  fed  fortior-4n  claufa :  caufa  ell,  quod 
"  evaporantia  rarefatla  corpufcula,  imprimis  magna  adhuc  fil- 
<*  veftrium  fpirituum  copia,  de  quibus  antea  egimus,  retineatur, 
«  et  in  ipfuni  potum  fe  precipitet,  undc  valde  eum  fortem 
«  reddit." 

Hoffmann  attributed  the  virtue  of  mod  mineral  waters  to  an 
claflick  fpirit  contained  in  them. 

Mr.  Venel,  a  celebrated  profeffor  in  the  fchools  at  Montpel- 
Her,  proved  in  1 750,  that  the  waters  of  Seltzer  owed  their  virtue 
to  a  f  uperabundant  portion  of  air. 

In  1755,  Dr.  Black  of  Edinburgh  advanced  that  limeftone 
contains  much  air  of  a  different  nature  from  common  air.  He 
affirmed  that  the  difengagement  of  this  air  converted  it  into  lime, 
nnd  that  by  the  reftoration  of  this  air  calcareous  ftone  was  regen- 
erated. In  the  year  1 746,  Dr.  M'Bride  fupported  this  do£lrine 
>vith  new  facts.  Mr.  Jacquin,  profeffor  of  Vienna,  refumed 
the  fame  purfiyt,  multiplied  experiments  on  the  manner  of  ex- 
tra<^ing  this  air,  and  added  other  proofs  in  confirmation  that  the 


1 3  4  General  Properties  and 

abfence  of  the  air  rendered  alkalis  cauftick,  and  formed  lime, 
D^.  Prieftly  cxliibited  all  the  perfpicuity  and  precifion  on  this 
fubjea  which  might  be  expedted  from  his  abilities,  and  his  fj^ill 
in  making  experiments  of  this  kind.  This  fubftance  was  then 
known  by  the  name  of  Fixed  Air.  In  1772,  Bergmann  proved 
that  it  is  an  acid,  which  he  called  by  the  name  of  Aerial  Acid? 

Since  the  time  of  this  celebrated  chemifl,  it  has  been  diflin- 
guiflied  by  the  names  of  Mephitick  acid,  Cretaceous  acid,  &c.  : 
and  as  foon  it  was  proved  to  con  fill  of  a  combination  of  oxigen 
3ind  carbone,  or  pure  charcoal,  the  name  of  carbonick  acid  v/:i. 
appropriated  to  it. 

The  carbonick^acid  is  found  in  three  different  dales.  i.  In 
that  of  gas.  2.  In  a  flate  of  mixture.  3.  In  a  itate  of  combina-- 
tion. 

It  is  found  in  the  flate  of  gas  at  the  Grotto  del  Cano,  near 
Naples  ;  at  the  well  of  Perols,  near  Montpellier ;  in  that  of 
Negrae  in  Vivarais  upon  the  furface  of  the  lake  Avcrno  in  Italy, 
and  on  thofe  of  feveral  fprings  ;  in  various  fubterraneous  pla- 
ces, fuch  as  tombs,  cellars,  neccimries,  he.  It  is  difengaged 
in  this  form  by  the  decompofition  of  vegetables  Iieaped  together, 
by  the  fermentation  of  wine  or  beer,  by  the  putrefatlion  of 
animal  matters,  &c. 

It  cxifts  in  the  ftate  of  fimple  mixture  iu  mineral  waters, 
fmce  in  thefe  it  polTeffes  all  its  acid  properties. 

It  exifts  in  a  flate  of  combination  in  flone,  common  magnefia  ^ 
alkalis,  &c. 

Various  procefTes  are  employed  to  colledl  it,  according  to  th. 
flate  in  which  it  is  found. 

I.  When  the  carbonick  acid  exifts  In  the  ftate  of  gas.  It  may- 
be collecled — i.  By  filling  a  bottle  v/ith  water,  and  emptying 
it  into  the  atmofphere  of  this  gas  :  the  acid  takes  the  place  of 
the  water,  and  the  bottle  is  afterwards  corked  to  retain  it.  2. 
By  expofing  lime  water,  cauftick  alkalis,  or  even  pure  water,  in 
its  atmofphere  :  the  gafeous  acid  mixes  or  combines  with  thefe 
fubftances  :  and  may  be  afterwards  extracted  by  re-agents, 
which  we  fliall  proceed  to  defcribe. 

II.  When  the  carbonick  acid  exiils  in  a  ftate  of  combination, 
it  may  bo  extracled — i.  By  diftillation  with  a  flrong  heat.  2. 
By  the  re-a£lion  of  other  acids,  fuch  as  the  fulphurick  acid, 
which  has  the  advantage  of  not  being  volatile,  and  confequent- 
ly  is  not  altered  by  its  mixtures  with  the  carbonick  acid  which 
is  difengaged. 

III.  When  the  carbonick  acid  exlfls  in  the  flate  of  fimpIc 
mixture,  as  in  water,  brifk  wines,  &c.  it  may  be  obtained — i. 
By  agitation  of  the  liquid  which  contains  it  ;    as  Mr.  Venel 


Habitudes  of  Carhonkk  Add,  13^ 

praflifed,  by  making  ufe  of  a  bottle  to  which   he  adapted  a 
moiftened  bladder. 

2.  By  diftillation  of  the  fame  fluid. — Thefe  two  firft  meth- 
ods are  not  accurate. 

3.  The  procefs  indicated  by  Mr.  Gioanetti,  confifts  in  pre- 
cipitating the  carbonick  acid  by  means  of  lime-water,  weighing 
the  precipitate,  and  deducing  thirteen  thirty-fecond  parts  for 
the  proportion  of  carbonick  acid  ;  it  having  been  deduced  from 
flnalyfis,  by  this  celebrated  phyfician,  that  thirty-two  parts  of 
carbonate  of  lime  contain  fevcnteen  lime,  two  water,  and  thir- 
teen acid. 

This  fubftance  is  an  acid,  as  is  proved — i.  Becaufe  tindure 
cf  turnfole,  agitated  in  a  bottle  filled  with  this  gas,  becomes  red. 
2.  Ammoniack,  or  volatile  alkali,  poured  into  a  veflel  filled  with 
this  g^s,  is  neutralized.  3.  Water  impregnated  with  this  gas 
is  flrongly  fub-acid.  4.  It  neutralizes  alkalis,  and  caufes  them 
to  cryftallize. 

It  remains  at  prefent  to  examine  the  properties  of  this  acid 
gas. 

A.  It  is  unfit  for  refpiration.  Hidory  informs  us  that  two 
flaves  whom  Tiberius  caufed  to  defcend  into  the  Grotto  del 
Cano,  were  immediately  ftifled  ;  and  two  criminals  that  Peter 
de  Toledo  caufed  to  be  fliut  in  there,  fuffered  the  fame  fate. 
The  abbe  Nollet,  who  had  the  courage  to  refpirc  the  vapour, 
perceived  a  fuffocating  fenfalion,  and  a  flight  degree  of  acidity, 
which  produced  coughing  and  fneezing.  Pilatre  de  Rofier, 
who  prefents  himfelf  to  our  notice  on  all  occafions  wherein 
danger  was  to  be  faced,  caufed  himfelf  to  be  faftened  by  cords 
fixed  under  his  arms,  and  defcended  into  the  gafeous  atmof- 
phere  of  a  back  of  beer  in  fermentation.  He  had  fcarcely  en- 
tered into  the  mephitis  before  flight  prickings  obliged  him  to 
ihuthis  eyes  \  a  violent  fuflx)cation  prevented  him  from  refpir- 
ing ;  he  felt  a  giddinefs,  accompanied  with  thofe  noifes  which 
charadlerize  the  apoplexy  :  and  when  he  was  drawn  up,  his 
fight  remained  dim  for  feveral  minutes  ;  the  blood  had  filled  the 
jugulars  ;  his  countenance  had  become  purple  ,  and  he  neither 
heard  nor  fpoke  but  with  great  difiiculty  ;  all  thefe  fymptoms, 
liowever,  disappeared  by  degrees. 

It  is  this  gas  which  produces  the  many  unhappy  accidents  at 
the  opening  of  cellars,  in  places  where  wine,  cider,  or  beer  are 
fuffered  to  ferment.  Birds  plunged  into  the  carbonick  acid  gas, 
fuddenly  perifti.  The  famous  Lake  of  Averno,  vvhere  Virgil 
placed  the  entrance  of  hell,  exhales  fo  large  a  quantity  cf  car- 
bonick acid,  that  birds  cannot  fly  over  It  with  impunity.  When 
the  waters  of  Boulidou  of  Perols  are  dry,  fuch  birds  as  attempt 


33^5  General  Properties  and 

to  quench  their  third  in  the  clefts,  are  envebpcd  In  the  mephit- 
ick  vapour  and  die. 

Frogs,  plunged  in  an  atmofphere  of  carbonlck  acid,  live  from 
forty  to  fixty  minutes,  by  fufpendmg  their  refpiration. 

Infects  are  rendered  torpid  after  a  certain  time  of  remaining 
in  this  air  \  but  they  refumc  their  livelinefs  the  moment  they 
are  expofed  to  the  free  air. 

Bergmann  pretended  that  this  acid  fufFocates  by  extinguifli- 
ing  irritability  :  he  founds  his  opinion  upon  the  circumftance  of 
his  having  taken  out  the  heart  of  an  animal  which  had  died  in 
the  carbonlck  acid,  before  it  vv-as  cold,  and  it  exhibited  no  fign  of 
irritability.  The  chevalier  Landriani  has  proceeded  Hill  further : 
for  he  affirms  that  this  gas  extinguifhes  irritabihty,  even  when 
applied  to  the  Ikin  •,  and  has  afTerted  that,  by  tying  a  bladder  full 
of  this  gas  to  the  neck  of  a  fowl,  in  fuch  a  manner  tkat  the 
head  only  of  the  animal  was  in  the  open  air,  and  the  whole  body 
enveloped  in  the  bladder,  the  fowl  immediately  periflied.  The 
abbe  Fontana  has  repeated  and  varied  this  experiment  on  fev^ral 
animals,  none  of  which  died. 

The  count  Morrozzo  publifhed  experiments  made  in  the  pref- 
ence  of  Dr.  Cigna ;  the  refults  of  which  appear  to  invalidate 
the  confequences  of  the  celebrated  Bergmann  :  but  it  is  to  be 
obferved,  that  the  chemift  of  Turin  caufed  his  animals  to  die 
only  in  air  vitiated  by  the  death  of  another  animal ;  and  that  in 
this  circumftance  the  nitrogene  gas  predominates.— See  the 
Journal  de  Phyfique,  torn.  xxv.  p.  112. 

B.  The  carbonlck  acid  is  improper  for  vegetation.  Dr. 
Priellley  having  kept  the  roots  of  ieveral  plants  in  water  impreg- 
nated with  the  carbonlck  acid,  obferved  that  they  all  perilhed  ; 
and  in  thofe  inflances  where  plants  are  obferved  to  vegetate  in 
water  or  in  air  which  contains  this  gas,  the  quantity  of  gas  is 
very  fmall. 

Mr.  Senebier  has  even  obferved,  that  plants  which  are  fufFer- 
cd  to  grow  in  water  (lightly  acidulated  with  this  gas  emit  a 
much  larger  quarrtity  of  oxigenous  gas  ;  becaufe,  in  this 
cafe,  the  acid  is  decompofed,  the  carbonaceous  principle 
combines  and  is  fixed  in  the  vegetable,  while  the  oxigene  is 
thrown  otT. 

I  have  obferved  that  thofe  fungi  which  are  formed  in  fubter- 
raneous  places,  are  almoft  totally  refolved  into  carbonick  acid ; 
but  if  thefe  vegetables  be  gradually  expofed  to  the  a£lion  of  light, 
the  proportion  of  acid  diminiflies ;  while  that  of  the  coaly 
principle  augments,  and  the  vegetable  becomes  coloured.  I 
have  purfued  thefe  experiments  with  the  greatcft  care  in  a  coal 
mine. 


Ilahltudes  of  Carhonich  Acid.  I37 

C.  The  carbonlck  acid  is  eafily  diflblved  In  water.  Water 
impregnated  with  this  acid  poflefles  very  valuable  medicinal 
qualities ;  and  feveral  apparatus  have  been  fucceffively  Invented 
to  facilitate  this  mixture.  The  apparatus  of  Nooth,  improved 
by  Parker  and  Magellan,  Is  one  of  the  mod  ingenious.  On 
tills  fubject  the  Encyclopedic  Methodique  may  be  confulted,  ar- 
ticle Acide  Mephitique. 

The  natural  acidulous  mineral  waters  do  not  differ  from 
thefe,  excepting  in  confequence  of  their  holding  other  princi- 
ples in  folution  ;  and  they  may  be  perfedly  Imitated  when  theij: 
analyfis  is  well  known.  It  is  abfurd  to  think  that  art  Is  incapa- 
ble of  imitating  nature  In  the  compofition  of  mineral  waters. 
It  mud  be  admitted  that  the  procefles  of  nature  are  abfolutely 
unknown  to  us,  in  all  the  operatioirs  which  relate  to  life  ;  and 
we  cannot  flatter  ourfelves  with  the  hope  of  imitating  her  in 
thefe  circumilances.  But  when  the  queftion  relates  to  an  ope- 
ration purely  mechanical,  or  confifting  of  the  folution  of  certain 
known  principles  in  water,  we  can  and  ought  to  perform  It  even 
Hill  better,  as  we  have  the  power  of  varying  the  dofes,  and  pro- 
portioning the  efficacy  of  any  artificial  mineral  water  to  the 
purpofes  to  which  it  is  intended  to  be  applied. 

D.  The  carbonlck  acid  gas  is  heavier  than  common  air.  The 
proportion  between  thefe  two  airs  in  weight,  according  to  Mr. 
Kirwan,  is  45,69  to  68,74.  The  proportion,  according  to  the 
experiments  of  Mr.  Lavoifier,  Is  48,81  to  69,50. 

This  confiderable  weight  caufes  it  to  occupy  the  loweft  fitu- 
ations  and  even  gives  it  the  property  of  being  poured  out  from 
one  vefTel  to  another,  fo  as  to  difplace  the  atmofpherick  air. 
This  truly  curious  phenomenon  was  obferved  by  Mr.  De  Sauva- 
ges,  as  may  be  feen  in  his  DlfTertation  upon  air,  which  was 
crowned  in  Marfeilles,  in  1750. 

It  appears  to  be  proved,  by  fulTicIent  experiments,  that  the 
carbonlck  acid  is  a  combination  of  carbone,  or  pure  charcoal, 
and  oxigcne.  i.  The  oxides  of  mercury,  when  diftilled,  are 
reducible  without  addition,  and  afford  only  oxigenous  gas  5  but 
if  a  fmall  quantity  of  charcoal  be  mixed  with  the  oxide,  the 
produ(St  which  comes  over  confifts  of  carbonlck  gas  only,  and 
the  weight  of  the  charcoal  is  diminifhed. 

2.  If  well-made  charcoal  be  ignited,  and  plunged  Into  a  vef- 
fel  filled  with  oxigenous  gas,  and  the  veflel  be  Inflantly  clofed, 
the  charcoal  burns  rapidly,  and  at  laft  goes  out  :  the  produdl:  in 
this  experiment  is  carbonick  acid,  which  may  be  feparated  by 
tlie  known  procefles  ;  the  remainder  is  a  fmall  quantity  of  oxi- 
genous gas,  which  may  be  converted  into  carbonick  acid  by  the 
fame  treatment. 


J38  Carbonate  of  Pot-AJB. 

In  thefe  experiments  I  fee  nothing  but  charcoal  and  oxigenou* 
gas  j  and  the  confequence  deduced  is  fimple  and  natural. 

The  proportion  of  charcoal  is  to  that  of  oxigene  as  12,0288^ 
to  56,687. 

When  the  carbonick  acid,  in  fome  cafes,  is  obtained  by  burn- 
ing hydrogenous  gas,  it  arifes  from  carbone  held  in  folution  in 
•this  gas.  The  carbone  may  even  be  diflblved  in  hydrogenous 
gas,  by  expofmg  it  to  the  focus  of  the  burning  mirror  in  th« 
mercurial  apparatus,  under  a  glafs  vefTel  filled  with  this  gas. 

The  hydrogenous  gas  which  is  extra£led  from  a  mixture  of  ful- 
phurick  acid  and  iron,  holds  more  or  lefs  of  charcoal  in  folution  j 
becaufe  iron  itfelf  contains  this  fubdance  in  a  greater  or  lefs 
quantity,  as  is  afcertained  by  the  fine  experiments  of  MeiTrs.' 
BerthoUet,  Monge,  and  Vander  Monde. 

The  alkalis,  fuch  as  we  ufually  meet  with  them,  contain  car-' 
bonick  acid  ;  and  it  is  this  acid  which  modifies  them,  and  dimin- 
ilhes  their  energy,  at  the  fame  time  that  it  communicates  to  thent 
the  property  of  effervefcing.  We  may  therefore  confider  alka- 
lis as  carbonates  with  excefs  of  alkali ;  and  it  is  eafy  to  faturate 
this  fuperabundant  alkali,  and  to  form  true  cryftallizable  neutral 
falt^. 


ARTICLE  t 

Carbonate  of  Pot-Afli* 

The  carbonate  of  pot-afh  was  formerly  diftlngmfhed  by  the 
name  of  Cretaceous  Tartar.  The  method  of  caufing  oil  of  tar*- 
tar  to  cryftallize,  has  long  been  known.  Bonhius  and  Montet 
have  fucceffively  fhewn  thefe  procefTes :  but  the  fimpleft  confills 
in  expofing  an  alkaline  folution  in  an  atmofphere  of  the  acid 
gas  which  is  difengaged  in  the  vinous  fermentation  ;.  the  alkali 
becomes  faturated,  and  forms  tetrahedral  prifmatick  cryftals  ter- 
minated by  very  fhort  four-fided  pyramids. 

I  have  feveral  times  obtained  thofe  cryftals  in  the  form  of 
e^uadrangular  prifms,  with  their  extremities  cut  off  llantwife. 

This  neutral  fait  na  longer  poiTefles  the  urinous  tafte  of  the 
alkali,  but  exhibits  the  penetrating  tafte  of  neutral  falts,  and 
may  be  employed  in  medicine  with  the  greateft  fuccefs.  I  have 
been  a  witnefs  to  its  being  taken  in  the  dofe  of  one  dram  (grofs)- 
without  the  leaft  inconvenience. 

This  fait  poffefles  an  advantage  beyond  the  fait  of  tartar,  in 
being  lefs  cauftick,  and  always  of  the  fame  virtue. 


^P  Carbonate  of  Ammaniach,  .13^ 

'It  contains,  according  to  the  analyfis  of  Bergmann,  twenty 
|)aTts  acid,  forty-eight  alkali,  and  thirty-two  water,  in  the  quintal. 

It  does  not  attract  the  humidity  of  the  air.  I  have  preferved 
«fome  of  it  for  feveral  years  in  a  capfule,  without  any  appearance 
joi  alteration. 

The  carbonate  of  pot-afh  is  decompofed  byfilexin  a  fufficient 
jieat,  which  occafions  a  confiderable  boiling  or  ebullition.  The 
Tefidue  is  glafs,  in  which  the  alkali  is  in  the  cauftick  ftate. 
Lime  decompofes  the  carbonate^  by  uniting,lo;,the  acid  ;  an4 
acids  produce  .the  fanpie  effe(5,  by  cpmbining  with  the  alkaliue 
'bafes. 

ARTICLE  H. 

•     Carbonate  of  Soda. 

The  denominations  of  Aeriated  Mineral  Alkali,  Cretaceous 
Soda,  ^c.  liave  been  fucceffively  given  to  this  kind  of  carbonate. 

The  mineral  alkali,  in  its  natural  ftate,  contains  a  greater 
quantity  of  carbonick  acid  than  the  vegetable  ;  and  nothing  more 
is  neceflary  than  to  diflblve  it,  and  duly  evaporate  the  water,  in 
forder  to  obtain  it  in  cryftals. 

Thefe  cryftals  are  ufually  rhomboidal  o6lahedrons  and  fome- 
times  have  the  form  of  rhomboidal  laminae,  applied  obliquely 
one  upon  the  other,  fo  that  they  refemble  tiles. 

This  carbonate  efflorefces  in  the  air. 

One  hundred  parts  contain  fixteen  parts  acid,  twenty  alkali, 
and  fixty-four  water. 

The  affinity  of  its  bafis  with  filex  is  ftronger  than  that  of  the 
•carbonate  of  pot-afh  ;  in  confequence  of  which,  the  vitrification 
it  produces  is  more  quick  jmd  eafy. 

Lime  and  the  acids  decompofe  it,  with  the  fame  phenomena 
which  wie  have  obferyed  at  the  article  carbonate  of  Pot-afh. 

ARTICLE     m. 

Carbonate  of  Ammoniack. 

This  fait  has  been  generally  known  by  the  name  of  Concrete 
Volatile  Alkali.  It  has  likewife  been  diftinguifhed  by  that  of 
Cretaceous  Volatile  Alkali,  &c. 

It  may  be  obtained  by  diftillation  from  many  animal  fubftan- 
ces.  Tobacco  affords,  likewife,  a  large  proportion  ;  but  almoft: 
the  whole  of  that  which  is  employed  in  the  arts,  and  in  medi- 
cine, is  formed  by  the  diredt  combination  of  the  carbonick  acid 
jind  ammoniack,  or  volatile  alkali.     This  combination  may  b« 


J  4©  TroduEilon  of  the  Sulphurick 

efFefled — i.  By  pafling  the  carbonick  acid  through  ammonlaclcj 
or  the  pure  volatile  alkali  in  folution.  2.  By  expofing  ammo- 
iiiack  in  an  atmofphere  of  carbonick  acid  gas.  3.  By  decom- 
pofing  the  muriate  of  aramoniack  by  the  neutral  falts  which  con- 
tain this  acid,  fuch  as  the  carbonate  of  lime  or  common  chalk. 
For  this  purpofe,  white  chalk  is  taken,  and  very  accurately  dri- 
ed ;  and  then  mixed  with  equal  parts  of  muriate  of  ammoniack 
or  common  fal  ammoniack,  in  fine  powder.  This  mixture  is 
put  into  a  retort,  and  diftilled  ;  the  ammoniack  and  the  carbon- 
ick acid  being  diftngaged  from  their  bafes,  and  reduced  into 
▼apours,  combin'^  together,  and  are  depofited  on  the  fides  of 
the  receiver,  where  they  form  a  ftratum  more  or  lefs  thick. 

The  cryftallization  of  this  carbonate  appeared  to  me  to  be 
that  of  a  four-fided  prifm,  terminated  by  a  dihedral  fummit. 

The  carbonate  has  lefs  fmell  than  the  ammoniack  ;  it  is  very 
foluble  in  water.  Cold  water  diiTolves  itsown  weight  of  this 
("alt,  at  the  temperature  of  fixty  degrees  of  Fahrenheit. 

One  hundred  grains  of  this  fait  contain  forty-five  parts  acid, 
forty-three  alkali,  and  twelve  water,  according  to  Bergmann, 

Moil  acids  decompofe  it,  and  difplace  the  carbonick  acid. 


CHAPTER    II. 

Concerning  the  Sulplmrick  Acid. 

SULPHUR,  like  every  other  combuftible  fubflance,  cannot 
tc  burnt  but  by  virtue  of  the  oxigenous  gas  which  combines 
•with  it. 

The  moft  ufual  phenomena  which  accompany  this  combull- 
ion  are,  a  blue  flame,  a  whitifh  and  fuftbcating  vapour,  and  a 
ftrong,  penetrating,  and  difagreeable  fmell. 

The  refults  of  this  combination  vary  according  to  the  pro- 
portion in  which  thefe  two  principles  enter  into  this  fame  com- 
bination. 

The  fulphureous  or  the  fulphurick  acid  may  be  at  pleafurc 
obtained  from  fublimed  fulphur,  or  from  crude  fulphur,  ac- 
cordingly as  a  greater  or  lefs  quantity  of  oxigene  is  combined 
with  the  fulphur,  by  means  of  combuftlon. 

When  the  current  of  air  which  maintains  the  combuft:ion  is, 
rapid,  the  fulphur  is  carried,  and  depofited  without  any  appar- 
ent alteration,  into  the  internal  part  of  the  leaden  chambers  in 
which  the  oil  of  vitriol  is  made.  If  the  current  of  air  be  ren- 
dered more  moderate,  the  combination  is  fomewhat  more  ac- 
curate •,  the  fulphur  is  partly  changed,  and  is  depofited  in  a 
pellicle  upon  the  furface  of  the  w^ter.     This  pellicle  is  flexible 


or  Viiriolich  jic'id.  14I 

ijke  a  (kin,  and  may  be  handled  and  turned  over  in  the  fame 
manner.  If  tlie  current  be  ilill  lefs  rapid,  and  the  air  be  fuf- 
fered  to  have  a  fufficient  time  to  form  an  accurate  combination 
with  the  fulphur,  the  refuit  is  fulphureous  acid  ;  which  acid 
preferves  its  gafeous  form  at  the  temperature  of  the  atmofphere, 
and  may  become  hquid  Uke  water  by  the  application  of  cold, 
according  to  the  fine  experiments  of  Mr.  Monge.  If  the  com- 
bullion  be  (till  flower,  and  the  air  be  fufFered  to  digeft  upon  the 
fulphur  a  longer  time  and  with  greater  accuracy,  the  refuit  is 
fulphurick  acid  :  this  lafl  combination  may  be  facilitated  by  the 
piixture  of  faltpctre  becaufe  this  fubftance  furnillies  oxigene 
very  abundantly. 

Numerous  experiments  which  I  have  made  in  my  manufactory, 
to  economize  the  faltpetre  employed  in  the  fabrication  of  oil  of 
vitriol,  have  feveral  tim.es  exhibited  the  refults  here  mentioned. 

All  the  procefles  which  are  capable  of  being  adapted  for  ex- 
Cradling  the  fulphurick  acid,  are  reducible  to — i.  The  extrac- 
tion of  it  from  fubilances  which  contain  it.  2.  Its  diredl  for- 
mation by  the  combination  of  fulphur  and  oxigene. 

In  the  firft  cafe,  the  fulphures,  or  vitriolick  falts  of  Iron,  cop-, 
per,  or  zinc,  and  even  thofe  whofe  bafes  are  clay  and  lime,  ac- 
cording to  Newman  and  Margraff,  may  be  expofed  to  diflilla- 
tion.  But  thefe  expenfive  proceffes  are  not  very  eafy  to  be 
carried  into  execution  ;  and  accordingly  they  have  been  aban- 
doned, to  make  room  for  others  of  greater  fimplicity. 

In  the  fecond  cafe,  the  oxigene  may  be  prefented  to  the  ful- 
phur in  two  forms  ;  either  in  the  ftate  of  gas,  or  in  the  con- 
crete ftate. 

I.  The  combuftion  of  fulphur  by  oxigenous  gas,  is  perform- 
ed in  large  chambers  lined  v/ith  lead.  The  combuftion  Is  fa- 
cilitated by  mixing  about  one  eighth  of  a  nitrate  of  pot-afli 
with  the  fulphur.  The  acid  vapours  which  fill  the  chamber 
are  precipitated  againft  its  fides,  and  the  condenfation  is  facil- 
itated by  a  itratum  of  water  difpofed  on  the  bottom  of  the 
chamber.  In  fome  manufactories  in  Holland,  this  combuftion 
is  performed  in  large  glafs  balloons  with  large  mouths,  and 
the  vapours  are  precipitated  upon  water  placed  at  the  bottom. 

In  both  cafes,  wJhen  the  water  Is  fufEciently  impregnated 
with  acid,  it  Is  concentrated  In  leaden  boilers,  and  rectified  in 
glafs  retorts,  to  render  it  white,  and  to  concentrate  it  fufhclent- 
ly  for  the  purpofes  of  trade.  The  acid,  when  of  a  due  ftrength, 
indicates  fixty-fix  degrees,  according  to  the  aerometer  of  Mr. 
l^aume  ;  and  when  it  has  not  been  carried  to  this  degree,  it  is 
unfit  for  moft  of  the  ufes  for  which  it  is  intended.  It  cannot, 
for  example,  be  employed   in  diJlblvinj;  indigo  5  for  the  fmaU 


f  4«  Neuirat  and   Congealed  Sulphnnck  Add, 

quantity  of  nitrick  acid  which  it  contains,  unites  with  the  blue 
of  the  indigo,  and  forms  a  green  colour.  I  have  afcertained 
this  phenomenon  by  very  accurate  experiments  ;  and  I  have 
teen  a  witnefs  to  the  failing  of  colours,  and  the  lofs  of  fluffs, 
in    confequence  of  the  imperfe6lion  of  the  acid. 

2.  When  t]ie  oxigene  in  the  concrete  ftate  is  prefented  to 
the  fulphur,  it  is  then  in  combination  with  other  bodies,  which  it 
abandons  to  unite  with  this  laft.  This  happens  when  the  ni- 
trick acid  is  diltilled  from  fulphur.  Forty-eight  ounces  of  this 
acid,  at  thirty-fix  degrees,  diftilled  from  two  ounces  of  fulphur, 
afforded  near  four  ounces  of  good  fulphurick  acid.  This  fad 
nvas  known  to  Matte  Lafaveur  :  but  1  pointed  out  all  the  phe- 
nomena and  circumftances  of  the  operation  in  1781. 

Sulphur  may  likewife  be  converted  into  fulphurick  acid  by 
means  of  the  oxigenated  muriatick  acid. — Encyclopedie  Metho- 
dique,  torn.  i.  p.  370. 

The  fulphurick  acid  which  is  found  difengaged  in  fome  place* 
in  Italy,  appears  likewife  to  arife  from  the  combuftion  of  ful- 
phur. Baldaffari  has  obferved  it  in  this  ftate  in  a  hollow  grotto, 
in  the  midft  of  a  mafs  of  incrufcations  depofited  by  the  baths  of 
Saint  Philip,  in  Tufcany.  He  ajTerts  that  a  fulphureous  vapour 
continually  arifes  in  this  grotto.  He  likewife  found  fulphure- 
ous and  vitriolick  effervefences  at  St.  Albino,  near  mount  Pulci- 
ano,  and  at  the  lakes  of  Travale,  where  he  obferved  the  branch- 
;es  of  a  tree  covered  with  concretions  of  fulphur  and  the  oil  of 
Titriol. — Journal  dePhyflque,  t.  vii.  p.  395. 

O.  Vandelli  relates  that,  in  the  environs  (^  Sienna  and  Viter- 
bo,  fulphurick  acid  is  fometimes  found  diffolved  in  water.  Mr. 
(the  commander) De  Dolomeu  affirms  that  he  found  it  pure  and 
cryftallized  in  a  grotto  of  mount  Etna,  from  which  fulphur  was 
formerly  obtained. 

According  to  a  firfl  experiment  of  Mr.  Berthollet,  fixty-ninft 
parts  of  fulphur  with  thirty-one  parts  of  oxigene  formed  on€ 
hundred  parts  of  fulphurick  acid  ;  and  according  to  a  fecond 
experiment,  feventy-two  of  fulphur  and  twenty-eight  of  oxigene 
formed  one  hundred  parts  of  dry  acid. 

The  various  degrees  of  concentration  of  the  fulphurick  acid 
have  caufed  it  to  he  dillinguifhed  by  different  names,  under 
which  it  is  known  in  commerce.  Hence  the  denominations  of 
Spirit  of  Vitriol,  Oil  of  Vitriol,  and  Glacial  Oil  of  Vitriol,  to 
exprefs  its  degrees  of  concentration. 

The  fulphurick  acid  is  capable  of  paffing  to  the  concrete  (late 
by  the  impreffion  of  intenfe  cold.  This  congelation  is  a  phe- 
nomenon long  fnice  known.  Cunckle  and  Bohn  have  fpoken  of 
it  ;  and  Boerhaa\e  fays,  exprefsly,  *«  Oleum  vitrioli,  fummarte 


CharaSlers  of  Sulphur ick  AciJ,  l^j 

purlffimum,  fummo  frigore  hiberno  in  glebas  folidefcit  perfpicu* 
as  ;  fed,  ftatim  ac  acuties  frigoris  letunditor,  liquefcit  et  dif- 
fluit." — We  are  indebted  to  the  Duke  D'Ayen  for  fome  very- 
valuable  experiments  upon  the  congelation  of  this  acid  ;  and 
Mr.  De  Morveau  repeated  them  vi'ith  equal  fuccefs  in  1782,  and 
proved  that  this  congelation  may  be  effected  at  a  degree  of  cold 
eonfiderably  lefs  than  what  had  been  mentioned.* 

I  have  already  feveral  times  obtained  beautiful  cryftals  of  ful- 
phurick  acid  in  flattened  hexahedral  prifms,  terminated  by  an 
hcxahedral  pyramid  j  and  my  experiments  have  enabled  me  to 
conclude — ^i.  That  the  very  concentrated  acid  cryltallizes  more 
difficultly  than  that  whofe  denlity  lies  between  (ixty-thre*  and 
fixty-five.  2.  That  the  proper  degree  of  cold  is  from  i  to  3 
degrees  below  o  of  Reaumur.  The  detail  of  my  experiments 
may  be  feen  in  the  volume  of  th^  Academy  of  Sciences  of  Pari* 
for  the  year  1784. 

The  characters  of  the  fulphurlck  acid  are  the  following  : 

1.  It  is  un£luous  and  fat  to  the  touch,  which  has  occafioned 
it  to  obtain  the  very  improper  name  of  Oil  of  Vitriol. 

2.  It  weighs  one  ounce  and  feven  gros  in  a  bottle  containing 
one  ounce  of  diftilled  water. 

3.  It  produces  heat,  when  mixed  with  water,  to  fuch  a  de- 
gree as  to  exceed  that  of  boiling  water.  If  one  end  of  a  tube  of 
glafs  be  clofed,  and  water  poured  into  it,  and  the  clofed  end  of 
this  tube  be  plunged  into  water,  the  water  in  the  tube  may  be 
made  to  boil  by  pouring  fulphuriek  acid  into  the  external  water 
which  furrounds  the  tube. 

4.  It  leizes  with  great  avidity  all  inflammable  fubftances  j 
and  it  is  blackened  and  decompofed  by  this  combination. 

Stahl  fuppofed  the  fulpliurick  acid  to  be  the  univerfal  acid. 
He  founded  this  opinion  more  ctpecially  upon  the  circumllance, 
that  cloths  ibaked  in  a  folution  of  alkali  and  expofed  to  the  aiiv 
utrad^cd  an  acid  which  combined  with  the  alkali  ;  and  formed 
A  neutral  fait,  by  him  fuppofed  to  be  of  the  nature  of  fulphate  of 
pot-afh,  or  vitriolated  tartar.  Subfequent  and  more  accurate 
cxperimt^Us  have  (hewn  that  this  aerial  acid  was  the  carbonick  5 
ind  the  prefeut  ftate  of  our  knowledge  is  fuch  as  permits  uj» 
-lill  lefs  than  ever  to  believe  in  the  exiltcnce  of  an  univerfal  ucuL 


"  Sec"  alfo  the  experiments  of  Mr.    Ivier»  and    tlic  fate  expcrimenr*  oft  Mr„ 
"Cri^vcxiUini  mi  the  congelation  of  ;i(;ul»,  iu  the  Phllofuphlcal  Traaiaaioiw, 


144  Sulphate  of  Soda. 

ARTICLE  T. 

Sulphate  of  Pot-afli. 

The  fulphate  of  pot-afh  is  defcrlbed  indlfFerently  under  the 
names  of  Arcanum  DupHcatum,  Sal  de  Duobus,  Vitriolated 
Tartar,  Vitriol  of  Pot-afh,  &c. 

This  fait  cry  ft  alii  zes  in  hexahedral  prifms,  terminating  in 
hexahedral  pyramids,  with  triangular  faces. 

It  has  a  lively  and  penetrating  tafte,  and  melts  difficultly  in 
the  mouth. 

It  depreciates  on  hot  coals,  becomes  red-hot  before  it  fufes, 
and  is  volatilized  u^ithout  decompofition. 

It  is  foluble  in  fixteen  parts  of  cold  vi^ater,  at  the  tempera- 
ture of  60  degrees  of  Fahrenheit :  and  boiling  water  diflblves 
one  fifth  of  its  weight. 

100  grains  contain  30,21  acid,  64,61  alkali,  and  5,18  water. 
Moft  of  the  fulphate  of  pot-afh  ufed  in  Medicine  is  formed  by 
the  dirc(Sl  combination  of  the  fulphurick  acid  and  pot-afli,  or 
the  vegetable  alkali  :  but  that  which  is  met  with  in  commerce 
is  produced  in  the  diflillation  of  aqua  fortis,  by  the  fulphurick 
-acid  ;  this  has  the  form  of  beautiful  cryftals,  and  is  fold  in  the 
Comtat  Venaifin  at  forty  or  fifty  livres  the  quintal.  The  anal- 
yfis  of  tobacco  has  likewife  afforded  me  this  fulphate. 

Mr.  Baume  proved  to  the  Academy  in  1760,  that  the  nitrick 
acid,  alFifted  by  heat,  is  capable  of  decompofing  the  fulphate  of 
pot-afh.  Mr.  Cornette  afterwards  fhewed  that  the  muriatick 
acid  poffeffes  the  fame  virtue  ;  and  I  fhewed  in  1780,  that  this 
acid  may  be  difplaced  by  the  nitrick  acid,  without  the  affiitance 
of  heat  ;  though  the  fulphurick  acid  refumes  its  place  when  the 
folution  is  concentrated  by  heat. 


ARTICLE   II. 

Sulphate  of  Soda. 

This  combination  of  the  fulphurick  acid  and  foda  is  ftill 
Icnovv'n  under  the  names  of  Glauber's  Salt,  Sr.l  Admirabile, 
Vitriol  of  Soda,  &c.  This  fait  cryflallizes  in  rectangular  o6la- 
hedrons,  of  a  prifmatick  or  cuneiform  figure,  of  which  the  two 
pyramids  are  truncated  near  their  balls. 

It  has  a  very  bitter  tafte,  and   eafily  diffolves  in  the  mouth. 

It  f wells  up  upon  heated  coals,  and  boils,  in  confequence  of  the 
diHipation  of  its  water  of  crvftallization.     After  this  water  has 


^H  Sulphate  of  Ammonlack.  24- 

been  difperfed,  there  remains  only  a  white  powder,  difficult  of 
fufion,  which  is  volatilized  without  decompofition  by  a  ftrong 
heat. 

By  expofure  to  the  air,  it  efFervefces,  lofes  its  tranfparency, 
and  is  reduced  to  a  fine  powder. 

Three  parts  of  water  at  60  degrees  of  Fahrenheit's  thermom- 
eter, difTolved  one  part  of  this  fait ;  but  boiling  water  diflblves 
its  own  weight. 

100  grains  of  fulphate  of  foda  contain  14  acid,  22  alkali  and 
64  water. 

It  is  formed  by  the  dlre£l:  combination  of  the  two  principles 
which  contain  it ;  but  the  tamarix  gallica,  which  grows  on  the 
fea  coafts,  contains  fo  large  a  quantity,  that  it  may  be  extracted 
to  advantage.  Nothing  more  is  neceifary  for  this  purpofe,  than 
to  burn  the  plant,  and  lixiviate  the  aflies.  That  fait  which  is 
fold  in  the  fouth  of  France,  in  fine  cryftals,  is  prepared  in  this 
manner.  It  is  very  pure,  and  the  price  does  not  exceed  thirty 
or  thirty-five  livres  the  quintal.  This  fulphate  is  likewife  form- 
ed in  our  laboratories  when  we  decompose  the  muriate  of  foda, 
or  common  fait,  by  the  fulphurick  acid. 

Pot-a(h  diflblved  by  heat  in  a  folution  of  fulphate  of  foda, 
precipitates  the  foda,  and  takes  its  place.  See  my  Chemical 
Memoirs. 


ARTICLE   m. 

Sulphate  of  Ammoniack. 

The  fulphate  of  Ammoniack,  commonly  known  by  the  name 
of  Glauber's  Secret  Ammoniacal  Salt ,  is  very  bitter. 

It  cryftallizes  in  long  flattened  prifms  with  fix  fides,  termi- 
nated by  fix-fided  pyram  ids. 

It  cannot  be  obtained  in  well-formed  cryftals  but  by  infenfi- 
ble  evaporation. 

It  ilightly  attracts  the  humidity  of  the  air 

It  liquefies  by  a  gentle  heat,  and  riles  over  a  moderate  fire. 

Two  parts  of  cold  water  diflblve  one  of  this  fait;  and  boiling 
water  diflblves  its  own  weight,  according  to  Fourcroy;  The 
fixed  alkalis,  barytes,  and  lime,  difcngage  the  ammoniack 
from  it. 

The  nitrick  and  muriatick  acids  difengage  the  fulphurick  acid. 

The  different  fubftances  of  which  we  have  treated  are  of  con- 
fideruble  ufe  in  the  arts  and  medicine. 
T 


I4<5  Acid  tf  Nitre,  or  Mi  rick  Add, 

The  fulphureous  acid  is  employed  in  whitening  filk,  and.  giv- 
ing it  a  degree  of  Juftre.  Stahl  had  even  combined  it  with  al- 
kali, and  formed  the  fait  fo  well  known  under  the  name  of 
Stahl's  Sulphureous  Salt.  This  combination  paflTes  quickly  tO' 
the  ftate  of  fulphate,  if  it  be  left  expofed  to  the  air ;  as  it  fpee- 
dily  abforbs  the  oxigene  which  is  wanting  for  that  purpofe. 

The  principal  ufe  of  the  fulphurick  acid  is  in  dying,  in  which 
art  it  ferves  to  diflblve  indigo,  and  carry  it  in  a  ftate  of  extreme 
divifion  upon  the  (tuffs  to  be  died  ;  it  is  likewife  ufed  by  the 
manufacturers  of  Indiens,  or  filk  and  fluff  mixtures,  to  carry  off 
the  preparation  of  thefe  goods,  wherein  lime  is  ufed.  The 
chemift  makes  great  ufe  of  this  acid  in  his  analyfes  ;  and  to- 
feparate  other  acids  from  their  combination,  fuch  as  the  carbon- 
ick,  the  nitrick,  and  the  muriatick  acids. 

The  fulphate  of  pot-afli  is  known  in  medicine  as  an  altera- 
tive, and  is  ufed  in  cafes  of  la£teous  coagulations.  It  is  given 
in  the  dofe  of  a  few  grains,  and  is  even  purgative  in  a  greater 
dofe. 

The  fulphate  of  foda  Is  an  effe<flual  purgative  in  the  dofe  of 
from  four  to  eight  gros,  or  drams.  For  this  purpofe  it  is  dif-^ 
folved  in  a  pint  of  water. 


CHAPTER  III. 

Concerning  the  Nitrick  Acid. 

THE  nitrick  acid,  called  Aqua  Fortis  in  commerce,  is  lighter 
than  the  fulphurick.  It  ufually  has  a  yellow  colour,  a  Itrong 
and  difagroeable  fmell,  and  emits  red  vapours.  It  gives  a  yel- 
low colour  to  the  flcln,  to  filk,  and  toalmofl:  all  animal  fubftan- 
ces  with  which  it  may  come  in  contadb  It  diffolves  and  fpeed- 
ily  corrodes  iron,  copper,  zinc,  &c.  with  the  efcape  of  a  cloud 
of  red  vapours  during  the  whole  time  its  adion  lafts.  It  entire- 
ly deftroys  the  colour  of  violets,  which  it  reddens.  It  unites 
to  water  with  facility  ;  and  the  mixture  affumes  a  green  colour, 
which  difappears  when  ftill  further  diluted. 

This  acid  has  been  no  where  found  in  a  difengaged  flate.  It 
always  exifts  in  a  ftate  of  combination  ;  and  it  is  from  thef? 
combinations  that  the  art  of  chemiftry  extradls  it,  to  apply  to 
our  ufes.  The  nitrick  of  pot-alh,  or  common  nitre,  is  the  com- 
bination which  is  beft  known,  and  is  likewife  that  from  which' 
we  ufually  extraiH;  the  nitrick  acid^ 


jicid  of  Nitre y  cr  Niirick  Acid.  147 

The  procefs  ufed  in  commerce  to  make  aqua  fortis,  confids 

mixing  one  part  of  faltpetre  with  two  or  three  parts  of  red 
Duiar  earth.  This  mixture  is  put  into  coated  retorts,  difpofed  in 
a  galkry  or  long  furnace,  to  each  of  which  is  adapted  a  receiver. 
The  firlt  vapour  which  arifes  in  the  diftillation  is  nothing  but 
water,  which  is  futFered  to  efcape  at  the  place  of  jurifture,  be- 
fore the  luting  :  and  when  the  red  vapours  begin  to  appear,  the 
phlegm  which  is  condenfed  in  the  receiver  is  poured  out  •,  and 
the  receiver,  being  replaced,  is  carefully  luted  to  the  neck  of  the 
retoit.  The  vapours  which  are  condenfed,  form  at  firft  a 
greenifh  liquor  :  this  colour  difappears  infenfibly,  and  is  replac- 
ed by  another  which  is  more  or  lefs  yellow.  Some  chemifts, 
more  efpecially  Mr.  Baume,  were  of  opinion  that  the  earth  a£l:- 
.ed  upon  the  faltpetre  by  virtue  of  the  fulphurick  acid  it  contains. 
But  not  to  mention  that  this  principle  does  not  exill  in  all  the 
earths  made  ufe  of,  as  Meffrs.  Macquer,  De  Morveau,  and 
Scheele  have  proved,  we  know  that  pulverized  flints  equally 
produce  the  decompofition  of  faltpetre.  I  am  therefore  of 
opinion  that  the  effect  of  thefe  earths  upon  the  fait  ought  to  be 
leferred  to  the  very  evident  affinity  of  the  alkali  to  the  filex, 
which  is  a  principal  component  part.;  and  more  efpecially  to 
the  flight  degree  of  adheflon  which  exifls  between  the  conftit- 
\jent  principles  of  nitrate  of  pot-afli. 

We  decompofe  faltpetre  in  our  laboratories  by  means  of  the 
fulphurick  acid.  Very  pure  nitrate  of  pot-afh  is  taken,  and  in- 
troduced into  a  tubulated  retort,  placed  in  a  fand  bath,  with  a 
jeceiver  adapted.  All  the  places  of  jun£fion  are  carefully 
Juted  ;  and  as  much  fulphurick  acid  as  amounts  to  half  the 
weight  of  the  fait  is  poured  through  the  tubulure  ;  and  the  dif- 
tillation is  proceeded  upon.  Care  is  taken  to  fit  a  tube  into 
the  tubulure  of  the  receiver ;  the  other  end  of  which  is  plun- 
ged into  water,  to  condenfe  the  vapours,  and  to  remove  all  fear 
of  an  explofion. 

Inflead  of  employing  the  fulphurick  acid,  we  may  fubflltute 
the  fulphate  of  iron,  and  mix  it  with  faltpetre  in  equal  parts. 
In  this  cafe,  the  refidue  of  the  diftillation,  when  well  waflied, 
forms  the  mild  earth  of  vitriol  made  ufe  of  to  polifli  glafs. 

iStahl  and  Kunckel  have  fpoken  of  a  very  penetrating  aqua 
fortis,  of  a  blue  colour,  obtained  by  the  diftillation  of  nitre  with 
arfenick. 

Whatever  precaution  is  taken  in  the  purification  of  the  falt- 
^  tie,  and  however  great  the  attention  may  be  whicli  is  bellow- 
ed upon  its  diftillation,  the  nitrick  acid  is  always  impregnated 
with  fome  foreign  acid,  either  the  fulphurick  or  niuriatick,  from 
which  it  requires  to  be  purified.     It  is  cleared  of  the  firft  by  re- 


14B  Properties  and  Component 

diftilling  It  upon  very  pure  faltpetre,  which  retains  the  fmall 
quantity  of  fulphurick  acid  that  may  exiil  in  the  mixture.  It  h: 
deprived  of  the  fecond  by  pouring  into  it  a  few  drops  of  a  folu- 
tion  of  nitrate  of  filver.  The  muriatick  acid  combines  ^with 
the  fih'er,  and  is  precipitated  with  it  in  the  form  of  an  infolu- 
ble  fait.  The  fluid  is  then  fufFered  to  remain  at  reft,  and  is 
afterwards  decanted  from  the  precipitate  or  depofition.  This 
acid,  fo  purified,  is  known  under  the  name  of  Aqua  Fortia  for 
Parting,  Precipitated  Nitrous  Acid,  Pure  Nitrick  Acid,  &c. 

Stahl  had  confidered  the  nitrick  acid  as  a  modification  of  the 
fulphurick,  produced  by  its  combination  with  an  inflammable 
principle.  This  opinion  has  been  fupported  by  feverai  new 
fadls,  in  a  diflertation  of  Mr.  Pietfli,  crowned  by  the  Academy 
of  Berlin  in  1749. 

The  experiments  of  the  celebrated  Hales  led  him  fl:ill  nearer 
to  this  conclufion,  as  his  manipulations  were  fucceflively  em- 
ployed upon  the  two  conftituent  principles  of  the  nitrick  acid. 
This  celebrated  philofopher  had  obtained  ninety  cubick  inches 
of  air  from  half  a  cubick  inch  of  nitre  ;  and  he  proceeded  ncn 
further  in  his  conclufions,  than  to  aflert  that  this  air  is  the  print 
cipal  caufe  of  the  explofions  of  nitre. 

The  fame  philofopher  relates  that  the  pyrites  of  Walton 
treated  with  equal  quantities  the  fpirt  of  nitre  and  water,  pro- 
duce an  air,  which  has  the  property  of  abforbing  the  frelh  air 
which  may  be  made  to  enter  the  velfel.  This  great  man  there-* 
fore  extraded  fuccellively  the  two  principles  of  the  nitrick  acid  ; 
and  thefe  capital  experiments  put  Dr.  Prieftley  in  the  road  to 
the  difcoveries  he  has  fince  made. 

It  was  not  however  until  the  year  1776,  that  the  analyfis  of 
the  nitrick  acid  was  well  known,  Mr.  Lavoifier,  by  diltilling 
this  acid  from  mercury,  and  receiving  the  feverai  produ(iis  in 
the  pneumato-chemical  apparatus,  has  proved  that  the  nitrick 
acid,  whofe  fpecifick  gravity  is  to  that  of  diililled  water  as 
131607  to  looooo,  contains — •■ 

oz.  gros.  grains. 

Nitrous  gas  1  7  5 1 1^ 

Oxigenous  gas      i  7  7I 

Water  13  —  — 

By  combing  thefe  three  principles  together  the  decompofcd 
acid  was  regenerated. 

The  action  of  the  nitrick  acid  on  moft  inflammable  matters, 
confifts  in  nothing  more  than  a  continual  decompofition  of  this 
acid. 

If  the  nitrick  acid  be  poured  upon  iron,  copper,  or  zinc,  thefe 
niaals  are  inftantly  attacked  with  a  ftrong  eifervefeuce  ;  and  a 


parts  of  Nit  rick  Acid,  1 49 

confiderable  difengagement  of  vapours  takes  place,  which  be- 
come  of  a  red  colour  by  their  combination  with  the  atmofpher- 
ick  air,  but  which  may  be  retained  and  collected  in  a  (late  of 
gas  in  the  hydro-pneumacick  apparatus.  In  all  thefe  cafes  the 
metals  are  ftrongly  oxided. 

The  nitrick  acid,  when  mixed  with  oils,  renders  them  thick 
and  black,  converts  them  into  charcoal,  or  inflames  them,  ac- 
cordingly as  the  acid  is  more  or  iefs  concentrated,  or  in  a  great- 
er or  Iefs  quantity. 

If  very  concentrated  nitrick  acid  be  put  into  an  apothecary's 
phial,  and  be  poured  upon  charcoal  in  an   impalpable  powder, 
,and  very  dry,  it  fets  it  on  fire  inltantly,  at  the   fame  time  that 
'carbonick  acid  and  nitrogene  gas  are  difengaged. 

The  various  acids  which  are  obtained  by  the  digeftion  of  the 
nitrick  acid  on  certain  fubftances,  fuch  as  the  oxalick  acid,  or 
acid  of  fugar,  the  arfenical  acid,  &c.  owe  their  exiftence  merely 
to  the  decompofition  of  the  nitrick  acid,  the  oxigene  of  which 
is  fixed  in  combination  with  the  bodies  upon  which  the  acid  is 
diililled.  The  facility  with  which  this  acid  is  decompofed, 
renders  it  one  of  the  moft  active  becaufe  the  a£lion  of  acids 
upon  moft  bodies  is  a  confequence  of  their  own  proper  decom- 
pofition. 

The  charaOers  of  nitrous  gas,  which  is  extracted  by  the  de- 
compofition of  the  acid,  are — i.  It  is  invifible,  or  perfedlly 
tranfparent.  2.  Its  fpecifick  gravity  is  rather  Iefs  than  that  of 
atmofpherical  air.  3.  It  is  unfit  for  refpiration,  though  the  ab- 
be Fontana  pretends  that  he  refpired  it  without  danger.  4.  It 
does  not  maintain  combullion.  5.  It  is  not  acid,  according  to 
the  experiments  of  the  Duke  de  Chaulnes.  6.  It  combines  with 
oxigene,  and  reproduces  the  nitrick  acid. 

But  what  is  the  nature  of  this  nitrous  gas  ?  It  was  at  firft 
pretended  that  it  confifts  of  the  nitrick  acid  faturated  withphlo- 
gillon.  This  fyftem  ought  to  have  been  abandoned  asfoonas 
it  was  proved  t^^nt  the  nitrick  acid  depofited  its  oxigene  upon 
the  bodies  on  wUivh  it  afted  ;  and  that  the  nitrous  gas  was  Iefs 
in  weight  than  the  acid  made  iife  of.  A  capital  experiment  of 
Mr.  Cavendifii  has  thrown  the  greateft  light  on  the  fubjedl. 
This  chemill  having  introduced  into  a  tube  of  glafs  feven  parts  of 
oxigenous  gas  obtained  without  nitrous  acid,  and  three  parts  of 
nitrogene  gas  *,  or,  by  eftimating  thefe  quantities  in  weight,  ten 
parts  of  nitrogene  to  twenty-fix  of  oxigene — and  having  caufed 
the  ele^trick  fpark  to  pafs  through  this  mixture,  perceived  that 
its  volume  or  bulk  was  greatly  diminiflied,  and  fucceeded  in 
converting  it  into  nitrick  acid.  It  may  be  prefumed,  from  his 
experiment,  that  the  acid  is  a  combination  of  feven  parts  of  oxi- 


x^o  Praperiies  and  Component 

gene,  and  three  of  nitrogene.  Thefe  proportions  conftitute  the 
ordinary  nitrick  acid  j  but  when  a  portion  of  its  oxigene  is 
taken  away,  it  pafles  to  the  ftate  of  nitrous  gas  ;  fo  that  nitrous 
gas  ia  a  combination  of  nitrogene  gas,  with  a  fmall  quantity  of 
oxigene. 

Nitrous  gas  may  be  decompofed  by  expofing  it  to  a  folutioii 
of  the  fulphure  of  pot-afh,  or  hepar  ot  fulphur  :  the  oxigene  gas 
unites  to  the  fulphur,  and  forms  fulphurick  acid,  while  tlie  nitro- 
gene gas  remains  behind  in  a  ftate  of  purity. 

Nitrous  gas  may  hkewife  be  decompofed  by  means  of  py- 
rophorus,  which  burns  in  thia  air,  and  abforbs  the  oxigenous- 
^as. 

The  ele£lrick  fpark  has  Hkewife  the  property  of  decompofing 
nitrous  gas.  Mr.  Van  Marum  has  obferved  that  three  cubick 
inches  of  the  nitrous  gas  are  reduced  by  eledlricity  to  one  cubick 
inch  and  three  quarters  5  and  that  this  refidue  no  longer  pof- 
{c^qA  any  property  of  nitrous  gas.  Laftly,  according  to  the  ex- 
periments of  Mr.  Lavoifier,  one  hundred  grains  of  nitrous  g^is 
contain  thirty-two  parts  nitrogene,  and  lixty-eight  parts  oxi- 
gene :  according  to  the  fame  chemiit,  one  hundred  grains  of  ni- 
irick  acid  contain  feventy-nine  and  a  half  oxigene  and  twenty 
and  a  half  nitrogene  ;  and  this  is  the  reafon  why  nitrous  gai 
iliould  be  employed  in  a  lefs  portion  than  nitrogene  gas,  to  com- 
bine with  the  oxigene  gas,  and  form  the  nitrick  acid. 

Thefe  ideas  upon  the  compofition  of  the  nitrous  acid  appear 
to  be  confirmed  by  the  repeated  proofs  we  now  have  of  the  ne- 
cefTity  of  caufing  fubftances,  which  afford  much  nitrogene  gas, 
to  be  prefented  to  the  oxigene  gas,  in  order  to  obtain  nitrick 
acid. 

The  feveral  ftates  of  the  nitrick  acid  may  be  clearly  explain- 
ed acordiiig  to  this  theory  : — i.  The  fuming  nitrous  acid  is  that 
in  which  the  oxigene  does  not  exift  in  a  lulHcient  proportion  \ 
and  we  may  render  the  whirell  and  moft  faturated  nitrick  acid 
fuming  and  ruddy,  by  depriving  it  of  a  part  of  its  oxigene  by 
means  of  metals,  oils,  inflammable  fubilances,  &c.  or  even  by 
difengaging  the  oxigene  by  the  fimple  expofition  of  the  acid  to 
the  light  ot  the  fun,  according  to  the  valuable  experiments  of 
Mr.  Berthollet. 

The  property  which  nitrous  gas  poffeffes,  of  aoforbing  oxi- 
gene to  form  the  nitrick  acid,  has  caufed  it  to  be  employed  to 
determine  the  proportion  of  oxigene  in  the  compofition  which 
forms  our  atmofphere.  The  abhe  Fontana  has  coiillrudled  on 
thefe  principles,  un  ingenious  eudiometer,  the  delcription  and 
manner  of  ufing  which  may  be  feen  in  the  firlt  volume  of  Dr, 
Ingenhoufz's  Experiments  upon  Vegetables. 


Paris  (f  Nttrick  Acid,  t^t 

Mr.  Berthollet  has  very  juftly  obferved,  that  this  eudiometer 
s  inaccurate,  or  produ&ive  of  deception — i.  Becaufe  it  is- 
^lilTicult  to  obtain  nitrous  gas  condantly  formed  of  the  fame  pro- 
protions  of  nitrogene  gas  and  oxigene ;  for  they  vary,  not  only 
according  to  the  nature  of  the  fubftances  upon  which  the  ni- 
trick  acid  is  decompofed,  but  hkewife  accordingly  as  the  folu- 
tion  of  any  given  fubftance  by  the  acid  is  made  with  greater  or 
lefs  rapidity.  If  the  acid  be  decompofed  upon  a  volarile  oil,  noth- 
thing  but  nitrogene  gas  can  be  obtained  j  if  the  acid  acSl  upon 
iron,  and  it  be  much  concentrated,  nitrogene  gas  only  will  be 
obtained,  as  I  have  obferved,  &c.  2.  The  nitrick  acid  which 
is  formed  by  the  union  of  nitrous  gas  and  oxigene,  difToIves  a- 
greater  or  lefs  quantity  of  nitrous  gas,  according  to  the  temper- 
ature, the  quality  of  the  air  which  is  tried,  the  fize  of  the  eudi- 
ometer, &c.  fo  that  the  diminution  varies  in  proportion  to  the 
greater  or  lefs  quantity  of  nitrous  gas  obtained  by  the  nitrick 
acid  which  is  formed  :  confequently  the  diminution  ought  to 
be  greater  in  winter  than  in  fummer.  Sec. 

According  to  the  experiments  of  Mr.  Lavoifier,  four  parts  of 
oxigenous  gas  are  fufeient  to  faturate  feven  parts  and  one 
third  of  nitrous  gas  ;  whereas  it  is  found  that  ncar'y  fixtee» 
parts  of  atmofpherick  air  are  required  to  produce  the  fame  ef- 
fect :  whence  this  celebrated  chemifl  has  concluded,  that  the  air 
of  the  atmofphere  does  not  in  general  contain  more  than  one 
fourth  of  oxigenous  or  refpirable  gas.  Repeated  experiments 
at  Montpellier,  upon  the  fame  principle,  have  convinced  me 
that  twelve  or  thirteen  parts  of  atmofpherick  air  are  conftantly 
fufficient  to  faturate  feven  parts  and   one  third  of  nitrous  gas* 

Thefe  experiments  (hew,  to  a  certain  degree  of  accuracy,  the 
proportion  in  which  vital  air  exifts  in  the  air  which  we  refpire  j 
but  they  do  not  give  us  any  information  refpecling  the  noxious 
gafes,  which  when  mixed  with  the  atmofpherick  air,  alter  it, 
and  render  it  unwholefome.  This  obfervation  very  much  cur- 
tails the  ufe  of  this  inftrument. 

The  combination  of  the  oxigenous  and  nitrous  gafes  always 
leaves  an  aeriform  refidue,  which  Mr.  Lavoifier  eftimated  a£ 
about  one  thirty-fourth  of  the  whole  volume  :  it  arifes  from 
the  mixture  of  the  foreign  gafeous  fubftances,  which  more  or 
lefs  affe<^  the  purity  of  the  gafes  made  ufe  of. 


152  Nitrate  of  Pot^Afiy  or  Nitre, 


ARTICLE    I. 

Nitrate  of  Pot-afh. 

The  nitrlck  acid,  combined  with  pot-afh,  forms  the  fait  fo 
well  known  under  the  names  of  Nitre,  Saltpetre,  Nitre  of  pot- 
afti,  &c. 

This  neutral  fait  is  rarely  the  product  of  any  dire£l  combi- 
nation of  its  two  confhituent  parts.  It  is  found  ready  formed 
in  certain  places ;  and  in  this  manner  it  is  that  the  whole  of 
the  nitre  employed  in  the  arts  is  obtained.  4 

In  the  Indies,  it  efflorefes  on  the  furface  of  uncultivated 
grounds.  The  inhabitants  lixiviate  thefe  earths  with  water, 
which  they  afterwards  boil  and  cryftallize  in  earthen  pots. 
Mr.  Dombey  has  obferved  a  great  quantity  of  faltpetre  near 
Lima,  upon  earths  which  ferve  for  paflure,  and  which  produce 
only  graminerous  plants.  Mr.  Talbot  Dillon,  in  his  travels  in- 
to Spain,  relates  that  one  third  of  all  the  grounds,  and  in  the 
fouthern  parts  of  that  kingdom,  even  the  dull  of  the  roads,  con- 
tain falt-petre 

Salt-petre  is  extra£led  in  France  from  the  ruins  and  plafber  ol 
old  houfes. 

This  fait  exifts  ready  formed  in  vegetables,  fuch  as  parietaria 
and  buglofs,  &c.  and  one  of  my  pupils,  Mr.  Virenque,  has 
proved  that  it  is  produced  in  all  extrads  which  are  capable  of 
fermenting. 

The  fermentation  of  faltpetre  may  be  favoured,  by  caufi ng 
certain  circumftances  to  concur  which  are  of  advantage  to  its 
formation. 

In  the  North  of  Europe,  the  falt-petre  beds  are  formed  with 
lime,  alhes,  earth  of  uncultivated  grounds,  and  flraw,  which  are 
ftratified,  and  watered  with  urine,  dunghill-water,  and  mother 
waters.  Thefe  beds  are  defended  by  a  covering  of  heath  or 
broom.  In  the  year  1775,  ^^^  I^^"g  caufed  a  prize  to  be  pro- 
pofed  by  the  Royal  Academy  of  Sciences  at  Paris,  to  difcover 
a  method  of  increafing  the  produ61:  of  faltpetre  in  France,  and 
to  relieve  the  people  from  the  obligation  of  permitting  the  falt- 
petre makers  to  examine  their  cellars,  in  order  to  difcover  and 
carry  away  faltpetre  earths.  -  Several  Memoirs  were  offered  on 
the  fubjetl,  which  the  Academy  united  into  a  fingle  volume  ', 
and  thefe  have  added  to  our  knowledge,  by  inftrufting  us  more 
efpecially  concerning  the  nature  of  the  matters  which  favour  the 
formation  of  nitre.  It  was  known,  for  example,  long  fmce,  that 
nitre  is  formed  in  preference  near  habitations,  or  in  earths,  im- 


l^roduFtion  of  Nitre,  lj> 

iCgnatcd  with  animal  products  :  it  was  likewife  known  that, 
in  general,  the  alkaline  bafis  was  afforded  by  the  concurrence  of 
^  vegetable  fermentation.  Mr.  Thouvenel,  whofe  memoir  was 
crowned,  has  proved  that  the  gas  which  is  difengaged  by  putre- 
fadion,  is  neceffary  for  the  formation  of  nitre  ;  that  blood,  and 
pext  to  it,  urine,  were  the  animal  parts  which  were  the  mod  fa- 
vourable to  its  formation  ;  that  the  mod  minutely  divided  and 
the  lightefl;  earths  were  the  mod  proper  for  nitrification  ;  that 
the  current  of  air  muft  be  properly  managed,  to  fix  upon  thefc 
earths  the  nitrick  acid  which  is  formed,  &c. 

It  feems  to  me  that  Becher  poffeifed  a  confiderably  accurate 
knowledge  of  the  formation  of  nitre,  as  appears  from  the  follow- 
ing paflag^s  : 

"  Hsec  enim  (vermes,  mufcje,  ferpentes)  putrefa£l:a  in  terram 
"  abeunt  prorfus  nitrofam  ;  ex  qua  etiam  communi  modo  nitrutn 
"  copiofum  parari  poteft,  fola  elixatione  cum  aqua  communi."— 
"Phyf.  Subt.  lib.  i.  S.  V.  t.  i.  p.  286. 

<«  Sed  et  ipfum  nitrum  necdum  finis  ultimus  putrefa£tionis 
'**  efl ;  nam  cum  ejufdem  partes  igneae  feparantur,  relinqiise  in 
*«  terram  abeunt  prorfum  puram  &  infipidam,  fed  fmgulari 
«<  magnetifmo  praeditam  novum  fpiritum  aerum  attrahendi, 
«f  rurfufque  nitrum  fiendi." — Phyf  Subt.  S.  V.  t.  i.  p.  292. 

From  all  the  difcoveries  and  cbfervations  which  have  been 
hitherto  made,  it  follows  that,  in  order  to  eftablifh  artificial  nitre 
W6is,  it  is  neceffary  that  animal  putrefaction  and  vegetable  fer- 
mentation fhould  concur.  The  nitrogene  gas,  in  its  difengage- 
ment  from  the  animal  fubftances,  combines  with  the  oxigene, 
and  forms  the  acid,  which  again  unites  with  the  alkali,  whofe 
formation  is  favoured  by  the  vegetable  decompofition. 

When  the  manufa£lurer  is  in  poffefTion  of  faltpetre  grounds, 
whether  by  the  fimple  operations  of  nature  or  by  the  affiftanc« 
of  art,  the  faltpetre  is  extracted  by  the  lixiviation  of  thefe  earths  ^ 
which  lixivium  is  afterwards  concentrated,  and  made  to  cryftal- 
lize.  In  proportion  as  the  evaporation  goes  forward,  the  marine 
fait,  which  almod  always  accompanies  the  formation  of  nitre,  is 
precipitated.  This  is  taken  out  with  ladles,  and  fet  to  drain  in 
baflcets  placed  over  the  boilers. 

As  a  great  part  of  the  nitre  has  an  earthy  bafis,  and  requires 
to  be  furnifhed  with  an  alkaline  bafis  to  caufe  it  to  crydallize, 
this  purpofe  is  accomplifhed  either  by  mixing  alhes  with  the 
faltpetre  earths,  or  by  adding  an  alkali  ready  formed  to  the  lix- 
ivium itfelf. 

Nitre  obtained  by  this  fird  operation  is  never  pure,  but  con- 
tains fea-falt,  and  an  extra£live  and  colouring  principle,  frora 
which  it  mud  be  cleared.     For  this  purpofe  it   is  dilfolved  in 
U 


■ 


J 54  Compofition  of  Gunpowder. 

frefh  water,  which  is  evaporated,  and  to  ^A'hich  bullocVs  bloocf 
i-nay  be  added,  to  clarify  the  foliition.  The  nitre  obtained  by 
the  fecond  manipulation  is  known  by  the  name  of  Nitre  of  the 
Second  Boiling.  If  recourfe  be  had  to  a  third  operation  to  purify 
it,  it  is  then  called  Nitre  of  the  Third  Boiling. 

The  purified  nitrate  of  pot-afh  is  employed  in  delicate  opera- 
tions, fuch  as  the  manufacture  of  gunpowder,  the  preparation  of 
aqua  fortis  for  parting,  and  the  folution  of  mercury,  &c.  The 
faltpetre  of  the  firft  boiling  is  ufed  in  thofe  works  where  aqua 
fortis  is  made  for  the  diers.  It  affords  a  nitro-muriatick  acid^ 
which  is  capable  of  diffolving  tin  by  rtfeif. 

The  nitrate  of  pot-aili  cryilallizes  in  prifmatick  oCtahedronSy 
which  almofl  always  reprefent  fix-fided  flattened  prifms,  termi- 
nated by  dihedral  fummits. 

It  has  a  penetrating  talle  followed  by  a  fenfation  of  coldnef^. 

It  is  fufible  upon  ignited  coals  ;  and  in  this  cafe  its  acid  isde- 
compofed.  The  oxigene  unites  with  the  carbone  and  forms  the 
carbonick  acid  ;  the  nitrogene  gas  and  the  water  are  dilTipated  ^ 
and  it  is  this  mixture  of  principles  which  has  been  known  by 
the  name  of  Clyffus  of  Nitre. 

The  diftiliation  of  the  nitrate  of  pot-afli  affords  twelve  thou- 
fand  cubitk  inches  of  oxigenous  gas  for  each  pound  of  the  fait. 

Seven  parts  of  water  diflblve  (5ne  of  nitre,  at  fixty  degrees  of 
Fahrenheit  j  and  boiling  water  diffolves  its  own  weight  of  this 
fait. 

One  hundred  grains  of  the  cry  dais  of  nitre  contain  thirty  acid;, 
fixty-three  alkali,  and  feven  water. 

When  a  mixture  of  equal  parts  of  nitre  and  fulphur  ar 
thrown  into  a  red-hot  crucible,  a  faline  fubftance  is  obtained, 
which  was  formerly  called  Sal  Polychreft  of  Glafer,  and  which 
)vas  fince  been  coniidered  as  Sulphate  of  Pot-afli.  If  nitre  be 
fufed,  and  a  few  pinches  of  fulphur  be  thrown  upon  this  fait  in 
fuuon,  and  the  whole  be  afterwards  poured  out  or  caft  into  plates, 
it  forms  a  liilt  known  by  the  name  of  Cryllal  Mineral. 

A  mixture  of  feventy-fivd  parts  of  nitre,  nine  and  a  half  of 
fulphur,  and  fifteen  and  a  half  of  charcoal,  forms  gunpowder. 
This  mixture  is  triturated  from  ten  to  fifteen  hours,  care  being 
taken  to  moiften  it  from  time  to  time.  This  trituration  is  ufual- 
iy  performed  by  pounding  mills,  whofe  peftles  and  mortars  are 
of  wood.  In  order  to  give  the  powder  the  form  proper  to  gran- 
ulate it,  it  is  paffed  through  fieves  of  flcin,  whofe  perforations  ar^ 
of  various  lizes.  The  grained  powder  is  then  fifted,  to  fepara: 
the  duft,  and  it  is  afterwards  carried  to  the  drying-houfe.  Gup.- 
powder  for  artillery,  or  cannon-powder,  receives  no  other  pre- 
paration J  but  it  is  necJiTary  to  glaze  the  powder  which  is  Iv 


Fu!mi?iatM  Powder, 


■s$ 


.  jiided  for  fowling.  This  lad  preparation  is  efFe^flecl  by  putting 
it  into  a  kind  of  cafk  which  turns  on  an  axis,  and  by  whofe 
-^lovement  the  angles  of  the  grains  are  broken,  and  their  fur- 
ices  poliihed.  We  are  indebted  to  Mr.  Baume  and  the  cheva- 
iier  Darcy  for  a  fcries  of  experiments,  in  which  they  have 
proved — 
T    I .  That  good  gunpowder  cannot  be  made  without  fulphur. 

2.  That  charcoal  is  likewife  indifpenfably  neceflary. 

3.  That  the  quahty  of  gunpowder  depends,  c?eteris  paribus, 
fipon  the  accuracy  with  which  the  mixture  is  made. 

4.  That  the  efftCt  of  gunpow,der  is  greater  when  fimply  dried 
than  when  it  is  granulated. 

Tiic  eiTecl  of  gunpowder  depends  upon  the  rapid  decompoli- 
♦ion  which  is  made  in  an  inftant  of  a  confiderable  mafs  of  nitre, 
and  the  fuddcn  formation  of  thofe  gafes  which  are  the  immedi- 
ate produfl.  Bernoulli,  in  the  lall  century,  afcertained  the 
developemcnt  of  air  by  the  deflagration  of  gunpowder  :  he  plac- 
ed four  grains  of  powder  in  a  recurved  tube  of  glafs,  plunged 
the  tube  in  water,  and  fet  fire  to  the  gunpowder  by  means  of 
the  burning-glafs  ;  after  the  combudion  the  intcriour  air  occu- 
pied a  larger  fpaee,  fo  that  the  fpace  abandoned  by  the  water 
was  fuch  as  would  have  contained  two  hundred  grains  of  gun^ 
powder.-r~Hift.  de  TAcade'mie  dcs  Sciences  de  Paris,  i6p6,  t.  ii. 
Mcmoire  de  M.  Varignon  fur  le  Feu  et  la  Flamme. 

The  fulminating  powder,  which  is  made  bv  the  mixture  and 
trituration  of  three  parts  of  nitre,  two  of  fait  of  tartar,  and  one 
■of  fulphur,  produces  effedls  ftill  more  terrible.  In  order  to  ob- 
tain the  full  efFeft,  it  is  expofed  in  a  ladle  to  a  gentle  heat  j  the 
mixture  melts,  a  fulphureous  blue  flame  appears,  and  the  explo- 
fion  takes  place.  Care  mud  be  taken  to  give  neither  too  drong 
nor  too  flight  a  degree  of  heat.  In  either  cafe,  the  combudioii 
of  the  principles  takes  place  Separately,   and  without  explofion. 


ARTICLE    II. 

Nitrate  of  Soda. 

This  fidt  has  received  the  name  of  Cubick  Nitre  on  account 
of  its  form  ;  but  this  denomination  is  not  exacl:,  becaufe  it  af- 
tcts  a  figure  condantly  rhomboidal. 

It  has  a  cool,  bitter  tade. 

It  flightly  attracts  the  humidity  of  the  air. 

Cold  water,  at  fixty  degrees  of  Fahrenheit's  therm.ometer,  dif- 
folvcs  one  third  of  its  weight ;  and  hot  water  fcarcely  diflblves 
more. 


i^6  Muriatich  Acid, 

It  fufes  upon  burning  coals  with  a  yellow  colour  ;  whereag. 
common  nitre  affords  a  white  flame,  according  to  Margraft'— -^ 
24  Diflert.  fur  le  Sel  Commun,  t.  ii.  p.  343. 

100  grains  of  this  fait  contain  28.80  acid,  50.09  alkali,  and 
a  1. 1 1  water. 

It  is  almoft  always  the  product  of  art. 


ARTICLE  III. 

Nitrate  of  Amraoniack. 

The  vapours  of  ammoniack,  or  volatile  alkali,  being  brought 
into  contaft  with  thofe  of  the  nitrous  acid,  combine  with  them, 
and  form  a  white  and  thick  cloud,  which  flowly  fubfides. 

But  when  the  acid  is  diredlly  united  to  che  alkali,  the  refult 
is  a  fait,  which  has  a  cool,  bitter,  and  urinous  tafte, 

Mr.  De  Lille  pretends  that  it  cryllallizes  in  beautiful  needles, 
fimilar  to  thofe  of  fulphate  of  pot-afh. 

Thefe  cryftals  cannot  be  obtained  but  by  a  very  flow  evapo- 
ration. 

When  this  fait  is  expofed  to  the  fire,  it  liquefies,  emits  aque- 
ous vapours,  dries,  and  detonates. 

Mr.  BerthoUet  has  analyfed  all  the  refults  of  this  operation, 
and  has  drawn  from  them  a  new  proof  of  the  truth  of  the  prin« 
ciples  which  he  has  eftablifhed  with  regard  to  ammoniack. 


CHAPTER  IV. 

Concerning  the  Muriatick  Acid. 

THIS  acid  is  generally  known  by  the  name  of  Marine  Acid,^ 
and  it  is  ftill  diftinguiflied  among  artifans  by  the  name  of  Spirit 
of  Salt. 

It  is  lighter  than  the  two  preceding  acids  5  it  has  a  ftrong 
penetrating  fmell,  refembling  that  of  fafFron,  but  infinitely  more 
pungent ;  it  emits  white  vapours  when  it  is  concentrated  ;  it 
precipitates  filvcr  from  its  folution  in  the  form  of  an  infoluble 
fait,  &c.  This  acid  has  no  where  been  found  difengaged  j  and 
to  obtain  it  in  this  itate,  it  is  necelTary  to  difengage  it  from  it^ 
combinations.  Common  fait  is  ufually  employed  for  thi^ 
purpofe. 


D'l/iiUat'ion  of  Muriaticl  Acid,  157  ' 

The  fplrit  of  fait  of  commerce   is  obtained  by  a  procefs  little 
ifTering  from  that  which  is  uied  in  the    extraition  of  aqua  for- 
ds.    But  as  this  acid  adheres  more  Itrongly  to  itsbafis,  the  pro- 
du£l  is  very  weak,  and  only  part  of  the  marine  fait  is  decom- 
pofed. 

Flints  pulverized  and  mixed  with  this  fait,  do  not  feparate 
the  acid.  Ten  pounds  of  Hints  in  powder,  treated  by  a  violent 
fire  with  two  pounds  of  the  fait,  did  not  afford  me  any  other 
produft  than  a  mafs  of  the  colour  of  litharge.  The  fumes^ 
were  not  perceptibly  acid.  If  clay,  which  has  once  ferved  to 
decompofe  marine  fiilt,  be  mixed  with  a  new  quantity  of  the 
fame  fait,  it  will  not  decompofe  an  atom  of  it,  even  though  the 
mixture  be  moiftened  and  formed  into  a  pafte.  Thefe  experi- 
ments have  been  feveral  times  repeated  in  my  manufa£lory,  ancf 
have  conftantly  exhibited  the  fame  refults. 

The  fulphate  of  iron,  or  martial  vitriol,  which  fo  eafily  difen- 
cngages  the  nitrick  acid,  deccmpofes  marine  fait  5  but  very  im- 
perfettly.  • 

The  impure  foda  known  in  France  by  the  name  of  Blan- 
quette,and  in  which  my  analyfis  has  exhibited  twenty-one  pounds 
of  common  fait  out  of  tv/enty-five,  fcarcely  affords  any  muria- 
tick  acid  when  it  is  diftiiled  with  the  fulphurick  acid  ;  but  it  af- 
fords abundance  of  fulphureous  acid.  Mr.  Berard  diretlior  of 
my  manufactory  attributed  thefe  refults  to  the  coal  contained  in 
this  foda,  which  decompofed  the  fulphurick  acid.  He  there- 
fore calcined  the  blanquette  to  deftroy  the  charcoal  :  and  iheii 
he  found  he  could  treat  it  in  the  fame  manner  as  common  fait, 
and  with  the  fame  fuccefs. 

The  fulphurick  acid  is  ufually  employed  to  decompofe  ma- 
rine fait.  My  method  of  proceeding  confifls  in  drying  the  ma- 
rine fait,  pounding  it,  and  putting  it  into  a  tubulated  retort  placed, 
upon  a  fand  bath.  A  receiver  is  adapted  to  the  retort,  and  af- 
terwards two  bottles,  after  the  manner  of  Woulfe,  in  which  I 
diftribute  a  weight  of  diftiiled  water  equal  to  that  of  the  marine 
fait  made  ufe  of.  The  joinings  of  the  veffels  are  then  luted, 
but  with  the  greateft  caution  ;  and  when  the  apparatus  is  thus 
fitted  up,  a  quantity  of  fulphurick  acid  is  poured  through  the 
tubulure  equal  to  half  the  M'cight  of  the  fait.  A  confiderable 
ebullition  is  immediately  excited  :  and  when  this  effervefcence 
is  llackened,  the  retort  is  gradually  heated  and  the  mixture 
made  to  boil. 

The  acid  is  difcngagcd  in  the  flate  of  gas  ;  and  mixes  rap- 
idly with  the  water,  in  which  it  produces  a  confiderable  degree 
pf  he^t. 


f  5^  Oxigejtated  Murlatick  Acid, 

The  water  of  the  firft  bottle  is  ufually  faturated  with  th^ 
acid  gas,  and  forms  a  very  concentrated  pnd  fuming  acid  ;  and 
though  the  fecond  is  weaker,  it  may  be  carrried  to  any  defired 
tlegree  of  concentration,  by  impregnating  it  with  a  new  quan- 
tity of  the  gas. 

The  ancient  chemifls  were  divided  refpeding  the  nature  c 
the  muriatick  acid.     Becher  fuppofed  it  to  be'^rhe    fulphuric!: 
acid  modified  by  his  mercurial  earth. 

This  acid  is  fufceptible  of  combining  with  an  additional  dof 
ofoxigcne;  and,  what  is  very  extraordinary,  it  becomes  mor 
volatile  in  confequence  of  this  additional  quantity  ;  whereas  tlj . 
other  acids  appear  to  acquire  a  greater  degree  of  fixity  in  the 
fame  circumllances.  It  may  even  be  faid,  that  its  acid  virtues 
become  weaker  in  this  cafe,  fmce  its  affinities  with  alkalis  di- 
niinifh  ;  and  it  is  fo  far  from  reddening  blue  vegetable  colours, 
that  it  deftroys  them. 

Another  phenomenon  not  lefs  intercfting,  which  is  prefente4 
to  us  by  this  new  combination,  is,  that  though  the  muriatick 
acid  feizes  the  oxigene  with  avidity,  yet  it  contracts  fo  weak  i^ 
union  v.'ith  it,  that  it  yields  it  to  almoft  all  bodies,  and  the 
mere  adlion  of  light  alone  is  fufPicient  to  difengage  it. 

It  is  to  Scheele  that  we  are  indebted  for  the  difcovery  of  tht; 
cxigenated  muriatick  acid.  He  formed  it  in  the  year  1774,  by 
employing  the  muriatick  acid  as  a  folvent  for  manganefe.  He 
perceived  that  a  gas  was  difengaged,  which  poflefled  the  diftinc- 
tive  fmell  of  aqua  regia  ;  and  lie  was  of  opinion  that  in  this 
cafe  the  muriatick  acid  abandoned  its  phlogifton  to  the  maur 
ganefe  ;  in  confequence  of  which  notion  he  called  it  the  De- 
phlogifticated  Marine  Acid,  fjc  took  notice  of  the  principal 
and  truly  aftonifbing  properties  of  this  new  fubftance  ;  and  al| 
chemifts  lince  his  time  have  thought  their  attention  well  em- 
ployed in  examining  a  fubftance  which  exhibits  fuch  fnigul^ 
properties. 

To  attracl  this  acid,  I  place  a  large  glafs  alembick  of  one  fin- 
gle  piece  upon  a  fand  bath.  To  the  alembick  I  adapt  a  fmal: 
receiver  •,  and  to  the  receiver  three  or  four  fmall  bottles  nearly 
filled  with  diftilled  water,  and  ananged  according  to  the  method 
of  V/ctilfe.  I  difpofe  the  receiver  and  the  bottles  in  a  ciitern, 
the  places  of  junction  being  luted  with  fat  lute,  and  fe- 
cured  with  rags  foaked  in  the  lute  of  lime  and  white  of 
cjxg-  Laftly,  I  furround  the  bottles  with  pounded  ice. 
Wlien  the  apparatus  is  thus  difpofed,  I  introduce  into  the 
alembick  half  a  pound  of  manganefe  of  Cavennes,  and  pour 
upon  it,  at  feveral  repetitions,  three  pounds  of  fuming  muri- 
atick acid.     The  quantity  of  acid  which  I  pour  at  once  is  three- 


Oxvgenaied  Murlaiich  Add,  l^p 

liiices  ;  and  at   each  time  of  pouring  a  confiderable  efTervef- 

nce  is  excited.     I  do  not  pour  a  new   quantity  until  nothing 

lore  comes  over  into  the  receivers.     This  method  of  proceed- 

1^  is  indifpenfably  necefiary,  when  the  operator  is  defirous  of 

uiking  his  procefs  with  a  definite  quantity  of  the    materials. 

or  if  too  large  a  quantity  of  acid  be  poured  at  once,   it   is  im- 

■  offible  to  rellrain  the  vapours  ;  and  the  efFervefcence  will  throw 

a  portion  of  tlie  manganefe  into  the  receiver.       The  vapours 

which  are  developed  by  the  affiifion  of  muriatick  acid   are  of  a 

^reenifli  yellow  colour  ;    and  they  communicate  this  colour  ta 

the  water  when  they  combine  with  it.      AVhen   this  vapour  is- 

concentrated  by  means  of  the  ice,  and  the   water  is  faturated 

with  it,  it  forms  a  fcum  at  the  lurface,   which  is  precipitated 

M trough  the  liquid,  and  refembles  a  congealed  oil.     It  is  necelTa- 

V  to  affift  the  action  of  the  muriatick  acid  by  means  of  a  mod- 

-  'ate  heat  applied  to  the  fand  bath.      The  fecure  luting  of  the 

'dels  is  alfo  an  effential  circumftance  J    for  the  vapour  whicli 

ight  efcape  is  fuiTocating,  and  would  not  permit  the  chemift 

to  infpe6l  liis  operation  clofely.     It  is  eafy  to  difcover  the  place 

Xvhere  it  efcapes  through  the  lutes,  by  running  a  feather  dipped 

in  volatile  alkali  over  them  ;    the  combination  of  thcfe  vapours 

inftantly  forms  a  v/hite  cloud,  which  renders  the  place  vifible 

where  the  vapour  efcapes.     An  excellent  Memoir  of  Berthollet, 

publiflied  in  the  Annales  Chemiques,  may  be  confuhed  upon  the 

oxigenated  muriatick  acid. 

The  fame  oxigenated  muriatick  acid  may  be  obtained  by  dif- 
tilling,  in  a  fimilar  apparatus,  ten  pounds  of  marine  fait,  three 
or  four  pounds  of  manganefe,  and  ten  pounds  of  fulphurick 
acid. 

Mr.  Reboul  has  obferved  that  the  concrete  (late  of  this  acid 
i:>  a  cryilaliization  of  the  acid,  v/hich  takes  place  at  three  de- 
grees of  temperature  below  the  freezing  point  of  Reaumur. 
The  forms  which  have  been  obferved  are  thofe  of  a  quadrangular 
prifm  truncated  very  obliquely,  and  terminated  by  a  lozenge. 
He  has  likewife  obferved  hollow  hcxahedral  pyramids  on  the 
furface  of  the  liquor. 

To  make  ufe  of  the  oxrgensted  acid  in  the  arts,  and  in  order 
to  concentrate  a  greater  quantity  in  a  given  vohimc  of  water, 
the  vapour  is  made  to  pafs  through  a  folution  of  alkali.  A  white 
precipitate  is  at  lirH:  formed  in  the  iiqucr  ;  but  a  thort  time  af- 
terwards the  depofition  diminiihes,  and  bubbles  are  difcngaged, 
which  are  nothing  but  the  carbonick  acid.  In  this  cafe  two 
f:dts  are  formed,  the  oxigenated  muriate  and  the  ordinary  muri- 
ate. The  mere  imprefiion  of  light  is  fufficient  to  decompofc 
''"C  former,    and   convert  it  into  coalmen  fait.      This  lixivium 


jd»  Ofiiigenated  Muriaiich  Acid. 

Contains,  Indeed,  the  oxigenated  acid  in  a  ftronger  proportior 
The  execrable  fmell  of  the  acid  is  much  weakened.  It  may  be 
employed  for  various  ufes,  with  the  fame  fiiccefs,  and  with  great 
facility  ;  but  the  effedl  is  very  far  from  correfponding  with  the 
<5uantity  of  oxigenated  acid  which  enters  into  this  combination, 
jbecaufe  the  virtue  of  a  great  part  is  destroyed  by  its  union  with 
the  alkaline  bafis. 

The  oxigenated  muriatick  acid  has  an  exceflively  firongfrnell. 
It  acts  diredlly  on  the  larynx,  which  it  ftimulates,  excites  cough- 
ing, and  produces  violent   head-achs. 

Its  tafte  is  (liarp  and  bitter.  It  fpeedily  deflroys  the  colour 
of  tindlure  of  turnfole.  But  it  appears  that  the  property  which 
moft  oxigenated  fubftances  pofTefs,  of  reddening  blue  colours, 
arifes  only  from  the  combination  of  oxigenc  Vv^ith  the  colouring 
principles  ;  and  that,  when  this  combination  is  very  ftrong  and 
■rapid,  the  colour  is  deflroyed. 

The  oxigenated  muriatick  acid  with  which  a  folution  of  cauf-- 
tick  alkali  is  faturated,  affords,  by  evaporation  in  veffels  feclut; 
cd  from  the  light,  common  muriate  and  oxigenated  muriate. 
This  lafl  detonates  Upon  charcoal ;  is  more  foluble  in  hot  than 
in  cold  water  5  cry(ial]izes,  fometimes  in  hexaliedral  laminx, 
tind  oftener  in  rhomboidal  plates.  Thefc  cryilals  have  an  ar- 
gentine brilliancy,  like  mica.  Its  tafte  is  faint  ;  and  its  cryflals, 
when  they  are  dliTolved  in  the  mouth,  produce  a  fenfation  oF 
coolnefs  refembling  that  of   nitre. 

Mr.  BerthoUet  has  afcertained,  by  delicate  experiments  that 
the  oxigenated  muriatick  acid  which  exifls  in  the  oxigenated 
muriate  of  pot-afli,  contains  more  oxigene  than  an  equal  weight 
of  oxigenated  nniriatick  acid  diffolved  in  water;  and  this  has 
led  him  to.confider  the  oxigenated  acid  combined  in  the  muriate 
as  being  fuperoxigenated.  He  confiders  the  common  muriatick 
gas  with  relation  to  the  oxigenated  muriatick  gas,  the  fame  as 
the  nitrous  gas  ov  fulphureous  gas  with  refpedl  to  the  nitrick 
and  fulphinick  acide.  He  pretends  that  the  produ(fl;on  of  the 
fimple  muriate  and  the  oxigenated  muriate  in  the  fame  opera- 
tion, may  be  compared  to  the  action  of  the  nitrick  acid,  which 
in  many  cafes  produces  nitrate  and  nitrous  gas.  Hence  he  has 
confidered  the  muriatick  acid  as  a  pure  radical,  which,  combin- 
ed with  a  greater  or  Icfs  quantity  of  oxigene,  forms  either  fim- 
ple  muriatick  acid  gas,  or  the  oxigenated  muriatick  acid  gas. 

The  oxigenated  muriates  of  foda  do  not  differ  from  thofe  of 
pot-afh,  but  in  being  more  deliquefcent  and  foluble  in  alcohol, 
like  all  the  faits  of  this  nature. 

The  oxi.;enated  muriate  of  pot-aOi  gives  out  Its  o*xigene  in 
the  light,  and   by  diltillation  as  foon  as  the  veffei  is,  heated  t9 


■  tjunpowder  nvith  Muriatkk  ^t,  i6i 

. .  dnf  fs.  One  hundred  grains  of  this  fait  afford  feventy-five 
cubick  inches  of  oxigenous  gas  reduced  to  the  temperature  of 
twelve  degrees  of  Reaumur.  This  air  is  purer  than  the  others, 
and  may  be  employed  for  deHcate  experiments  of  the  oxigenat- 
cd  muriate  of  pot-afh,  when  cryftalUzed,  does  not  trouble  the 
folutions  of  nitrate  of  lead,  of  filver,  or  of  mercury. 

Mr.  Berthollet  has  fabricated  gunpowder,  by  fubftituting  the 
oxigenated  muriate  inflead  of  faltpetre.  The  eiFe£ls  it  produced, 
were  quadruple.  The  experiment  in  the  large  way,  which  was 
made  at  EfTone,  is  but  too  well  known  by  the  death  of  Mr.  Le 
Tors  and  Mademoifelle  Chevraud.  This  powder  exploded  the 
moment  the  mixture  was  triturated. 

The  oxigenated  muriatick  acid  whitens  thread  and  cotton. 
iFor  this  purpofe  the  cotton  is  boiled  in  a  weak  alkaline  lixivi- 
um ;  after  which  the  fluff  is  wrung  out,  and  lleeped  in  the  oxi- 
genated acid.  Care  is  taken  to  move  the  cloth  occafionally  ia 
the  fluid,  and  to  wring  it  out.  It  is  tiien  wafhed  in  a  large 
quantity  of  water,  to  deprive  it  of  the  fmell  with  which  it  is 
impregnated. 

I  have  applied  this  known  property  to  the  whitening  of  paper 
and  old  prints :  by  this  means  they  obtained  a  whitenefs  which 
they  never  before  pofTefled.  Common  ink  difappears  by  the 
a£lion  of  this  acid  -,  but  printers*  ink  is  not  attacked  by  it. 

Linen  and  cotton  cloths,  and  paper,  may  be  bleached  by  the 
vapour  of  the  oxigenated  marine  acid.  I  have  made  fome  ex- 
periments in  the  large  way,  which  have  convinced  me  of  the 
pofTibility  of  applying  this  method  to  the  arts.  The  memoir  in 
which  I  have  given  an  account  of  my  experiments,  will  be  print- 
ed in  the  volume  of   the   Academy  of  Paris  for  the  year  1787. 

The  oxigenated  muriatick  acid  thickens  oil-s  ;  and  oxides  met- 
als to  fuch  a  degree,  that  this  procefs  may  be  advantageoufly 
ufed  to  form  verditer. 

The  oxigenated  muriatick  acid  difTolves  metals  without  ef- 
fervefcence  ;  becaufe  its  oxigene  is  fufficient  to  oxide  them 
without  the  ncceffity  of  the  decompofition  of  water,  and  confe- 
quentlyof  the  difengagement  of  gas. 

This  acid  precipitates  mercury  from  its  folutions^  and  con- 
verts it  into  the  ftate  of  corrofive  fublimate. 

It  converts  fulphur  into  fulphurick  acid,  and  inftantly  deprives 
the  very  black  fulphurick  acid  of  its  colour. 

When  mixed  with  nitrous  gas,  it  pafles  to  the  flate  of  muriat- 
ick acid,  and  converts  part  of  the  gas  into  nitrick  acid. 

When  expofed  to  light,    it   aflbrda  pxigenous  gas,    and    the 
muriatick  acid  is  regenerated. 
W 


k 


t6t  Muriate  of  FoUap, 

The  muriatick  acid  acls  very  efEcacioufly  upon  metallick  ox- 
ides merely  in  confequence  of  its  becoming  oxigenated  ;  and: 
m  this  cafe  it  forms  with  them  falts,  which  are  more  or  left; 
oxigenated. 


ARTICLE    L 

Muriate  of  Pot-afh. 

Tiiis  fait  is  ftill  diftinguiflied  by  the  name  of  Febrifuge  fait  of 
Sylvius. 

It  has  a  difagreeable  ftrong  bitter   tafte. 

It  cryflallizes  in  cubes,  or  in  tetrahedral  prifms. 

It  depcripitates  upon  coals  ;  and  when  urged  by  a  violent  heat 
k  fufes,  and-  is  volatilized  without  decompofition. 

It  requires  three  times  its  weight  of  water,  at  the  temperature 
of  fixty  degrees  of  Fahrenheit,  for  its  folution.  , 

It  is  fubje<3:  to  fcarcely  any  alteration  in  the  air. 

One  hundred   grains  of  this  fait  contain    29.68    acid,  63.47^1 
alkali,  and  6.85  water.     It  is  frequently  met  with,  but  in  fmall 
quantities,  in  the  water  of  the  fea,  in  plafter,  in  the  alhes   of  j 
of  tobacco,  &c.     The  exiftence  of  this  fait  in  the  aflies  of  to-  i 
bacco  might  with  juftice  have  furprized  me,  as  I  had  reafon  xxr  ; 
expedl  the  muriate  of  foda  which  is   employed  in  the  operation  '' 
called  watering.     Was  the  foda  metamorphofed  into  pot-afli  by 
the  vegetable  fermentation  .''  This   may    be   determined  by  di- 
ttdi.  experiments. 


ARTICLE    H. 

Muriate  of  Soda. 

The  received  names  of  Marine  Salt,  Common  Salt,  and  Cu- 
linary Salt,  denote  the  combination  of  muriatick  acid  with  foda* 

This  fait  has  a  penetrating  but  not  bitter  tafte.  It  depre- 
ciates on  coals,  fufes,  and  is  volatilized  by  the  heat  of  a  glafs- 
maker's  furnace,  without  decompofition. 

It  is  foluble  in  2.5  times  its  weight  of  water,  at  fixty  degrees 
of  Fahrenheit's  thermometer. 

One  hundred  grains  of  this  fait  contain  33.3  acid,  50  of  alka- 
li,  and  16.7  of  water. 

It  cryftallizes  in  cubes.  Mr.  Gmelin  has  informed  us  that 
the  fait  of  the  fait  lakes  in  the  environs  of  Seliian  on  the  banks 
©f  the  Cafpiaa  fea,  forms  cubical  and  rhombpidal  cryftals. 


1 


J\4uriate  of  Soda  or  Common  Sa/t.  ^6$ 

Mr.  De  Lifle  obferves,  that  a   folution  of  marine  fait,  left  to 

fenfible  evaporation   during  five  years  by  Mr.  Rouelle,  had 

rmed  regular  oftahedral  cryftals  refembling  thofe  of  alum. 

Marine  fait  may  be  obtained  in  oftahedrons,  by  pouring  frefii 
urine  into  a  very  pure  folution  of  frefh  fait.  Mr.  Berniard  is 
convinced  that  this  addition  changed  only  the  form  of  the  fait, 
without  altering  its  nature. 

Common  fait  is  found  native  in  many  places.  Catalonia,  Cal- 
abria, Switzerland,  Hungary,  and  Tyrol,  poflefs  mines  which  arp 
more  or  lefs  abundant.  The  richeft  fait  mines  are  thofe  of  Wie- 
liczka  in  Poland.  Mr.  Berniard  has  given  us  a  defcription  of 
■them  in  the  Journal  de  Phyfique  ;  and  Mr.  Macquart,  in  his 
EfPays  on  Mineralogy,  has  added  interefting  details  concerning 
the  working  of  thefe  mines. 

Our  fait  fprings  in  Lorraine  and  ^ranche-compte,  and  fome 
Indications  afforded  by  Bleton,  have  appeared  fufHcient  motives 
*o  Mr.  Thouvenel  to  prefume  that  fait  mines  exift  in  our  king- 
dom. This  chemift  exprelTes  himfelf  in  the  following  man- 
ner : 

"At  the  diflance  of  two  leagues  from  Saverne,  between  the 
village  of  Huctenhaufen  ai^id  that  of  Garbourg,  in  a  lofty  moun- 
tain called  Penfenperch,  there  are  two  great  refervoirs  of  fait 
water  ;  the  one  to  the  eaft,  at  the  heud  of  a  large  deep  and 
narrow  valley,  which  is  called  the  great  Limerthaal  ;  the  other 
to  the  weft,  upon  the  oppofite  flope,  towards  Garbourg.  They 
communicate  together  by  five  fmall  ftreams,  which  are  detach- 
ed from  the  upper  refervoir,  and  unite  in  tlie  lower  one.  From 
thefe  two  fait  refervoirs  flow  two  large  ftreams  -,  the  upper 
runs  into  Franche-compte,  and  the  lower  into  Lorraine,  where 
■hey  fupply  the  well  known  fait  works." 

The  waters  therefore  flow  to  the  diftance  of  feventy  leagues 
from  the  refervoir. 

Salt  mines  appear  to  owe  their  origin  to  the  drying  up  of 
vaft  lakes.  The  fliells  and  madrepores  found  in  the  immenfe 
mines  of  Poland  are  proofs  of  marine  depofitions.  There  are 
I  ike  wife  fome  feas  in  which  tjie  fait  is  fo  abundant,  that  it  is 
lepofited  at  the  bottom  of  the  water  ;  as  appears  from  the 
analyfis  of  the  water  of  the  lake  Afphaltites,  made  by  MefTrs. 
Maquer  and  Sage. 

This  native  fait  is  often  coloured  ;  and  as  in  this  ftate  it 
pofTelTes  confiderable  brilliancy,  it  is  called  Sal-gem.  It  al- 
moft  always  contains  an  oxide  of  iron,  which  colours  it. 

As  thefe  fait  mines  are  neither  fufficiently  abundant  to  fup- 
ply the  wants  of  the  inhabitants  of  the  globe,  nor  diftributed 
>vith  that  uniformity  as  to  permit  all  nations  to  have  ready  re^- 


t64  Ext^aBion  of  Salt  from  Water: 

courfe  to  them,  it  has  been  found  neceflary  to  extract  the  fait 
from  the  water  of  the  fea.  The  fea  does  not  contain  an  equal 
quantity  in  all  climates  :  Ingenhoufz  has  fliewn  us  that  the 
northern  feas  contain  lefs  than  the  fouthern.  Marine  fait  is  lb 
abundant  in  Egypt,  that,  according  to  Haflelquift,  a  frefli-water 
fpring  is  a  treafure  which  is  fecretly  tranfmitted  from  father  to 
fon. 

The  method  of  extrafling  the  water  of  the  fea  varies  accor- 
ding to  the  climates. 

I.  In  the  northern  provinces,  the  fait  fands  of  the  fea  coaft 
;jire  wafhed  with  the  leaft  poflible  quantity  of  water,  and  the 
fait  is  obtained  by  evaporation.—^See  the  defcription  of  this  pro- 
cefs  by  Mr.  Guettard. 

?.  In  very  cold  countries,  fait  water  is  concentrated  by  freez-s 
jng,  and  the  refidue  is  evaporated  by  fire. — See  Wallerius. 

3.  At  the  fait  fprings  of  Lorraine  and  Franche-compte,  the 
water  is  pumped  up,  and  fufFered  to  fall  upon  heaps  of  thorns 
"which  divide  it,  and  caufe  a  part  to  evaporate.  The  farther 
concentration  is  efFe£led  in  boilers. 

4.  In  the  fouthern  provinces,  at  Peccais,  at  Peyrat,  at  Cette 
and  elfewhere,  the  extraction  is  begun  by  feparating  a  certain 
quantity  of  water  from  the  general  mafs  of  the  fea,  which  is  fuf- 
fered  to  remain  in  fquare  fpaces,  called  Partenemens.  For 
this  purpofe  it  is  neceiTary  to  have  fluices  vv'hich  may  be  open- 
ed and  {hut  at  pleafure,  and  to  form  furrounding  walls  which 
^prevent  all  communication  with  the  fea,  except  by  means  of 
thefe  gates.  It  is  in  the  partenemens  that  the  water  goes 
through  the  firft  ftate  of  evaporation  ;  and  when  it  begins  to 
depofite  its  fait,  it  is  raifed  by  bucket  wheels  to  other  fquare 
compartments,  called  Tables,    were  the  evaporation  finiOies. 

The  fait  is  heaped  together,  to  form  the  cammelles ;  in 
"which  ftate  it  is  left  for  three  years,  in  order  that  the  dcH- 
quefcent  falts  may  flow  out  of  it  •,  and,  after  this  interval  of 
time,  it  is  carried  to  market. 

Exertions  and  enquiries  have  long  fince  been  made  to  difcov- 
cr  a  cheap  method  of  decompofing  marine  fait,  to  obtain  the 
mineral  alkali  at  a  low  price,  which  is  of  fuch  extenfive  ufe  in 
the  manufactories  of  foap,  glafs,  bleaching,  &c.  The  proceflcs 
hitherto  difcovered  are  the  following : 

1.  The  nitrick  acid  difengages  the  muriatick  acid,  and  forms 
nitate  of  foda,  yvhich  may  be  eafily  decompofed  by   detonation. 

2.  Pot-alli  difplaces  the  foda,  even  in  the  cold,  as  I  found  by 
experiment. 

3.  The  fulphurick  acid  forms  fulphate  of  foda  by  decomp,p- 
(in^  the  marine  fait  \  the  new  fait,  when  heated  with  charcoalj, 


Muriate  of  Ammc72lack.  1 65 

is  deftroyed  ;  but  the  fulphure  of  foda,  or  liver  of  fulphur,  is 
formed,  which  is  difficult  to  be  entirely  feparated  ;  and  this 
procefs  does  not  appear  to  me  to  be  economical.  The  fulphure 
may  likewife  be  decompofed  by  the  acetite  of  barytes,  and  the 
foda  afterwards  obtained  by  calcination  of  the  acetite  of  foda. 

4.  MargrafF  tried  in  vain  to  acomplifh  this  purpofe,  by  means 
of  lime,  ferpentine,  iron,  clay,  &c.  He  adds  that  if  common 
fait  be  thrown  upon  lead  heated  to  rednefs,  the  fait  is  decom- 
pofed, and  muriate  of  lead  is  formed. 

5.  Scheele  has  has  pointed  out  the  oxides  of  lead  for  the 
decompofition  of  common  fait.  If  common  fait  be  mixed  with 
litharge,  and  made  into  a  pafte,  the  litharge  gradually  lofes  its 
colour,  and  becomes  converted  into  a  white  matter  from  which 
the  foda  may  be  extracted  by  wafhing.  It  is  by  procefles  of 
this  kind  that  Turner  extracts  it  in  England  ;  but  this  decom- 
pofition never  appeared  to  me  to  be  complete  unlefs  the  litharge 
was  employed  in  a  proportion  quadruple  to  that  of  the  fait.  I 
have  obferved  that  almoft  all  bodies  are  capable  of  alkalizing 
marine  fait,  but  that  the  abfolute  decompofition  is  very  difficult 

6.  Barytes  decompofes  it  likewife,  according  to  the  experi- 
ments of  Bergmann. 

7.  The  vegetable  acids,  combined  with  lead,  may  likewife  be 
ufed  to  decompofe  common  fait.  When  thefe  falts  are  mixed, 
a  decompofition  takes  place  :  the  muriate  of  lead  falls  down  ; 
gnd  the  vegetable  acid,  united  to  the  foda,  remains  in  folution. 
The  vegetable  acid  may  be  diffipated  by  evaporation  and  calcin- 
ation :  and  the  alkali  remains  difengaged. 

Marine  fait  is  more  efpecially  employed  at  our  tables,  and  in 
culinary  purpofes.  It  removes  and  correds  the  infipidity  of  our 
food,  and  at  the  fame  time  facilitates  digeltion.  It  is  ufed  in  a 
large  proportion  to  preferve  flefli  from  putrefadion  ;  but  in  a 
fmall  dofe  it  haftens  that  procels,  according  to  the  experiments 
pf  Pringle,  Macbride,  Gardane,  &c. 


ARTICLE      III. 

Muriate  of  Ammoniack. 

Of  all  the  combinations  of  ammoniack  this  is  the  mod  inter- 
erting,  and  the  moll  generally  ufed.  It  is  known  by  the  name 
of  Sal  Ammoniack. 

This  fait  may  be  diredJy  formed  by  decompofing  the  muriate 
of  lime  by  the  means  of  ammoniack,  as  Mr.  Baume  has  prac- 
pfed  at  Paris.  But  almoft  all  the  fal  ammoniack  which  circu- 
4a^es  in  cojiunerce  is  brought  to  us  from  Egypt,  where  it  is  ex- 


I 


*66  J^fitroBion  of  tal  Amtnoniach, 

tra£led  by  diftillation  from-foot,  by  the  combuftion  of  the  cx« 
crements  of  fuch  animals  as  feed  on  faline  j^nJants. 

The  details  of  the  procefs  which  is  ufed  have  not  been  very 
long  known.  One  of  the  firft  writers  who  gave  a  defcription  of 
this  operation  is  father  Sicard.  He  informed  us,  in  1716,  that 
diftilling  veiTels  were  charged  with  the  foot  of  the  excrements  of 
oxen,  to  which  fea  fait  and  camels'  urine  were  added. 

Mr.  Lemaire,  conful  at  Cairo,  in  a  letter  written  to  the  acad- 
emy of  Sciences  in  1720,  affirms  that  neither  urine  nor  fea  fait 
arc  added. 

Mr.  Haflelquift  has  communicated  to  the  Academy  of  Stock- 
holm a  confiderably  extenfive  defcription  of  the  procefs  :  by 
which  we  learn  that  the  dung  of  all  animals  which  feed  on  fa- 
line  plants  is  indifcriminately  ufed,  and  that  the  foot  is  diftilled, 
to  obtain  fal  ammoniack. 

This  dung  is  dried  by  applying  it  againft  the  walls  :  and  it  is 
burned  inftead  of  wood,  in  fuch  countries  as  do  not  poiTefs  that 
fuel.  The  fublimation  is  performed  in  large  round  bottles  of 
one  foot  and  a  half  diameter,  terminating  in  a  neck  of  two 
inches  in  height  ;  and  they  are  filled  to  within  four  inches  of 
the  neck.  The  fire  is  kept  up  during  three  times  twenty-four 
hours  ;  the  fait  is  fublimed  to  the  upper  part  of  thefe  vefTels, 
-where  it  forms  a  mafs  of  the  fame  figure  as  the  veflels  them- 
felves.  Twenty  pounds  of  foot  afford  fix  pounds  of  fal  ammon- 
iack, according  to  Rudenfkield. 

I  was  always  of  opinion  that  fal  ammoniack  might  be  extra£l- 
ed  by  treating  the  dung  of  the  numerous  animals  which  feed  on 
faline  plants  m  the  plains  of  La  Camargue  and  La  Crau,  in  the 
fame  manner  ;  and  after  having  procured,  with  the  greatefi  dif- 
ficulty, two  pounds  of  the  foot,  I  extracled  from  it  four  ounce* 
of  fal  ammoniack.  I  muft  obferve,  to  fave  much  trouble  to 
thofe  who  may  wifli  to  follow  this  branch  of  commerce,  that 
the  dung  produced  during  the  fummer,  the  fpring,  or  the  au- 
tunm,does  not  afford  this  fait.  I  did  not  know  to  what  circum- 
ttance  to  attribute  the  verfatility  of  my  refults,  until  I  found 
that  thefe  animals  do  not  eat  faline  vegetables,  excepting  at  th^ 
time  when  frefh  plants  cannot  be  had  ;  and  that  they  are  reduc- 
ed to  the  neceffity  of  h?;vlng  recourfe  to  faline  plants  only  dur- 
ing the  three  winter  months.  This  obfervation  appears  to  me 
to  be  a  proof,  that  marine  fait  is  decompofed  in  the  firfl  pafia- 
ges  ;  and  that  the  foda  is  modified  to  the  fiate  of  ammoniack. 

Sal  ammoniack  is  continually  fublimed  through  the  aperture^ 
of  volcanick  mountains.     Mr.  Ferber  found  it  ;    and  Mr.  Sage 
admitted  its  exiftence  among  volcanick  producls.      It   is  found 
in  the  grottos  of  Puzzolo,   according  to   MefTrs.  Swab,  Schet 
fer,  &c. 


NttrO'Muriatich  Acid*  l6^ 

it  IS  found  in  the  country  of  the  Calmuks.  Model  ana- 
lyfed  it. 

It  is  alfo  produced  in  the  human  body,  and  exhales  by  perfpi- 
tation  in  malignant  fevers.  Mr.  Model  has  proved  this  fadl  in 
liis  own  perfon  :  for  at  the  time  of  a  violent  Aveat  which  termi- 
nated a  malignant  fever,  he  waflied  his  hands  in  a  folution  of 
pot-afli,  and  obferved  that  a  prodigious  quantity  of  alkaline 
gas  was  difengaged. 

Sal  ammoniack  cryftallizes  by  evaporation  in  quadrangular 
pyramids.  It  is  often  obtained  in  rhombick  cryftals  by  fublima- 
tion.  The  concave  face  of  the  loaves  of  fal  ammoniack  in 
commerce  is  fometimes  covered  with  thefe  cryftals. 

This  fait  has  a  penetrating,  acrid,  urinous  tafte.  It  pofTeiTes  a 
degree  of  dudlility  which  renders  it  flexible,  and  caufes  it  to 
yield  to  a  blow  of  the  hammer.  It  does  not  change  in  the  air  ; 
which  circumftance  renders  it  probable  that  our  fal  ammoniack 
is  different  from  that  mentioned  by  Pliny  and  Agricola,  as  that 
attracted  humidity.  Three  parts  and  a  half  of  water  diflblve  , 
one  part  of  fal  ammoniack,  at  fixty  degrees  of  Fahrenheit's  ther- 
mometer :  a  confiderable  degree  of  cold  is  produced  by  its  fo- 
lution. 

One  hundred  parts  of  fal  ammoniack  contain  fifty-two  parts 
acid,  forty  ammoniack,  and  eight  water. 

This  fait  is  not  at  all  decompofed  by  clay ;  nor  by  magnefia 
except  with  difficulty,  and  in  part  only  ;  but  it  is  completely  de- 
compofed by  lime  and  fixed  alkalis.  The  fulphurick  and  ni- 
trick  acids  difengage  its  acid. 

This  fait  is  ufed  in  dying,  to  bring  out  certain  colours.  It  is 
mixed  with  aqua  fortis,  to  increafe  its  folvent  power. 

It  is  ufed  in  foldering;  in  which  operation  it  pofiefies  the 
double  advantage  of  clearing  the  metallick  furface,  and  prevent- 
ing its  oxidation. 


CHAPTER    V. 

Concerning  the  Nitro-muriatlck  Acid. 

THE  acid  which  we  call  Nitro-muriatick,  is  a  combinatioa 
of  the  nitrlck  and  muriatick  acids. 

Our  predecefTors  diftinguifhed  it  by  the  name  of  Aqua  Regia, 
on  account  of  its  property  of  diifolving  gold. 

There  are  feyeral  known  procefles  for  making  this  mixed 
Jicid. 


!§68  NitrO'Munatich  Add. 

If  two  ounces  of  common  fait  be  diflilled  with  four  of  nitrick 
acid,  the  acid  which  comes  over  into  the  receiver  will  be  good 
nitro-muriatick  acid. 

This  is  the  procefs  of  Mr.  Baume. 

The  nitrate  of  pot-a(h  may  be  decompofed  by  diflilling  two 
parts  of  muriatick  acid  from  one  of  this  fait :  good  aqua  regia 
is  the  produ6l  of  this  operation  ;  and  the  refidue  is  a  muriate 
of  pot-afh,  according  to  Mr.  Cornette. 

Boerhaave  affirms  that  he  obtained  a  good  aqua  regia,  by  dif- 
tilling  a  mixture  of  two  parts  of  nitre,  three  of  fulphate  of  iron 
or  martial  vitriol,  and  five  of  common  fait. 

The  fimple  diftillation  of  nitre  of  the  firfl  boiling  affords 
aqua  regia  ;  which  is  employed  by.  the  diers  in  the  folution  of^ 
tin,  for  the  compofition  of  the  fcarlet  die.  This  aqua  fortis  is 
a  true  aqua  regia  :  and  it  is  by  virtue  of  the  mixture  of  acids 
that  it  diflblves  tin  ;  for  if  it  confided  of  the  nitrick  acid  in  a 
ftate  of  too  great  purity,  it  would  corrode  and  oxide  t\iQ  metal 
without  difiblving  it.  The  diers  then  fay  that  the  aqua  fortis 
precipitates  the  tin  ;  and  they  correal  the  acid  by  diflbving  fal 
ammoniack  or  common  fait  in  it. 

Four  ounces  of  fal  ammoniack  in  powder,  diiTolved  gradually, 
and  in  the  cold,  in  one  pound  of  nitrick,  form  an  excellent  aqua 
regia.  An  oxigenated  muriatick  acid  gas  is  difengaged  for  a 
long  time  ;  which  it  is  imprudent  to  attempt  to  coerce,  and 
which  ought  to  be  fufFered  to  efcape  by  convenient  apertures. 

Aqua  regia  is  like  wife  formed  by  mixing  together  two  parts 
of  pure  nitrick  acid  and  one  of  muriatick  acid. 

The  very  evident  fmell  of  oxigenated  muriatick  acid,  which 
is  difengaged  in  every  procefs  which  can  be  adopted  to  form  the 
acid  at  prefent  in  queftion  •,  and  the  property  which  it  polfefles 
equally  with  the  oxigenated  muriatick  acid,  of  difiblving  gold, 
have  led  certain  chemifhs  to  infer  that,  in  the  mixture  of  thefe 
tv/o  acids,  the  muriatick  acid  feized  the  oxlgene  of  the  nitrick, 
and  afiumed  the  character  of  oxigenated  muriatick  acid;  fo 
that  the  nitrick  acid  was  confidered  as  anfwering  no  other  pur- 
pofe  than  that  of  oxigenating  the  muriatick.  But  this  fyftem  is 
inconfiftent ;  and  though  the  virtues  of  the  muriatick  acid  are 
modified  by  this  mixture,  and  it  is  oxided  by  the  decompofition 
of  a  portion  of  the  nitrick  acid,  neverthelefs  the  two  acids  (till 
cxifl  in  the  aqua  regia  :  and  I  am  convinced  that  the  beft  made 
aqua  regia,  faturated  with  pot-afii,  will  aflbrd  the  ordinary  muri- 
ate, the  oxigenated  muriate,  and  the  nitrate.  It  appears  to  me 
that  the  powerful  action  of  aqua  regia,  depends  fimply  on  the 
union  of  the  two  acids  •,  one  of  which  is  exceedingly  well  cal- 
culated to  oxide  the  met.ils,  and  the  other  difiblves  the  oxides 
©r  calces  with  the  greatcfl  avidity. 


jticld  of  BortiK*  169 

CHAPIER     Vr. 

♦  Concerning  the  Acid  of  Borax . 

r  THE  ackl  of  borax,  more  generally  known  by  the  name  of 
•bf  Homberg's  Sedative  Salt,  is  almoft  always  afforded  by  the 
Hecompofition  of  the  borate  of  foda,  or  borax.  But  it  lias  been 
>^ound  perfetlly  formed  in  certain  places  and  we  have  reafon  to 
hope  that  we  ftiall  fpeedily  acquire  more  accurate  information 
itefpefting  its  nature. 

Mr.  Hoefer,  dire£lor  of  the  Parmacies  of  TufCany,  was  the 
firft  who  deteded  this  acid  fait  in  the  waters  of  the  lake  Cher- 
-chiajo,  near  Monte-rotondo,  in  the  inferiour  province  of  Sienna  ; 
thefe  waters  are  very  hot,  and  they  afforded  him  three  ounces  of 
the  pure  acid  in  one  hundred  and  twenty  pounds  of  the  water. 
This  fame  chemilt  having  evaporated  twelve  thoufand  two  hun  - 
^dred  and  eighty  grains  of  the  water  of  the  lake  of  Caflelnuovo, 
vobtained  one  hundred  and  twenty  grains.  He  prefumes> 
moreover,  that  it  might  be  found  in  the  water  of  feveral  other 
lakes  fuch  as  thofe  of  Laffo,  Monte-cerbeloni,  &c. 
'  Mr.  Sage  has  dcpofited  in  the  hands  of  the  Royal  Academy  of 
Sciences  Ibme  acid  of  borax^  brought  from  the  mines  of 
Tufcany  by  Mr.  Beffon,  who  colleded  it  himfelf. 

Mr.  Weflrumb  found  fedative  fait  in  the  ftone  called  Cubick 
Quartz  of  Luneburg.  He  obtained  it  by  decompofing  this 
ftone  by  the  acids  of  fulphur,  nitre,  &c.  The  refult  of  his  anal- 
yfis  is  the  following  : 

Sedative  fait  —  ^% 

Calcareous  earth  — ^        ^^q. 

Magnefia  —  -j-fj. 

Clay  and  filex         —  ^^-^ 

Iron  —  ^4^  to  ^i.^ 

This  ftone  according  to  the  obfervations  of  Laffius,  has  the 
form  of  fmall  cubical  cryflals,  fometimes  tranfparent,  in  other 
fpecimens  milky,  and  affords  fparks  with  the  fleel. 

The  acid  of  borax  is  generally  found  combined  with  foda. 
It  is  from  this  combination  that  it  is  difengaged,  and  obtain- 
ed either  by  fublimation  or  cryllallization.      ^^' 

When   it  is   propofed    to    obtain  it    by    fublimation    three 

pounds  of  calcined  fulphate  of  iron,  and  two  ounces  of  borate 

of  foda  are  diflblvcd  in  three  pounds  of  water.     The  foiution  is 

then  I'ltered,  and  evaporaied  to  a  pciliclc  5  after  which  the  fub-. 

X 


..[f^o  Acid  of  Borax, 

limation  is  performed  in  a  cucurbit  of  glafs  with  its  head. .  Tiie^ 
acid  of  borax  attaches  itfelf  to  the  internal  furface  of  the  head 
from  which  it  may  be  fwept  by  a  feather. 

Homberg  obtained  it  by  decompofing  of  borax  with  the  ful- 
phurick  acid.  This  procefs  fucceeded  with  me  wonderfully  well. 
For  this  purpofe  I  make  ufe  of  a  glafs  cucurbit  with  its  head, 
which  I  place  on  a  fand  bath.  I  then  pour  upon  the  borax  half 
its  weight  of  fulphurick  acid,  and  proceed  to  fublimation. 
The  fublimated  acid  is  of  the  mod  beautiful  whitenefs. 

Stahl,  and  Lemery  the  younger,  obtained  the  fame  acid  by 
making  ufe  of  the  nitrick  and  muriatick  acids. 

To  extra£l  the  acid  of  borax  by  cryftallization,  the  borax  is 
diflblved  in  hot  water,  and  an  excefs  of  fulphurick  acid  is  pour- 
ed in.  A  fait  is  depofited  during  the  cooling  on  the  fide  of 
^the  veffel,  in  the  form  of  thin  round  plates,  applied  one  up- 
on the  other.  This  fait  when  dry  is  very  light,  very  white  anid  of 
•a  fdvery  appearance,     ft  is  the  acid  of  borax. 

:We  are  indebted  to  Geoffrey  for  this  procefs.  Baron  has 
tadded  two  fa£^s  :  the  firft,  that  the  vegetable  acids  are  equally 
capable  of  decompofing  borax  ;  and  the  fecond,  that  borax  may 
-be  regenerated  by  combining   the  acid   of  borax  with  foda. 

This  acid  irray  be  purified  by  folution,  filtration,  and  evapo« 
ration  -,  but  it  miift  be  obferved,  that  a  confidcrable  part  is  vol- 
atilized with  the  water  which  flies  off  in  the  evaporation. 

The  acid  of  borax  has  a  faline  cool  tafte.  It  colours  the  tinc- 
ture of  turnfoie,  fyrup  of  violets,  &c.  red. 

One  pound  of  boiling  water  diffolved  no  more  than  one 
hundred  and  eighty-three  grains  according  to  Mr.  De  Morveau. 

Alcohol  difTolves  it  more  eafily  ;  and  the  flame  which  this 
folution  aflords  is  of  a  beautiful  green.  This  acid,  when  ex- 
pofed  to  the  fire,  is  reduced  to  avitriform  and  tranfparent  fub- 
iitance,.inftead  of  rifing  ;  which  proves,  as  Rouelle  has  obferv- 
ed,  that  it  is  only  fublimed  by  favour  of  the  water,  with  which 
it  forms  a  very  volatile  compound. 

As  moft  of  the  known  acids  decompofe  this  acid,  and  exhibit 
it  in  the  fame  form,  it  has  been  thought  a  juftifiable  conclufion 
that  it  exifts  ready  formed  in  the  borax.  Mr.  Baume  has  even 
•affirmed  that  he  comp&fed  this  acid  by  leaving  a  miicture  of  grey 
day,  greafe,  and  cows  dung  expofed  to  the  air  in  a  cellar.  But 
Mr.  Wiegleb,  after  an  unfuccefsful  labour  of  three  years  and  a 
half,  thinks  himfelf  authorized  to  give  a  formal  negative  to  the 
-French  chemifl. 

Mr.  Cadet  has  endeavoured  to  prove 1.  That  the  acid  of 

borax   always   retains  a   portion  of  the  acid    employed  in  the 
operation.     2.  That  this  fame  acid  has  ftUl  the   mineral  al^ 


Borate  of  PoUaJk  and  Sod^,  I  ^  I 

all  for  its  bafis. — Mr.  De  Morveau  has,  with  his  ufual  fagacity, 
difcufled  all  the  proofs  brought  forward  by  Mr.  Cadet  •,  he  Ivas 
(hewn  that  none  of  them  are  conclufive,  atid  that  the  acid  of 
borax  is  entitled  to  retain  its  place  amoijg  the  phemical  ek- 
ments. 


ARTICLE    I. 

Borate  of  Pot-afh. 

f 

The  acid  of  borax  combined  with  pot-afli  forms  this  fait.  It 
may  be  obtained  either  by  the  dire£l  combination  of  thefe  two 
feparate  principles,  or  by  decompofmg  borax  by  the  addition  of 
pot-a{h. 

This  fait,  which  is  yet  little  known,  aflPorded  Mr.  EaumS 
fmall  cryftals. 

The  acids  difengage  it  by  fei?ing  its  alkaline  bafe. 


ARTICLE  II. 

JBorate  of  Soda. 

This  combination  forms  Bprax,  properly  fo  called. 

It  is  brought  to  us  from  the  Indies  *,  and  its  origin  is  ftill  un- 
known.* 

The  article  borax  may  be  confulted  in  Bomare's  Didlionary 
of  Natural  Hiitory 

It  does  not  appear  that  borax  was  known  to  the  ancients. 
The  chryfocolla,  of  which  Diofcorides  fpeaks,  was  nothing  but 
an  artificial  folder,  compofed  by  the  goldfmiths  themfelves, 
with  the  urine  of  children  and  ruft  of  copper,  which  were 
beaten  together  in  a  mortar  of  the  fame  metal. 

The  word  Borax  is  found  for  the  firft  time  in  the  works  of 
Geber.  Every  thing  which  has  beei^  written  fincc  that  time 
concerning  borax,  is  applicable  to  the  fubftance  which  is  at 
prefent  known  to  us  by  that  name. 

Borax  is  found  i«  commerce  in  three  different  ftates. 


•  The  origin  of  Borax  is  very  well  afcertained  in  two  Papers,  in  the 
fcvcnty-feTenth  volume  of  the  Philofophlcal  Tranfa<5tions  Number  xxviii 
and  xxix.  It  is  dug  up  in  a  cryftallized  ftate  from  the  hottona  of  certain  Talt. 
lakes  in  a  mountainous,  barren,  volcanick  diftridV,  about  twenty-five  d^ys 
journey  to  the  eaftward  of  Laffa,  the  capital  of  the  kingdom  of  Thibet.   T. 


17*  Hijhry  and  Purification  of  Bora>i, 

The  firft  is  brute  borax,  tincall,  or  chryfocolla.  It  comes  li 
us  from  Perfia,  and  is  enveloped  and  foiled  by  a  greafy  covering 
The  pieces  of  brute  borax  have  alnioft  ail  of  them  the  form  of  ^ 
fix-fided  prifm,  flightly  flattened,  and  terminated  by  a  dihedral 
pyramid.  The  fracture  of  thefe  cryftals  is  brilliant,  \rith  a. 
greenifh  caft.  This  kind  of  borax  is  very  impure.  It  is  pre- 
tended that  borax  is  extracted  from  the  Lake  of  Necbal,  in  the 
kingdom  of  Grand  Thibet.  This  lake  is  filled  with  water  dur- 
ing the  winter,  which  exhales  in  the  fummer  •,  and  when  the 
"waters  are  low^  workmen  enter,  who  detach  the  cryftals  from 
the  muddy  bottom,  and  put  them  into  bafkets. 

The  Weft-Indies  contain  borax.  It  is  to  Mr.  Antony  Garcra, 
a  phyfician  eflabHlhed  at  Potofi,  that  we  are  indebted  for  this 
difcovery.  The  mines  of  Riquintipa,  and  thofe  in  the  neigh- 
bourhood of  Efcapa,  afford  this  fait  in  abundance.  The  natives; 
ufe  it  in  the  fufion  of  copper  ores. 

The  fecond  kind  of  borax  known  in  commerce  comes  fron> 
China.  It  is  purer  than  the  preceding,  and  has  the  form  of 
fmall  plates  cryftallized  upon  one  of  their  furfaces,  on  which 
the  rudiments  of  prifms  may  be  perceived.  This  borax  is  mix- 
ed with  a  white  powder,  whieli  appears  to  be  of  an  argillaceoui 
nature. 

Thefe  feveral  kinds  of  borax  have  been  purified  at  Venice 
for  a  long  time,  and  afterwards  in  Holland  5  but  Meflirs.  La- 
guiller  refine  it  at  prefent  in  Paris  ;  and  this  purified  borax  forms 
the  third  kind  which  is  met  with  in  commerce. 

In  order  to  purify  borax,  nothing  more  is  neceflary  than  to 
clear  it  of  the  un£luous  fubftance  which  foils  it  and  irnpedes  its 
folution. 

Crude  borax  added  to  a  folution  of  mineral  alkali,  is  more 
completely  dilfolved,  and  may  be  obtained  of  confiderable  beau- 
ty by  a  firft  cryftallization  ;  but  it  retains  the  alkali  made  ufe 
of  ;  aiid  borax,  purified  in  this  manner,  poiTefies  a  greater  por- 
tion of  alkali  than  in  its  crude  ftate. 

The  oily  part  of  borax  may  be  deflroyed  by  calcination.  By 
this  treatment  it  becomes  more  foluble,  and  may  in  fact  be  puri- 
fied in  this  way.  But  the  method  is  attended  with  a  confidera- 
ble lofs,  and  is  not  fo  advantageous  as  might  be  imagined. 

The  moft  fimple  method  of  purifying  borax,  confifts  in  boiling 
it  ftron;Tly,  and  for  a  long  time.  Tliis  folution  being  filtrated, 
affords  by  evaporation  cryftals  rather  foul,  which  may  be  puri- 
fied by  a  fecond  operation  fimilar  to  the  foregoing.  I  have  triet^ 
all  thefe  procefles  in  the  large  way  j  and  the  latter  appe^re^i  t 
jTie  to  be  the  moft  fim nle. 


Properties  and  Habitudej  of  Borax.  i^a 

•Purified  borax  is  white, tranfparent,  and  has  a  fomewhat  greafy 
appearance  in  its  fradture. 

It  cryftallizes  in  hexahedral  prifms,  terminated  by  trihedral 
:^.nd  fometimes  hexahedral  pyramids. 

It  has  a  ftyptick  tafte. 

It  converts  fyrup  of  violets  to  a  green. 

When  borax  is  expofed  to  the  fire,  it  fwells  up,  the  water  of 
ryftallization  is  diffipated  in  the  form  of  vapour  ;  and  the  fait 
then  becomes  converted  into  a  porous,  light,  white,  and  opake 
mafs,  commonly  called  Calcined  Borax.  If  the  fire  be  more 
fr.rongly  urged,  it  aflumcs  a  pafty  appearance,  and  is  at  length 
lufed  into  a  tranfparent  glafs  of  a  greenifh  yellow  colour,  folu- 
hie  in  water  *,  and  which  lofes  its  tranfparency  by  expofure  to 
the  air,  in  confequence  of  a  white  efflorefcence  that  forms  upon 
its  furface. 

This  fait  requires  eighteen  times  its  weight  of  water,  at  the 
jemperature  of  fixty  degrees  of  Fahrenheit's  thermometer,  to 
aiflblve  it.     Boiling  water  dilTolves  one  fixth  of  its  weight. 

Barytes  and  magnefia  decompofe  borax.  Lime-water  precip- 
itates the  folution  of  this  fait  *,  and  if  quick-lime  be  boiled  with 
borax,  a  fait  of  fparing  folubility  is  formed,  which  is  the  borate 
of  lime. 

Borax  is  ufed  as  an  excellent  flux  in  docimaflick  operations. 
It  enters  into  the  compofition  of  reducing  fluxes,  and  is  of  the 
greateft  ufe  in  analyfes  by  the  blow-pipe.  It  may  be  applieil 
with  advantage  in  glafs  manufaOories  ;  for  when  the  fufion 
Curns  out  bad,  a  fmall  quantity  of  borax  re-eftablifhes  it.  It  is 
piore  efpeciaily  ufed  in  foldering.  It  aflilts  the  fufion  of  the 
folder,  caufes  it  to  flow,  and  keeps  the  furface  of  the  metals  in  a 
foft  or  clean  ftate,  which  facilitates  the  operation.  It  is  fcarce- 
ly  of  any  ufe  in  medicine.  Sedative  fait  alone  is  ufed  by  feme 
phyficians  •,  and  its  name  fufHciently  indicates  its  application. 

Borax  has  the  inconvenience  of  fwelling  up,  and  requires  the 
greateft  attention  on  the  part  of  the  artifi:  who  ufes  it  in  delicate 
works,  more  efpeciaily  \yhen  defigns  are  formed  with  gold  of 
difi^erent  colours.  It  has  been  a  long  defideratum  to  fubfl-itute 
fome  compofition  in  the  room  pf  borax,  which  might  poflefs  its 
advantages  without  its  defecfls. 

Mr.  Georgi  has  pubfilhed  the  following  procefs  : — «  Natron^ 
mixed  with  marine  fait  and  Glauber's  fait,  is  to  be  diflblved  hi 
lime-water  ;  and  the  cry  dais  which  feparate  by  the  cooling  of 
the  fluid  may  be  fet  apart.  The  lixivium  of  natron  is  then 
to  be  evaporated  ;  and  this  fait  afterwards  diflblved  in  milk. 
The  evaporation  aflbrds  fcarcely  one  eighth  of  the  natron  em- 
ployed, and  the  refidue  may  be  applied  to  the  fame  ufes  as 
t>orax," 


P74  S^afe  of  jimmoniach 

MefJrs.  Struve  and  Exchaquet  have  proved  that  the  phofphate 
of  pot-afli,  fufcd  with  a  certain  quantity  of  fulphate  of  lime, 
forms  an  excellent  glafs  for  foldering  metals. — See  the  Journal 
4e  Phyfique,  t.  xxix.  p.  78,  7^. 


ARTICLE  III. 
Borate  of  Ammoniack. 

This  fait  is  ftill  little  known.  We  are  indebted  to  Mr.  E^a 
f  ourcroy  for  the  following  indications  : — -He  diflblved  the  acid 
of  borax  in  ammoniack,  and  obtained  by  evaporation  a  bed  or 
plate  of  cryftals  connected  together,  whofe  furface  exhibited 
polyhedral  pyramids.  This  fait  has  a  penetrating  and  urinous 
tafte  J  it  renders  the  fyrup  of  violets  green  ;  gradually  lofes  its 
cryftailine  form,  and  becomes  of  a  brown  colour,  by  the  conta£l 
of  air.  It  appears  to  be  of  confiderable  folubility  m,  water* 
lime  difengages  the  volatile  alkali* 


PART  THE  SEGONt). 


CONCERNING  LITHOLOGY ;   OR   AN  ACCOUNT  Of 
STONY  SUBSTANCES. 


INTRODUCTION. 


J.  HE  objeiS  oi  Lithology  confifts   in   the  ftudy  of 
-Hones  and  earths. 

It  is  generally  agreed  to  call  thofe  fubftances  by  the  name  of 
Earth  or  Stone,  which  are  dry,  brittle,  inodorous,  infipid,  fcarce- 
ly  or  not  at  all  foluble  in  water,  and  of  a  fpecifick  gravity  not 
.exceeding  4,5. 

There  is  no  one  who  has  ferioufly  attended  to  the  ftudy  of 
lithology,  without  being  at  the  fame  time  aware  of  the  necellity 
of  eftablifbing  divifions  to  facilitate  the  knowledge  of  ftones, 
and  to  remove  the  numberlefs  difficulties  which  would  otherwife 
oppofe  the  acquifition  of  that  knowledge. 

It  is  an  obvious  difference  between  living  creatures  and  the 

f ubje£ls , of  the  mineral  kingdom,  that  thefe  laft  are  continually 

-•modified  by  external  caufes,  fuch  as  air,  water,  fire,  &c.   while 

the  former,  being  animated  and  governed  by  an  internal  force, 

'.pofTefs  charaf^ers  of  a  more  definite  and  unchangeable  nature^ 

.  The  forms  of  thefe  depend  upon  their  organization  ;    and,    in 

::geii^ral,  the  proceedings  of  nature  refpeding  them  are  more  con- 

Ttant,  and  better  afcertained. 

The  earthy  element  appears  to  be  paffive  of  itfelf  ;    it  is  obe- 
dient only  to  the  laws  of  inanimate  bodies  -,    and  we    may  refer 
sail  the  phenomena  of  formation  or  decompofition,  which  a  (tons 
is  fufceptible  of,   to  the  mere  law  of  affinities. 

This,  no  doubt,  is  the  caufe  of  that  variety  of  forms,  and  that 
mixture  of  principles,  which  fcarcely  permit  the  naturaliil  to  ef- 
tablifiv  his  fyftem  upon  fixed  bafes,  or  to  found  it  upon  conitant 
anil  invariable  charadfers. 

If  we  lake  a  view  of  the  proceedings  of  all  the  naturalifts 
who  have  hitherto  written,  we  mav  eaCIy  reduce  them  to  three 
da  (lie. 


I 


17^  On  the  Clajfificatioti 

1.  The  firft  clafs,  carried  by  the  imagination  alone  to  thzi 
epocha  when  this  globe  ifTued  from  the  hands  of  the  Creator^ 
have  followed  the  actions  of  the  various  deftructive  agents 
which  alter  or  overturn  its  furface.  In  this  way  they  have  fliewn 
us  the  various  rocks  fucceffively  depofited  or  placed  upon  the 
primitive  gloJDe  ;  and,  by  furveying  the  great  phenomena  which 
have  happened  upon  our  planet,  they  have  acquired  ideas  more 
or  lefs  accurate  refpe£ting  the  vaft  works  of  decompofition  and 
formation. 

2.  Others  have  bufied  themfelves  in  enquiring,  by  analyfiSj 
what  are  the  earths  or  primitive  matters  out  of  which  all  the 
ftones  we  are  acquainted  with  are  compofed.  This  clafs  of  phi- 
loPjphers  have  fupplied  ur>  with  the  mod  valuable  acquifitions 
refpecling  the  nature,  the  ufes,  and  the  decompofitions  of  thefe 
fubftances :  but  the  refults  of  analyfis,  though  neceflary  in  ac- 
quiring acciirate  ilotibns  of  each  ftone,  ar^  not  of  themfelves 
fufficient  to  form  the  bafis  of  a  method  of  claffing  -,  bccaufc 
thefe  characters  are  too  difficult  to  be  acquired,  and  at  molt  can 
be  only  ufed  as  fupplementary  rn  the  eltabliflimentof  fuch  other 
methods  as  may  be  employed. 

3.  Almoft  all  the  fyftems  of  clafhfication  hitherto  adopted, 
are  founded  upan  th6  external  characters  of   earthy  fubPiances. 

Some  naturalifts  have  fought,  in  the  variety  of  forms  exhibit- 
ed by  the  produ(5lions  of  the  mineral  kingdom,  fuch  principles  of 
divifion  as  to  them  appeared  fufficient.  But  not  to  mention 
that  the  fame  form  frequently  obtains  in  very  different  ftones, 
this  character  is  rarely  found,  and  \^'e  are  ignorant  of  the  cryf- 
taliization  of  moll  of  the  known  earths  :  the  cryftalUzation  can- 
not therefore  be  confidered  but  as  an  acceflary  or  fecondary  cir- 
eum  (lance. 

Other  naturalifts  have  eftabliflied  the^r  divifions  upon  certain 
properties  eafy  to  be  afcertained,  fuch  as  that  of  cffervefcing 
with  acids,  giving  fire  with  the  fteel,  &c.  But  thefe  characters 
do  not  appear  to  be  fufficiently  {triCt,  nor  fufficiently  exclufive  ; 
for  nothing  is  more  common  than  to  find  a  mixture  of  the  frag- 
ments of  primitive  rocks  with  thofe  of  calcareous  ftones.  Our 
province  exhibits  examples  of  this  every  ftep  we  take  -,  and 
thefe  mixtures  hardened  by  time,  poflefs  both  the  forementioned 
characters.  There  are  alfo  ftones  which,  without  changing 
their  nature,  give  fire  with  the  fteel,  or  effervefce  with  acids, 
accordingly  as  they  are  more  or  lefs  divided.  Such  is  the  laprs 
kzuli,  which  effervefces  when  pulverized,  but  ftrikes  fire  when 
in  the  mafs;  the  llate  likewifc  effervefces  when  in  powder,  but 
not  in  the  mafs.  Tlie  clalTification,  therefore,  which  is  founded 
on  thefe  characters,  is  not  rigorous,  and  may  at  the  moftbe  made 
«tv'  of  in  conjunction  with  others. 


cf  Earths  and  St  ones,  fj^ 

M.  D*Auberiton  is  the  naturalift  who  appears  to  me  to  have 
dilhibured  mineral  fubftances  with  the  greateft  order  of  any  who 
has  hitherto  undertaken  that  talk;  every  thing  which  he  fays 
on  this  fubjecl  (liews  the  experienced  eye  of  the  obferver  ;  and 
he  has  drawn  from  the  external  charaiflers  of  bodies  all  the 
charaders  polTible  to  be  had  from  that  fource.  But  he  could 
not  avoid  the  defeats  which  necelTarily  accompany  the  princi- 
ples on  which  he  has  founded  his  fyllem. 

Deeply  impreflcd  with  a  fenfe  of  the  infufEciency  of  thefe 
methods,  as  well  of  the  flight  opportunities  I  have  pofTefled  of 
improving  tltfem,  my  endeavours  have  been  exerted  in  coIle£ling 
together  all  the  charadlers  which  are  capable  of  affording  any 
ufeful  indications.  In  this  purfuit,  I  have  joined  the  charac- 
ters of  the  naturalift  to  thofe  of  the  chemift  ;  and  though  the 
method  which  I  have  adopted  be  very  far  from  that  degree  of 
perfeftion  which  might  be  defired,  I  neverthelefs  prefent  it  to 
the  publick  with  confidence.  It  differs  but  little  from  that  fol- 
lowed by  Meffrs.  Bergmann  and  Kirwart  ;  a  circumftance  which 
at  lead  affords  a  prejudice  in  its  favour.  The  peculiar  advanta- 
ges which,  in  my  opiniori,  it  appears  to  poffefs,  are — i.  The 
lithologick  produtTlions  are  diftributed  equally,  and  into  three 
claffes.  2.  All  the  analogous  produ6Vions  are  brought  together, 
and  arranged  as  it  were  in  a  natural  order.  In  a  word,  this  fyftem 
has  fixed  my  own  ideas  in  the  mofb  precife  manner ;  and  this 
has  more  particularly  induced  me  to  propofe  it  to  the  publick.* 

The  various  earths  beneath  our  feet  are,  in  general,  combina- 
tions ;  and  chemifts,  by  decompofing  thefe  fubftances,  have  fuc- 
cceded  in  obtaining,  in  the  laft  analyfis,  principles  which  may 
be  confidered  as  earthy  elements,  until  fubfequent  acquifitions 
ihall  either  confirm  or  deftroy  our  ideas  on  this  fubjecl. 

*  I  ccnGder  what  is  here  publiflied  refpe(Sling  Liihology  as  a  (Imple  and 
fliort  fketch  of  the  principles  which  I  explain  in  my  I-edlurcs.  It  wowld  be 
judging  me  with  too  mac|j  fevcrity,  if  the  reader  were  to  fuppofe  that  my 
prefent  deflgn  is  to  exhibit  a  complete  perforniance. 

A  more  intimate  acquaintance  with  this  ftjbjetJl  may  be  obtained  by  the 
pcrufal  of  the  following  works  : 

1.  EfTai  d'un  Art  de  Fufion  a  I'Aide  de  I'Air  Vital,  par  Erhmann.  Me- 
moiresdc  M.  Lavoifier  fur  le  m6me  fujet. — Memoirs  dt  M.  D'Arcet,  f'lr  I'Ac- 
tion  d'uu  Feu  egal,  violent,  et  continu,  fur  un  grand  nombre  de  Terres,  Pi- 
crres,  &c. 

2.  The  works  of  Margraffand  Pott,  more  efpecially  the  Lithogeogpcfie  of 
the  i:^tter. 

;;.  l.es  Pefanteurs  Sp^cifiquea  des  Corps,  per  M.  Briffbn. 

4.  Elenjcnts  of  Mineralogy,  by  Mr.  Kirwan. 

5.  Le  Manuel  due  Mlacralogifte  de  liergmann,  cnrichi  de  Notes  par  7,1, 
Tahbe  Mongez. 

6.  l.a  Muicralogie  de  M.  Sage. 

r.  Les  Ouvrages  fur  la  Chryftallograpliie  de  M.Rome  deLiHe,  de  M.  I'Abbt 
Hauy,  &c. 

y 


1 78  Ltme^  or  Calcareous  Earth, 

The  earthy  elements  mod  extenfively  diftributed  are  five  iiT 
number  ;  namely,  Lime,  Magnefia,  Barytes,  Alumine  andSilex. 

We  (liall  not  treat  of  the  other  primitive  earths  announced  by 
Mr.  Klaproth,  in  the  adamantine  fpar,  and  in  the  jargon  of  Cey- 
lon, becaufe  they  are  yet  too  flightly  known  and  too  fcarce,  to 
have  any  influence  upon  our  prefent  divifion. 

Nature  appears  to  have  formed  all  the  mixtures  and  combina- 
tions vi'hich  conftitute  ftones,  out  of  the  primitive  earths  here 
fpoken  of. 

If  we  dire£l  our  attention  to  the  nature  of  thefe  mixtures  and 
combinations,  we  (hall  diftinguifli  three  habitudes,  or  modes, 
which  eftabiifh  three  grand  divifions.  We  (hall  immediately  per- 
ceive that  thefe  earths  are,in  fome  in  (lances,  combined  with  acidsy 
which  form  faline  (tones  ;  that  in  other  in(bances  they  are  mixed 
with  each  other,  and  form  (lones  properly  fo  called,  and  that  in 
other  inftances  again,  thefe  (tones  fo  formed  by  the  mixture  of 
primitive  earths,  are  united  tog^her,  or  fixed  in  a  gluten  or 
cement,    vrhich  forms  rocks,  pebbles,  or  compound  (tones. 

We  ftiall  therefore  diftingui(h  three  clafTes  in  Lithology  :  the 
fird  will  comprehend  faline  (tones  ;  the  fecond  (tones,  properly 
fo  called,  or  earthy  mixtures  5  and  the  third  rocks,  or  (tony  ad- 
mixtures. 

We  confider  it  as  indifpenfably  necelTary  to  explain  the  nature 
of  the  primitive  earths,  before  we  can  proceed  to  treat  of  their 
combinations. 

I.    Lime. 

This  earth  has  been  found  totally  difengaged  from  all  combi- 
nation, near  Bath. — See  Falconer  on  the  Bath  Waters,  vol.  i.  p. 
156  and  1 5  7.  But  as  this  Is  perhaps  the  only  obfervation  of  the 
kind  which  we  polTefs,  it  is  indifpenfably  nece(rary  to  (hew  the 
procefs  by  which  lime  may  be  obtained  in  a  (tate  of  the  greateft 
purity. 

For  this  purpofe  chalk  is  to  be  wafhed  in  boiling  dlftilled  wa- 
ter, then  dilTolved  in  diftilled  acetous  acid,  and  precipitated  by 
the  carbonate  of  ammoniack,  or  mild  volatile  alkali.  The  pre- 
cipitate, being  waflied  and  calcined,  is  pure  lime. 

This  earth  polTefles  the  following  charadters  : 

8.  La  Tableau  Methodiqne  des  Mineraux,  par  M.  D'Aiibenton. 

9.  La  Mineralngic  de  M.  le  Corate  de  BufFon  ;  in  which  that  celebrated 
writer  has  coUedbcJ  a  great  number  of  valuable  fads,  whofe  merit  is  inde- 
pendent of  all  theory. 

10.  The  Mincralogical  Works  of  Meflrs.  Jars,  Dietrich,  de  Born,  Ferber, 
Ti-ebra,  Pallas,  Gmelin,  Linne,  Dolomieu  de  SaufTure  de  la  Peroule,  &c. 

1 1.  The  excellent  Analylesof  Stones,  publiflied  from  time  to  time  by  Pott, 
Margraff,  Bayen,  Bergraann,  Gerard,  Schtele,  Achard,  Mongez,  &c. 


*   BafytiSy   or  Ponderous  Earths*  179 

T.  It  is  foluble  in  fix  hundred  and  eighty  times  its  weight  of 
water,  at  the  temperature  of  fixty  degrees  of  Fahrenheit.  Kirwan. 

2.  It  has  a  penetrating,  acrid,  and  burning  tafte. 

3.  Its  fpecifick  gravity  is  about  2,3  according  to  Kirwan,  and 
2,720  according  lo  JBergmann. 

4.  It  feizes  water  with  great  avidity  •,  at  the  fame  time  that 
it  falls  into  powder,  increafes  in  biflk,  and  emits  heat. 

5.  Acids  diflblved  it  without  efFervefcence,  but  with  the  pro- 
duclion  of  heat. 

6.  The  borate  of  foda,  or  borax,  the  oxides  of  lead,  and  the 
^hofphates  of  urine,  diffblve  it  by  the  blow-pipe  without  effer- 
vefccnce. 

It  appears  to  be  infufible  alone,  as  it  has  refifted  the  heat  of 
flame  urged  by  a  flream  of  .vital  air. — See  the  Memoir  of  Mr. 
Lavoifter. 

When  it  is  mixed  with  acids,  it  forms  a  fulible  combination  j 
and  it  haftens  the  fufion  of  aluminous,  filiceous,  and  magnefian 
earths,  according  to  the  experiments  cf  Meflrs.  Darcet  and 
Jergmann. 

II.  Barytas,  or  Pondrous  Earth. 

We  are  indebted  to  the  celebrated  chemifts  Galin,  Scheele, 
and  Bergmann  for  our  knowledge  of  this  earth. 

It  has  not  yet  been  found  exempted  from  all  combination  ; 
but  in  order  to  obtain  it  in  a  fuitable  degree  of  purity,  the  fol- 
lowing procefs  may  be  ufed  : 

The  fulphate  of  barytes,  or  ponderous  fpar,  which  is  the  moft 
ufual  combination  met  with  on  the  eirth,  is  to  be  pulverized, 
and  calcined  in  a  crucible,  with  an  eighth  part  of  powder  of 
charcoal :  the  crucible  muft  be  kept  ignited  during  an  hour  ; 
after  which  the  calcined  matter  is  to  be  thrown  into  water  : 
it  communicates  a  yellow  colour  to  this  fluid,  at  the  fame  time 
that  a  ftrong  fmell  of  hepatick  gas  is  emitted  ;  the  water  is  then 
to  be  filtered,  and  muriatick  acid  poured  in  :  a  confiderable 
precipitate  falls  down,  which  muft  be  feparated  from  the  fluid 
by  filtration.  The  water  which  pafl^es  through  the  filter  holds 
the  muriate  of  barytes,  or  marine  fait  of  ponderous  earth,  in 
folution.  The  carbonate  of  pot-afli,  or  mild  vegetable  alkali, 
in  folution,  being  then  added,  the  ponderous  earth  falls  down, 
in  combination  with  the  carbonick  acid  ;  and  this  lafl  principle 
may  be  driven  off  by  calcination. 

1.  Pure  barytes  is  of  a  pulverulent  form,  and  extremely  white. 

2.  It  is  foluble  in  about  nine  hundred  times  its  weight  of  dif- 
tilled  water,  at  the  temperature  of  fixty  degrees,  according  to 
Kirwan. 


l8o  Magnsjtan  Earth,      Pure  CMy» 

3.  The  Prufiiate  of  pot-afh,  or  Pruffian  alkali,  precipitates  it 
from  its  combination  with  xhp  nitrick  and  muriatick  acids. 
This  habitude  di{tingut(hes  it  from  other  earths.-~-See  Kirwan. 

4.  It  precipitates  alkalis  from   their  combinations  with  acids, 

5.  Barytes  expofed,  by  Mr.  Lavoifier,  to  flame  fed  with  oxi- 
genous  gas,  was  fufed  in  a  few  feconds  :  it  extended  itfelf  upon 
the  furface  of  the  coal ;  after  which  it  began  to  burn  and  detq- 
Uate  until  the  whole  was  nearly  diflipated.  This  kind  of  inflam- 
mation is  a  charafter  common  to  metallick  fubftances  ;  but 
xvhen  the  barytes  is  pure  it  is  perfe^lly  infufibie. — See  Lavoifier. 

Ponderous  earth  urged  by  the  blow-pipe  makes  little  effervef- 
cence  with  foda,  but  is  perceptibly  diminiilied  :  it  difiblves  in  the 
borate  of  foda  with  efl^ervefcence,  and  ftill  more  with  the  phof- 
phates  of  urine. — See  the  abbeMongez,  Manuel  duMii^ralogifte. 

6.  Its  fpecifick  gravity  exceeds  4,000,  according  tcJyCirwan. 

III.  Magnefia,  or  Magnefian  Earth.  . 

This  earth  has  been  no  where  found  difengaged  from  ^11  for- 
eign fubftances  j  bat  in  order  to  obtain  it  in  the  utmoft  poffible 
ftate  of  purity,  the  cryftals  of  the  fulphate  of  magneha,  or  Ep- 
fom  fait,  are  to  be  diflblved  in  diftilled  water,  and  decompofed 
by  the  carbonate  of  alkali.  The  precipitate  muft  then  be  cal- 
cined, to  difengage  the  carbonick  acid. 

1 .  Pure  magnefia  is  very  white,  very  friable,  and,  a$  it  were, 
fpongy, 

2.  Its  fpecifick  gravity  is  about  2,33,  according  to  Kirwan. 

3.  It  is  not  perceptibly  foluble  in  water  when  pure  ;  but  when 
it  is  combined  with  the  carbonick  acid,  it  is  foluble  *,  and  cold 
water  has  a  ftronger  adion  on  it  than  hot,  according  to  the  Ca-^ 
periments  of  Mr.  Butini. 

4.  It  has  no  perceptible  adion  on  the  tongue. 

5.  It  flighily  converts  the  tindlure  of  turnfole  to  green. 

6.  Mr.  Darfet  has  obferved,  that  a  ftrong  heat  agglutinates 
it  more  or  lefs  ;  but  Mefirs.  De  Morveau,  Butini,  and  Kirwan, 
found  that  it  was  not  fufible  ;  and  the  experiments  of  Mr.  La- 
voifier have  proved  that  it  is  as  infufibie  as  barytes  and  lime. 

The  borate  of  foda,  and  the  phofphates  of  urine,  diifolve  it 
with  effervefcence. — See  the  abbe  Mongez. 

IV.  Alumine,  or  Pure  Clay. 
This  earth  is  not  more  exempt  from  mixture  and  combination 
than  the  foregoing  ;  and  in  order  to  obtain  it  in  a  ftate  of  puri- 
ty, the  fulphate  of  alumine  is  diflblvcd  in  water,  and  decompof- 
ed by  elfcrvefcent  alkahs. 


Silcxy  or  Viirifable  Earth.  \%i 


1.  Pure  clay  feizes  water  with  avidity,  and  may  then  be 
kneaded.     It  adheres  ftrongly  to  the  tongue. 

2.  Its  fpeciiick  gravity  does  not  exceed  2,000,  according  to 
Kir  wan. 

3.  When  expofed  to  heat,  it  dries,  contracts,  ilirinks,  and  be- 
comes full  of  clefts.  A  confuierable  degree  of  heat  renders  it 
fo  hard  that  it  gives  fire  with  the  fteel. 

When  it  has  been  well  baked,  it  is  no  longer  capable  of  unit- 
ing with  water  ;  but  requires  to  be  difiolved  in  an  acid,  and  pre- 
cipitated,   in  order  that  it  may  relume  this  property. 

The  experiments  of  Mr'.  Lu voider  (liew  that  pure  alumine  is 
capable  of  an  imperfe(5l  fufion,:  "approaching  to  the  confiltence 
of  pafte,  by  heat  excited  by  a  current  of  vital  air.  It  is  then 
transformed' into  a  kind  of  very  liard  ftonc,  which  cuts  glafs  like 
the  precious  (tones,  and  which  very  difficultly  yields  to  the  file. 

The  mixtureof  chalk  fingularlyaflifts  the  fufion  of  this  earth  : 
it  is  fufible  in  a  crucible  of  chalk,  according  to  Mr.  Gerhard, 
but  not  in  a  crucible  of  clay. 

The  borate  of  foda,  and  the  phofphates  of  lime,  diUblve  It. — i 
See  Kir  wan  and  the  abbe  Mongez. 

According  to  the  experiments  of  Mr.  Dorthes,  the  purefl  na- 
tive clays,  and  even  that  which  is  precipitated  from  alum,  con- 
tain a  fmall  quantity  of  iron  in  the  date  of  oxide  ;  ahdit  is  from 
this  principle  that  the  earthy  fmell  which  is  emitted  by  moifteri- 
cd  clays,  arifes  :  it  is  very  difficult  to  deprive  them  of  it. 

V.  Silex,  or  Quartzofe  Earth,  Vitrifiable  Earth,  &c, 

This  earth  exifts  nearly  in  a  ftate  of  purity  in  rock  cryflal.  But 
%j/hen  it  is  required  to  be  had  in  a  (late  of  purity  free  from  all 
fufpicion,  one  part  of  fine  rock  cryftal  may  be  futed  with  four 
of  pure  alkali.  The  fufed  mafs  mud  then  be  diOblved  in  water, 
and  precipitated  by  an  excefs  of  acid. 

1.  Pure  filex  polTefies  a  fingular  degree  of  roughnefs  and  af- 
perity  to  the  touch.  It  is  abfolutely  void  of  all  difpofition  to  ad- 
here ;  and  its  particles,  when  agitated  in  water,  fall  down  with 
extreme  facility. 

2.  Its  fpecifick  gravity  is  2,65 

3.  Bergmann  had  affirmed  that  water  might  dlHolve  it  ;  and 
Mr.  Kir  wan  has  pretended  th^t  10,000  parts  of  water  might- 
hold  one  of  filex  in  folution,  at  the  ordinary  temperature  of  the 
atmofphere  ;  and  might  even  take  up  a  greater  quantity  at  a 
higher  temperature. 

The  fluoiick  acid  diilblvcs  it ;  and  lets  it  fall  when  it  comes 
jn  contact  with  water,  or  when  it  \i  confiucrably  cooly'd. 


*82  Cafcanous  Saline  Stoufs, 

5.  Alkalis  diflblve  it  in  the  dry  way,  and  form  glafs  ;  but 
they  attack  it  likewife  in  humid  way,  and  are  capable  of  diffaiv- 
ing  one  fixth  part  of  their  weight  when  it  is  in  a  Itate  of  extreme 
divifion. 

6.  The  burning  mirror  does  not  fufe  it  ;  but  a  current  of  vi^ 
tal  air  produced  a  commencement  of  fufion  on  its  furface. — Sec 
Lavoifier. 

Before  the  blow-pipe  foda  diflblves  it  with  efFervefence.  The 
borate  of  foda  diflblves  it  flowly,  and  without  ebulUtion. 


CLASS       I. 

Concerning  the  Combination  of  Earths  with  Acids.  ^? 

This  clafs,  which  comprehends  the  combination  of  primitive 
earths  with  acids,  naturally  exhibits  five  genera. 

GENUS       I, 

Earthy  Salts  with  Bafts  of  Lime. 

The  combination  of  lime  with  various  acids  affords  the  feverif 
al  fpecies  of  calcareous  falts  comprehended  in  this  genus. 

•SPECIES       I. 
Carbonate  of  Lime,  or  Calcareous  Stone. 

The  combination  of  lime  with  the  carbonick  acid  is  very  com- 
monly met  with,  and  conciprehends  all  the  ftones  which  have 
hitherto  been  dillinguilhed  under  the  names  of  lime-ftone,  cal- 
careous ftone,  Sec. 

The  charadlers  of  the  carbonates  of  lime  are — i;  They  ef- 
fervefce  with  certain  acids.  2.  They  are  converted  into  lime 
by  calcination. 

The  formation  of  thefe  ftones  appears  to  us  to  be  for  the 
n^oft  part,  owing  to  the  wearing  down  of  fliells.  The  identity 
of  the  conftituent  principles  of  Ihells  and  calcareous  ftones,  and 
the  prefence  of  thefe  fame  fhells,  more  or  lefs  altered,  in  the 
lime-ftone  mountains,  authorize  us  to  conclude  that  a  great 
part  at  leaft  of  the  calcareous  mafs  of  our  globe  owes  its  origin 
to  this  caufe  only. 

Though  our  imagination  appears  to  aflent  with  difhculty  in 
referring  effe£ls  of  fo  wonderfully  extenfive  a  nature  to  a  caufe 


Cr^Jlallized  Calcareous  Stones,  183; 

apparently  fo  weak,  we  are  compelled  to  admit  it  when  we  take 
a  flight  view  of  the  known  hiftory  of  fhells. 

In  fa£l;,  we  obferve  the  numerous  clafs  of  (hell  animals 
which  poflefs  this  (lony  covering  almoft  at  the  inflant  of  their 
origin.  We  fee  it  infenfibly  become  thick  and  enlarged  by  the 
appofition  of  new  coverings  ;  and  this  (hell  at  length  comes  to 
occupy  a  volume  fifty  or  fixty  times  larger  than  that  of  the  ani- 
mal which  produced  it.  Let  us  confider  the  prodigious  num- 
ber of  animals  that  emit  this  flony  tranfudation  ;  let  us  attend 
to  their  fpeedy  augmentation,  their  multiplication,  and  the  fhort 
period  of  their  life,  the  mean  term  of  which  is  about  ttxi  years, 
according  to  the  calculation  of  the  celebrated  BufFon  ;  let  us 
multiply  the  number  of  thefe  animals  by  the  mafs  of  fliell  they 
leave  behind  them — and  we  fhall  then  arrive  at  the  mafs  which 
the  fhells  of  one  fingle  generation  ought  to  form  upon  this 
globe.  If  we  proceed  further  to  confider  how  many  genera-* 
tions  are  extindt,  and  how  many  fpecies  are  loft,  we  fliall  be  no 
longer  furprized  to  find  that  a  confiderable  part  of  the  furface 
of  the  globe  is  covered  with  their  remains. 

It  may  eafrly  be  conceived  that  thefe  fhells  when  carried 
along  by  currents  of  water,  muft  ftrike  together  and  wear  their 
refpe£live  furfaces  ;  and  that  their  pulverulent  remains,  after 
being  long  carried  about  and  fufpended  by  the  waters,  mufl:  at 
lad  fubfide,  and  form  heaps  or  banks  of  fhells,  more  or  lefs  al- 
tered according  to  circumftances. 

But  whatever  may  be  admitted  as  the  origin  of  this  ftone,  it 
is  found  to  exifl:  in  two  principal  ftates  \  that  is  to  fay,  either 
in  the  form  of  cryflals,  or  of  irregular  mailes. 

I.  Cryflallized  Calcareous  Stones. 

A  concurrence  of  circumftances  which  very  feldom  meet  to- 
gether, is  required,  in  order  that  cryftaUization  may  take  place. 
This  is  doubtless,  the  reafon  why  fpars  and  calcareous  cryftals 
compofe  the  fmallefl  part  of  this  genus.  The  cryflals  are 
found  in  cavities  of  calcareous  mountains  ;  in  the  clefts  which 
penetrate  into  the  internal  part  of  flones  of  this  clafs  ;  and  gen- 
erally in  all  places  where  waters  find  accefs,  after  having  worn 
down  calcareous  ftone  to  a  ftate  of  extreme  attenuation,  nearly 
correfpondent  to  folution. 

Calcareous  ftone,  in  its  cryftallized  ftate,  prefents  us  with 
feveral  varieties  of  form  ;  but  the  rhomboidal  figure  appears  to 
be  the  moft  conftant  and  the  moft  general.  The  environs  of 
Alais  abound  with  rhomboidal  fpars  of  the  greatcft  beauty  \ 
they  are  tranfparent  like  thofe  of  Iceland,  and  double  objeds  in 
tlie  fame  manner. 


384  Calcareous  Stones  not  Crvfallrled* 

It  often  happens  that  a  group  of  rhomboidal  cryftals  exhrbitS 
at  its  furface  a  number  of  pyramids  more  or  lels  prominent j 
which  confift  of  t]ie  angles  of  rhomboids  of  different  degrees  of 
length.  It  cannot  but  be  admitted,  with  Mr.  Rome  de  LiOe, 
that  the  pyramiidal  form  is  a  flight  modification  of  the  rhom- 
boid •,  for  if  a  pyramid  of  fpar  be  broken,  it  is  reduced  into  ele- 
ments of  a  rhomboidal  figure. 

The  principal  varieties  of  the  pyramidal  form  are  deduced 
more  elpecially  from  the  number  of  their  fides  ;  and  when  the 
pyramid  is  long  and  flrarp,  it  is  called  dog-tooth  fpar,  or  hog- 
tooth  fpar. 

Calcareous  ftones  often  afFetl  the  p^rifmatick  form  ;  and  this  is 
likewife  attended  with  fome  varieties. 

The  prifm  is  frequently  fix-flded  and  truncated  ;  fometimes 
it  is  terminated  by  a  trihedral  pyramid  ;  and  when  the  prifm  is 
very  fhort,  and  its  fummit  is  aimoil  entirely  In  conra<^  with  the 
ground,  the  cryflai  is  known  by  the  name  of  Lenticular  Spar. 

All  the  varieties  of  form  which  cryftallized  calcareous  ftones 
have  hitherto  prefented,  may  be  feen  in  the  Cryftallography 
of  Mr.  Rome  de  Li  fie. 

The  fpecifick  gravity  of  calcareous  fpars  is  about  2.700 
when  pure,  according  to  Kirwan. 

They  contain  from  thirty-four  to  thirty-fix  parts  of  carbonick 
acid,  and  from  fifty-three  tofiFty-five  of  earth  ;  the  reft  is  water. 
— See  iCiirwan. 

Spars  often  exhibit  a  fmooth  uniform  fu?face,  upon  which 
the  fulphurick  acid  takes  bat  flight  hold  :  they  are  fometimes 
contaminated  with  iron,  which  gives  them  Various  tinges. 

JI.  Calcareoas  Stones  which  are  not  cryftallized. 

Few  calcareous  ftones  aft'e^t  any  regular  form  :  they  lie  al- 
moft  always  in  ftrata,  or  immenfe  blocks  thrown  or  heaped  to- 
gether on  the  furface  of  the  globe,  in  which  we  cannot  reafon- 
ably  pretend  to  difcern  any  primitive  defign  of  cryftallization. 
The  notion  itfelf  which  we  have  of  the  form.a.tion  of  thefe 
mountains,  and  the  ftratified  difpontion  of  their  parts,  does  not 
•allow  us  to  difcern  any  other  efFe£t  than  the  natural  confequence 
of  the  flowing  of  water,  which  muft  have  occafioned  a  contrac- 
tion, and  difpofed  the  rocks  in  ftrata  or  beds. 

It  feems  to  me  that  two  very  natural  divifions  may  be  eftab- 
liftied  among  calcareous  ftones  which  are  not  cryftallized  :  for 
they  are  either  fufceptible  of  a  perfefl  polifli,  in  which  cafe  they 
are  called  marbles  and  aiabafters  ;  or  they  are  not  fufceptible 
of  this  polifti,  in  which  cafe  they  are  called  friable  earths,  tufa, 
&c. 


Calcareous  Stones,      Marble,  1 8^ 

A.    Calcareous  ftones  fufceptible  of  a  perfe£l  polifli. 

Although  it  be  proved  from  the  experiments  of  chemifts,  and 
more  efpecially  from  thofe  of  Mr.  Bayen,  that  marbles  contaiu 
a  greater  or  lels  proportion  of  clay,  we  are  under  the  necefllty 
of  placing  them  here  :  becaufe  the  calcareous  earth  predomi- 
nates to  fuch  a  degree,  that  they  cannot  with  propriety  be  placed 
elfe where  j  and  becaufe  they  poflefs  all  the  characters  of  lime- 
ftone. 

Marbles  differ  from  other  calcareous  ftones  by  the  polifh  of 
which  they  are  fufceptible  ;  and  they  are  diftinguifhed  from  each 
other  by  their  colours. 

White  marble  is  ufually  the  pureft.  We  are  acquainted  with 
the  marble  of  Carrara,  and  the  ancient  ftatuary  marble  of  Paros. 

Black  marble  is  coloured  either  by  bitumen  or  by  iron.  Mr. 
Bayen  found  this  metal  in  the  proportion  of  five  parts  in  the 
hundred.     When  it  is  veined  by  pyrites,  it  is  called  Portor. 

There  are  an  infinite  number  of  varieties  of  coloured  marble. 
The  colouring  part  is  in  general  owing  to  the  alterations  of  the 
iron,  which  is  fometimes  obedient  to  the  magnet,  according; 
to  an  obfervation  of  Mr.  De  Lifle.  Blue  and  green  marbles  owe: 
their  colours  to  a  mixture  of  fchorle,  according  to  Rinmann  in 
his  Hiftory  of  Iron. 

The  marble  which  prefents  the  figure  of  (hells  appears  to  be 
formed  fimply  out  of  a  heap  of  fhells  connefted  by  a  calcareous 
cement  ;  it  is  known  by  the  name  of  LumachcUo.  That  o£ 
Bleyberg  in  Carinthia  forms  one  of  the  moft  beautiful  fpecies- 

The  marble  which  is  called  figured  marble,  exhibits  either 
traces  of  vegetables,  as  that  of  HefTe  ;  or  ruins  and  rocks,  like 
that  of  Florence.  The  dendrites  appear  to  be  formed  merely 
by  ferruginous  infiltrations  through  the  cracks  of  theie  ftones. 

Several  naturalifts  have  mentioned  flexible  marble.  Father  Jac- 
quier  defcribed  this  in  1764,  in  the  Gazette  Litteraire  ;  and  the 
abbe  De  Sauvages  has  communicated  to  the  Academy  of  Mont- 
pellier  a  defcription  of  the  plates  of  flexible  marble  which  are  in 
the  Palais  Burgeois. 

Alabafters  are  calcareous  (tones  of  the  nature  of  marble  ;  they 
appear  to  be  formed  like  the  ftala£lites,  and  are  fometimes  a- 
dorned  with  the  moft  beautiful  colours  :  thefe  in  general  pofl^efs 
a  certain  tranfparency,  with  a  ftratiform  texture  varioufly  col- 
oured, and  caufe  a  double  refraction  of  the  light  when  they  are 
fufiiciently  tranfparent.  In  the  treatife  of  Mr.  Briflbn  on  the 
fpecifick  gravity  of  bodies,  the  reader  will  find  the  refult  of  his 
valuable  experiments  on  that  of  marbles,  alabafters,  and  general- 
ly all  the  calcareous  ftones. 
Z 


iB6'  Calcareous  Stones. 

*■ 

B.  Calcareous  (lone  not  fufceptible  of  a  perfecH:  polifh. 

Calcareous  (tones  which  are  not  fufceptible  of  a  perfe<fl  polifh,* 
are  found  either  in  mafTes,  or  in  the  pulverulent  form  ;  which 
circumftance  will  aiford  a  foundation  for  our  natural  diftindion. 

1.  Solid  calcareous  ftone  is  in  general  the  ftone  ufed  for  build- 
ing ;  and  this  is  found  in  feveral  varieties,  diflering  in  finenefs 
of  grain,  porofitjr,  colour,  confidence,  or  weight  :  Thefe  arc 
gradations  which  eftablifh  the  feveral  qualities  of  ftones  ;  and 
are  the  caufe  why  one  hardens  in  the  air,  while  another  is  de- 
compofed.  On  thefe  feveral  accounts  it  is  that  the  refpe^tive 
varieties  are  applied  to  various  ufes  j  and  it  is  the  bufmefs  of  the 
Ikilful  artift  who  ufes  them  to  diftinguifh  their  qualities. 

In  the  number  of  thefe  ftones  ufed  for  building,  there  are  fome 
which  imbibe  and  retain  water,  in  confequence  of  which  they 
are  burll  or  crumbled  by  the  fro  ft  ;  whereas  others  fufFer  the 
water  which  they  originally  contained  to  efcape  and  become 
liarder  by  the  contact  of  the  air. 

2.  Calcareous  ftone  is  fometimes  found  in- the  pulverulent 
form.  Chalk  is  of  this  kind  ;  and  when  it  is  white,  and 
.very  finely  divided,  it  is  formed  into  thofe  mafles  known  in  com- 
merce by  the  name  of  Spanifti  White.  For  this  purpofe  it  is 
agitated  in  a  veflcl  with  water.  The  foreign  fubftances,  fuch 
as  flints,  pyrites,  &c.  are  precipitated  •,  the  water  is  then  decant^- 
ed  ;^  and  the  chalk,  which  is  held  fufpended,  very  foon  fubfides  : 
this  is  dried,  and  divided  into  long  fquare  pieces,  to  form  the 
Spanifti  Wiute. 

When  a  natutal  ftream  of  water  wears  away  this  chalk,  and 
afterwards  depofites  it,  the  refult  has  been  diftirtguifiied  by  the 
name  of  Gurrh  -,  and  when  this  pofTeiTes  a  certain  confiftence, 
arifmg  from  the  mixture  of  argillaceous  and  magnefiaii  earths,, 
it  is  diftinguiftied  by  the  name  of  Agarick  Mineral. 

As  calcareous  earth  is  fufceptible  of  extreme  dlvifion,  the  wa- 
ter which  wears  it  away,  and  is  afterwards  filtered  throu-gh  the 
clefts  in  rocks,  depofites  it  gradually,  and  forms  thofe  incrufta- 
tions  known  by  the  vulgar  under  the  name  of  Petrefadtions,  and 
by  that  of  Stalacfbites  among  Uc^tur^lifts. 

Thefe  calcareous  depofitions  very  frequently  preferve  the  form 
of  fuch  fubftances  as  they  have  covered,  and  prefent  figures  of 
mofs,  roots,  fruit,  &c.  which  has  given  rife  to  an  opinion  that 
thofe  fubftances  were  transformed  into  ftone. 

The  increafe  of  ftala£lites,  being  accompliflied  by  addition  to 
their  external  furfaces,  their  texture  exhibits  concen trick  coats 
of  different  fliades,  accordingly  as  the  water  may  have  been' 
charged  with  different  colouring  principles. 


'  Calcareous  Stones  1 8  J 

The  cavities  which  are  frequently  fouod  in  calcareous  moun- 
tains are  often  lined  with  flaladites  ;  and  thefe  grottos  form  one 
of  the  moft  flriking  appearances  which  can  prefent  itfelf  to  the 
eyes  of  the  naturalift. 

The  grandeur  of  thefe  fubteraneousplaces^the  abfence  of  light, 
the  feeble  glimmering  of  a  torch,  which  only  half  enlightens  the 
i"urrounding  objefts,  render  thefe  regions  gloomy,  majeftick, 
and  impofing.  The  multiplicity  of  figures,  the  variety  ot  forms, 
and  their  refemblance  to  other  objects,  never  fail  to  caufe  a  high 
degree  of  aftonilhment  in  the  mind  of  the  mineralogical  ftudent. 
Among  the  infinite  number  of  thefe  forms,  there  are  fome  which 
aie  very  agreeable,  fuch  as  the  flos  ferri,  cauliflowers,  lace,  or 
fringes.  Other  very  fmgular  figures  are  likewife  found,  fuch 
as  the  priapolithes,  pifolithes,  polithes,  &c. 

Mr.  Lougeon  of  Ganges  has  obferved,  iu  the  grotto  called 
Des  Demoifelles,  a  number  of  forms  fo  varied  and  ftrange,  as  to 
exhibit  a  very  altonilhing  collection. 

Thefe  tranfudations,  or  rather  thefe  ftony  depofitions,  have 
given  rife  to  a  belief  in  the  vegetation  of  ftones.  The  celebrat- 
ed Tournefort  was  of  opinion  that  he  had  obferved  nature  in  the 
very  fa61:,  in  the  famous  grotto  of  Antiparos,  where  he  faw  in- 
fcriptions  engraved  in  the  ftone,  but  afterwards  converted  into 
reliefs.  Baglivi  has  written  a  treatife  on  the  vegetation  of  ftones, 
in  which  he  cites  many  fa£ts  of  this  nature. 

All  the  world  is  acquainted  with  the  depofitions  of  the  fpring 
jn  the  vicinity  of  Clermont  ;  but  the  moit  furprizing  of  all  pet- 
jrefying  waters  is  that  of  Guancavelica  in  Peru.  Barba,  D.  Ulloa 
and  Frezier,  have  given  us  a  defcription  of  it.  Feuille  informs 
us  that  this  water  rifes  very  hot  in  the  middle  of  a  fquare  ba- 
fon,  and  becomes  petrefied  at  a  fmall  diftance  from  the  fpring. 
The  water  is  a  yellowifh  white,  and  the  incruftations  have  been 
ul'ed  to  build  the  houfes  of  Guancavelica.  The  workmen  fill 
moulds  with  its  water  and  fome  days  afterwards  they  find  them 
incrufted  with  this  ftone.  The  ftatuavies  expofe  their  moulds 
in  this  fpring,  and  have  only  to  give  the  polilh  in  order  to  ren- 
der their  ftatues  tranfparent.  All  the  ftatues  ufed  in  religious 
ceremonies,  by  the  catholicks  pf  Lima  are  of  this  fubftance, 
and  are  very  beautiful — Journal  des  Obfcrv.  torn.  i.  434. 

In  the  year  1760,  Mr.  Vegni  devifed  a  method  of  making  a 
fitnilar  ufe  of  the  very  v/hite  chalk  which  is  contained  in  the  wa- 
ters of  the  baths  of  St.  Philip  in  Tufcany.  .  For  this  purpofe  the 
water  is  fullered  to  run  for  the  fpace  of  near  a  mile,  in  order 
that  it  may  depofite  the  fulphur,  the  felenite,  and  the  tufa  which 
it  contains  ;  and  in  this  purified  ftate  it  is  ufed  in  the  fabrica- 
tion of  bas  reliefs.     It  is  introduced  at  the  roof  of  a   building, 


1 83  Fabrication  of  Lime, 

into  a  clofet  conflrufted  of  planks  fitted  together.  The  watei^ 
falls  from  twelve  to  fifteen  feet  in  height,  upon  a  wooden  crofs 
placed  on  a  poft  ;  by  which  fall  it  is  divided,  and  dafhes  late- 
rally againft  fulphur  moulds,  which  are  placed  on  the  fides  oi 
the  cabinet  In  this  way  it  depofites  the  particles  of  the  earth 
^hich  it  contained,  and  the  mould  becomes  filled.  Mr.  Vegni 
placed  the  moulds  upon  pieces  of  wood  which  are  moved  cir- 
cularly. This  alabafter  is  as  hard  as  marble  ;  and  the  incruf- 
tation  is  more  beautiful,  and  harder,  in  proportion  as  the  pofi- 
Xion  of  the  mould  is  more  vertical,  and  its  diftance  greater.        * 

The  Analyfis  and  Ufes  of  Calcareous  Stone. 

In  1755,  Dr.  Black  proved  that  calcareous  ftone  pofTefles,  as 
one  of  its  component  parts,  an  air  different  from  atmofphericlc 
:9ir.  He  aflerted  that  calcareous  ftone  when  deprived  of  this 
air  by  calcination,  forms  lime  ;  and  that  lime  might  again  pafs 
to  the  ftate  of  calcareous  ftone  by  refuming  the  principle  it  had 
teen  deprived  of.  In  1764,  Macbride  fupported  this  dodlrine 
by  new  fa6ls.  Jacquin  added  other  experiments  to  thefe  ;  and 
proved  that  lime  and  alkalis  owe  their  caufticity  to  the  fubtrac- 
tion  of  this  fixed  air,  at  the  fame  time  that  he  pointed  out  fev- 
cral  methods  of  depriving  them  of  it. 

The  procefles  which  are  moft  commonly  ufed  for  the  de« 
compofition  of  lirne-ftone,  are  fire  and  acids  ;  the  firft  is  ufed 
in  the  making  of  lime  ;  the  fecond  in  laboratories,  when  it  is 
intended  to  procure  the  carbonick  acid. 

In  order  to  form  lime,  the  calcareous  ftone  is  calcined  in  fur- 
naces, whofe  conftru61;ion  is  varied  according  to  the  nature  of 
l^e  oombuftibles  made  ufe  of. 

"When  pit-coal  is  ufed,  an  inverted  cone  is  conftru£\ed  of 
vitrifiable  ftone,  which  is  filled  by  alternate  ftrata  of  coai 
and  lime-ftone  ;  and  the  lime  is  taken  out,  after  the  operation, 
by  an  apertu,re  at  the  top.  In  proportion  as  the  mafs  fubfides, 
care  is  taken  to  fupply  the  furnace  at  the  top,  in  order  that  the 
flame  and  heat  may  not  be  loft. 

Bergmann  has  obferved  that  moft  fpecimens  of  calcareous 
ftone  which  become  black  or  brown  by  calcination,  contain 
inanganefe,  and  that  the  lime  v/hich  they  produce  is  excellent. 

According  to  Rinmann,  the  white  calcareous  ftones  which 
become  black  by  calcination,  contain  about  one  tenth  part  of 
this  fubftance. 

Calcination  deprives  lime-ftone  of  the  acid  and  water  which 
it  contained.  Thefe  two  principles  are  evidently  replaced  by  the 
rnatter  q^  heat  itfelf.     The  odoui:  of  $re  which  c^uick-Ume  emits  9 


)     Lime  Water  a?id  Lime.  1 8p 

the  light  which  it  afFords  when  flackened  in  a  dark  place  ;  the 
jcolour  which  it  communicates  to  the  lapis  caullicus ;  the  prop- 
erty which  it  pofTefles  of  producing  the  oxide  and  the  g]aireso£ 
jead — all  prove  to  us,  as  Mr.  Darcet  obferves  in  the  Journal 
de  Phyfique  for  1 783>  that  in  proportion  as  the  calcareous  Itone 
is  deprived  of  the  aeriform  principle,  it  combines  with  the  ig- 
neous ppnciple,  which  cannot  be  difplaced  but  by  the  way  of 
affinities.  The  beautiful  experiments  of  Meyer,  when  divefled 
pf  all  theory  prove  the  fame  thing. 

It  is  proved,  from  the  experiments  of  Dr.  Higgins,  that  the 
belt  lime  is  that  which  is  made  with  the  hardeit  and  mod  com- 
pact ftone  broken  into  fmall  pieces,  and  heated  flowly,  until  the 
furnace  is  become  of  a  white  heat.  This  heat  mufl  be  kept  up 
until  the  flone  is  no  longer  capable  of  effervefcing  with  acids. 
The  lime  becomes  over- burned  if  the  ignition  be  carried  to  a 
greater  degree  ;  and  the  produce  is  then  a  frit,  which  is  no 
longer  capable  of  being  divided  in  water,  or  of  refuming  with 
avidity  the  principles  it  had  loll. 

When  pieces  of  calcareous  ftone  of  different  fizes  are  cal-. 
cined,  the  lime  will  not  all  be  of  equal  goodnefs  5  the  fmall  pieces 
confiiting  of  over-burned  lime,  while  the  larger  pieces  are  fcarce- 
ly  altered  in  their  central  parts. 

The  belt  lime  is  that  which  is  the  moft  quickly  divided  by 
immerfion  in  water,  and  affords  the  greateft  quantity  of  heat  in 
this  procefs,  which  caufes  it  to  fall  into  the  fineft  powder. 
Good  lime  fliould  likewife  diffolve  in  the  acetous  acid  without 
pfFervefcence,   and  leave  the  Icaft  pofTible  quantity  of  refidue.  i 

Lime  continually  endeavours  to  refume  the  acid  and  the  w^- 
ter  of  which  the  ftone  w^  deprived  by  calcination  :  confequent- 
iy,  when  it  is  left  expofed  to  the  air,  it  cracks,  becomes  heat- 
ed, falls  into  powder  with  an  increafe  of  bulk,  and  refumes  the 
property  of  effervefcing.  It  is  therefore  of  importance  to  ufe  lime 
newly  made,  if  the  artift  be  defirous  of  poffeffmg  its  whole  force. 

Lime  is  fparingly  foluble  in  water,  and  this  folution  is  called 
lime-water  ;  the  lime  may  be  precipitated  by  ineans  of  carbon- 
ick  acid,  which  regenerates  calcareous  ftone  in  the  form  of  a 
precipitate. 

Lime-water  is  ufed  to  indicate  the  prefence,  and  determine 
the  proportion,  of  carbonick  acid  in   any  mineral  water. 

Phyficians  prefcribe  it  as  an  abforbent  and  detergent. 

When  lime-water  is  left  in  contact  with  the  air  of  the  atmof- 
phere,  a  pellicle  is  formed  at  its  furface,  known  by  the  name  of 
the  cream  of  lime  ;  this   is  the  regenerated  calcareous  flone. 

The  fuperb  bafon  of  Lampi,  one  of  the  two  principal  rcfer- 
Vpirs  which  fumifli  the  Royal  Canal  of  Langucdoc  with    water. 


i'9^  Mortar  of  the  Ancients* 

was  found  to  leak  at  the  jun(£lion  of  the  ftones.  The  H^IIfui 
engineer  who  diredls  thefe  works,  Mr.  Pin,  caufed  lime  to  be 
Hacked ;  which,  pafling  through  thefe  fmail  apertures,  became 
fupplied  with  carbonick  acid,  and  formed  a  cruft,  or  very  white 
covering,  over  its  whole  furface  :  fo  that  all  the  ftones  of  this 
fine  piece  of  mafonry  are  connected  together  by  this  cement  j 
and  at  prefent  conftitute  one  fingle  undivided  fubftance,  impen- 
etrable to  water. 

The  regeneration  of  calcareous  ftone  is  very  flowly  effecfled 
by  the  proceiles  hitherto  defcribed.  But  this  may  be  expedited 
by  prefenting  to  the  lime  the  principles  with  which  it  fo  llrong- 
ly  tends  to  combine  ;  this  is  accordingly  done  in  works  in  thq 
Jarge  way. 

Lime  is  ufually  ilacked  by  pouring  abundance  of  water  upon 
it.  A  violent  heat  is  thus  excited  ;  the  lime  falls  down  into 
powder,  and  a  pafte  is  afFor.ded  by  ftrongly  working  the  lime  to- 
gether in  proportion  as  it  becomes  faturated. 

The  count  Razoumouiki  has  taken  advantage  of  the  heat 
which  is  difcngaged  when  lime  is  flacked,  to  combine  the  lime 
with  fulphur. 

The  degree  of  heat  proper  to  effecl  this  combination  is  70  of 
Reaumur.  At  this  point  the  fulphur,  which  is  placed  in  contact 
■with  the  lime,  liquefies,  becomes  of  a  red  colour,  and  forms  a 
true  fuiphure  or  hepar  of  lime. 

Mortar  is  made  fimply  by  working  fand,  or  other  bodies  info-* 
luble  in  water,   together  with  flacked  lime. 

We  are  acquainted  with  two  kinds  of  fand  at  Montpellier  ; 
pith  fand,  and  river  fand  :  the  former  is  almofl  alv/ays  alterecf 
by  a  mixture  of  vegetable  and  calcareous  earth,  which  weakea 
its  efficacy ;  the  fecond  is  purer,  and  better  fuited  for  the  pur- 
pofe.  Inilcad  of  fand,  the  fragments  or  duft  of  ftone  may  be 
ufed  ;  the  angles  which  thefe  fragments  prefent,  and  the  rough- 
nefs  of  their  furface,  contribute  to  give  a  confiftence  to  the  mor- 
tar. 

The  hardening  of  mortars  appears  to  be  owing  merely  to  the 
progreiTive  regeneration  of  iime-ftone.  They  do  not  obtain  the 
greateft  degree  of  hardnefs  of  which  they  are  fufceptible,  until 
they  have  refumpd  all  the  carbonick  acid  of  which  the  ftone  was 
deprived  :  and  this  operation  is  very  flow,  unlefs  the  combuftion 
be  facilitated  bv  well  known  methods,  which  confiit  in  mixing 
fubftances  with  the  mortar  which  contain  either  the  carbonick 
acid,  or  a  principle  analagous  to  it,  fuch  as  vinegar. 

It  is  this  regeneration  of  Iime-ftone,  which  is  effected  by  the 
lapfe  of  time,  that  explains  to  us  why  the  hardeft  ftones  afford 
the  beft  lime  \  and  why  old  mortars  are  found  to  pofTefs  a  degree 
of  hardnefs  which  modern  artills  have  no  hopes  of  attaining. 


Plajler  Stone*  I  pi 

The  remains  of  ancient  buildings  have  induced  certain  philof- 
ophers  to  conclude,  that  the  ancients  were  in  pofTefTion  of  very 
valuable  procefles  for  the  making  of  mortar.  Mr.  De  la  Faye 
was  of  opinion,  that  thofe  enormous  malTes,  in  which  the  per- 
fection of  the  mechanical  procefles  of  the  ancients  only  was  ad- 
mired, were  made  by  coflcr  work  ;  and  he  imagined  that  he  had 
difcovered  in  Vitruvius,  Pliny,  and  St.  Auguilin,  that  their  pro- 
cefs  to  extlnguifli  lime  differed  from  ours  ;  and  that  the  great 
difference  which  appears  to  exift  betweert  the  ancient  and  mod- 
ern mortars  depends  more  particularly  upon  this  circumfl:ance. 
Thefe  interefting  refearches  have  induced  him  to  propofe  that 
the  lime  (hould  be  put  into  a  bafket  and  fufl«red  to  ilack  in  the 
air  i  as  he  thinks  by  this  means  it  would  preferve  a  greater  de- 
gree of  force,  and  be  lefs  weakened  than  by  the  ufual  procefles, 

Lorlot  has  attributed  the  fuperiorlty  of  the  mortars  of  the 
ancients  to  the  means  which  they  ufed  to  dry  them  fpeedily  ; 
ami  in  confequence  of  thei^  principles  he  mixes  pounded  bricks 
with  flints,  works  the  whole  together  with  flacked  lime,  and 
dries  the  mafs  with  one  fourth  part  of  quick-lime.  Care  mud 
be  taken  to  ufe  only  Hme  which  is  finely  pulverized  and  fifted  ; 
for  otherwife  the  mortar  would  crack,  and  be  very  imperfe6l. 

Nature  fometimes  prefents  to  us  a  fuitable  mixture  of  lime- 
ftone  and  fand,  to  form  an  excellent  mortar  without  any  mix- 
ture of  extraneous  fubfl:ances.  Mr.  De  Morveau  found  this 
Jime-ftbne  in  Burgundy  ;  Mr.  De  Puymaurin  has  defcribed  a 
fpecies  which  he  found  in  Berne  \  and  I  have  obferved  in  Cev- 
ennes  a  natural  mixture  of  this  kind,  in  which  the  proportion  of 
materials  was  fo  well  aflibrted,  that  nothing  more  was  neceflary 
than  to  calcine  it,  and  extinguifli  it  in  water,  to  form;  an  excellent 
iTiortar. 

•  SPECIES       II. 

Sulphate  of  Limci  Gypfum,  Selenite,  Plafl:er  Stone. 

The  Plafl:er  Stone  lofes  its  tranfparency  by  calcination,  at 
the  fame  time  that  it  becomes  pulverulent,  and  acquires  the  pro- 
perty of  again  feizing  the  water  of  which  it  had  been  deprived, 
and  refuming  its  hardnefs  j  it  does  not  give  fire  with  the  Iteel, 
nor  efl^ervefce  with  acids. 

We  are  more  particularly  indebted  to  Margrafl*  for  our  ac- 
quaintance with  the  confl:ituent  principles  of  plaiter  ;  and  from 
fubfequent  experiments  the  following  proportion  of  the  fame 
principles  has  been  afligned.  One  hundred  parts  of  gypfum 
contain  thirty  fulphurick  acid,  thirty-two  pure  earth,  thirty- 
eight  water  ;  it  lofes  nearly  20  per  cent,  by  calcination. 


t^a  Natural  Hi/!ory  of  Plajei". 

We  begin  to  be  equally  acquainted  with  the  formatioii  ot 
this  Hone,  The  chevaHer  De  Lamanon  has  alTerted,  that  ths 
numerous  quarries  of  plafter  which  are  found  in  the  vicinity  of 
Paris,  are  the  depofition  of  an  ancient  fluviatile  lake,  formed  by 
the  Seine,  Loifc,  and  Marne,  which  flowed  off  on  the  fide  of 
Meulan.  The  wrought  iron,  and  the  various  remains  of  animals 
•which  are  found  at  the  bottom  of  the  quarry  of  Mont  Matre, 
ihew  that  its  formation  is  not  very  ancient ;  and  the  indefatiga- 
ble naturalift  here  cited  confiders  the  felenite  as  originally  dif- 
perfed  in  the  water,  precipitated  in  confequence  of  its  fparing 
folubility,  and  heaped  together  in  places  determined  by  currents, 
waves,  and  other  circumftances. 

Thefe  facfls,  highly  interefting  as  they  are  in  the  natural  hif* 
tory  of  platter,  are  infufficient  for  the  chemift,  who  is  defirous 
of  knowing  likewife  in  what  manner,  and  under  what  circum- 
itances,  the  combination  of  the  fulphurick  acid  and  lime  is  made 
I  (hall  proceed  to  communicate  fome  obfervations  which  our 
province  affords. 

1.  I  have  obferved  in  a  black  and  pyritaceous  clay  of  Saint 
Sauveur,  extracted  out  of  the  work  called  Percement  Dillon, 
many  fmall  needle-formed  cryftals  of  felenite,  from  four  to 
eight  lines  in  length.  At  the  furface  of  the  foil  where  the  fame 
clay  is  more  decompofed,  cryflals  of  the  fame  nature,  but  lon- 
ger, thicker,  and  more  numerous,  are  alfo  found. 

2.  The  marly  and  pyritous  clay  of  Caunelle,  near  Moflbn, 
abounds  with  beautiful  cryftals  of  rofe-coloured  plafter,  in  the 
form  of  cocks-combs,  obferved  by  Mr.  Dorthes. 

-: .  The  plafter  quarry  of  La  Salle  exhibits  almoft  alternately 
flrata  of  plafter  and  ftrata  of  black  and  pyritous  clay,  which 
efHorefces  in  the  air. 

4.  Near  the  bridge  of  Herepian,  on  the  declivity  of  Cafcaf- 
tel,  at  Gabian,  and  in  many  other  places,  I  have  conftantly  found 
cryftals  of  gypfum  mixed  and  confounded  with  pyritaceous  clays. 

ij.  The  fulphureous  depofitions  of  folfatara  often  contain 
cryftals  of  felenite. 

From  thefe  faifts  It  appears  to  me  that  the  formation  of  gyp- 
fum may  ealily  be  conceived.  It  is  not  formed  excepting  in 
places  where  pyrites  and  clay  more  or  lefs  calcareous  are  found 
together  :  that  is  to  fay,  its  formation  appears  to  be  dependent 
on,  and  connected  with,  the  prefencc  of  fulphur  and  lime. 

Whenever,  therefore,  the  pyrites  is  decompofed,  the  fulphur-* 
ick  acid  which  thence  arifes  feizes  the  lime,  and  efilorefces  in 
fmall  cryftals,  which  are  carried  ofF  by  the  water,  and  fooner 
or  later  depoilted.  I  have  obferved  perceptible  depofitions  o£ 
plafter  on  the  banks  of  rivulets  which  wafh  pyritous  clays.      I 


Formation  and  Habitudes   of  Gypfum:  i^-^ 

iij^ve  likewife  feen  depofitions  of  the  fame  nature  in  rivers  whofe 
waters  have  been  llrongly  concentrated  by  the  burning  heat  of 
Qur  fummer.  And  confequently,  if  we  fuppofe  felenite  to  be 
uifperfed  in  more  confiderable  mafles  of  water,  there  will  be  no 
difficulty  in  conceiving  the  formation  of  thofe  ftrata  which  the 
plafter  quarries  exhibit. 

Meilrs.  De  Cazozy  and  Macquart  have  obferved  the  trafitiou 
of  the  gypfum  ofTTracovia  to  the  Hate  of  calcedony.  When  the 
nucleus  of  calcedony  is  determined  it  increafes  perceptibly  in 
the  courfe  of  time,  even  in  cabinets  -,  which  proves  that  the 
quartzofe  juice,  when  once  infiltrated  into  plafter,  combines 
with  the  lime,   and  determines  this  transformation. 

Mr.  Dorthes  has  proved  that  the  quartz,  in  cocks-combs  at 
]Dafly,  owed  its  origin  to  plalter  •,  that  this  laft  fubftance  having 
been  carried  away  by  folution,  the  quartzofe  juice  has  taken  its 
place.     Natural  hiflory  exhibits  feveral  of  thcfe  metamorphofes. 

Gypfum  is  found  in  the  earth  in  four  different  ftates. 

1.  In  the  pulverulent  and  friable  form,  which  conflitutes 
gypfeous  earth,  foiTd  flour,  &c. 

2.  In  folld  mailes,  which  conltltute  plafter-ftone. 

3.  In  ftalaflites,  or  fecondary  depofitions.  In  this  place  we 
rliay  arrange  the  ftriate'd  Tilky  gypfums,  the  cauliflowers,  the  gyp- 
feous alaballers,  and  that  prodigious  variety  of  forms  which  the 
ftaladites  afiumes,  whatever  may  be  its  component  parts. 

4.  In  determinate  cryitals  which  ufually  exhibit  the  following 
forms. . 

1.  The  comprefied  tetrahedral  rhomboldal  prifm. 

2.  The  hexahedral  prifm  truncated  at  its  fummit. 

3.  The  decahedral  rhomboid.  I  apprehend  that  the  lenticu- 
hir  gypfum  may  be  referred  to  this  lalt  form,  as  it  appears  to 
me  to  be  compofed  of  feveral  rhomboids  united  together  fide- 
ways.  At  all  events  I  have,  as  the  laft  refult,  obtained  the 
rhomboldal  form,  by  decompofing  this  variety. 

,  The  colour  of  gypfum  is  fubjecl  to  a  great  number  of  varie- 
ties, which  are  the  figns  of  various  qualities  relative  to  its  ufes. 
The  white  is  the  moll  beautiful,  but  fometlmes  it  is  grey  ;  and 
in  this  cafe  is  lefs  efteemed,  and  lefs  valuable. 

The  feveral  ftates  of  the  oxides  of  iron,  with  whicii  it  abounds 
in  greater  or  lefs  quantities,  conftitute  its  rofe-coloured,  red, 
black,  &:c^  varieties. 

The  fpecifick  gravity  of  gypfum  varies  according  to  its  purity. 
See  Meflirs.  Briflbn  and  Kirv/an  :  the  latter  found  it  fometlmes  of 
the  weight  of  2.32,  and  fometimes  1.87. 

It  is  foluble  in  about  five  hundred  times  its  weight  of  water, 
at  the  temperature  of  60  degrees  of  F*hrcnheit. 
2.. .A 


194'  Fluate  of  Lime  or  fluor*  Bpar. 

When  it  is  expofed  to  heat,  its  water  of  cryftallizatlon  is  diffi-^' 
pated,  it  becomes  opake,  lofes  its  confiftence,  arid  falls  into  pow- 
der. If  it  be  moiftened,  it  becomes  hard  again,  but  does  not 
refume  its  tranfparency ;  a  circumfiiance  which  appears  to  prove 
that  its  firft  ftate  is  a  ftate  of  cryftallization. 

If  it  be  kept  in  a  fire  of  confiderable  intenfity,  in  contact  with 
powder  of  charcoal,  the  acid  is  decompofed,  <§nd  the  refidue  is 
lime. 

Its  principles  may  likewife  be  feparated  by  finely  pulverizing 
it,  and  boiling  it  with  alkali. 

It  is  fufible  by  the  blow-pipe'according  to  Bergmann  ;  and  in' 
a  porcelain  furnace,  according  to  Darcet. 

The  management  of  the  fire  in  the  calcination  of  gypfum  is 
df  great  confequence.  Too  mi^ch  heat  decompofes  it  5  and  too' 
little  does  not  enable  it  to  unite,  and  form  a  hard  fubftance  with 
water. 

Calcined  gypriim  divides  and  difperfes  itfelf  in  water,  with 
which  it  forms  a  paftfe  that  may  be  caft  into  every  figure  imag- 
inable.  We  are  indebted  to  this  property  for  beautiful  orna- 
ments  in  the  infide  of  our  houfes  ;  but  it  cannot  be  ufed  for 
external  decorations  becaufe,  its  folubility  in  water  renders  it 
gradually  de{lni(ftib!e  by  that  liquid. 

SPECIES    llli 

Filiate  of  Lime,  Vitreous  Spar,  Fufible  or  Phofphorick  Spar,  Fluor  Spar. 

This  flone  is  a  combination  of  a  peculiar  add,  called  the  fluor 
acid,   with  lime. 

It  decrepitates  ort  heated  coals,  fike  muriate  of  foda,  or  com- 
mon fait.  When  flightly  heated,  it  fiiines  with  a  beautiful  blue 
colour,  that  remains  even  under  water,  or  in' acids.  The  refi* 
due  of  this  appearance  of  combuftion  is  white  and  opake, 

Itsfpecifick  gravity  is,  in  general,  from  3.14  to  3.18,  accord- 
ing to  Kirwan. 

This  fpar  enters  into  fufion  by  a  ftrong  heat,  and  corrodes  the 
the  crucible :  it  likewife  fufes  without  effervefcence  with  the 
mineral  alkali,  the  borate  of  foda,  and  the  phofphates  of   urine. 

This  ftone  pofleiTes  the  molt  lively  and  various  colours  ;  and 
it  is  known  under  the  names  of  falfe  emerald,  falfe  amethyft,  or 
falfe  topaz,  accordingly  as  its  colour  is  green,  violet,  or  yellow. 

The  blue  fluor  fpars  commonly  owe  their  colour  to  iron,  but 
fometimes  to  cobalt.  Berlin  Berchaft,  torn.  ii.  p.  330. — Green 
fluors  are  coloured  by  iron,  according  to  Rinmann.  The  moil; 
ufual  form  of  fluate  of  lime  is  the  cubick,  with  all  the-  modifica-" 
tibns  which  accompany  their  primitive  form. 


Properties  and  Hahittfdes  of  the  Acid  Fluor,  195 

•When  this  ftone  is  diftilled  with  its  own  weight  of  fulphurick 
,acid,  the  firft  produQ  confiltsof  eUftick  whitiih  vapours,  which 
.fill  the  receiver,  and  depofite  a  cruft  at  the  furface  of  the  v/ater, 
•while  the  water  itfelf  becomes  acidulous.  The  refidae  in  the 
retort  is  fulphate  of  lime,  according  to  Scheele.  The  cruft 
which  is  formed  on  the  water  of  the  receiver  is  fjliceous  earth  ; 
and  the  water  itfelf  being  faturated  with  the. vapour,  conftitutes 
the  fluorick  acid. 

The  moft  aftoni{hing  property  of  this  acid  is  doubtlefs  that  of 
feizing  the  filiceous  earth,  which  is  a  conftituent  principle  of 
the  glafs,  and  volatilizing  it  y/ith  itfelf. 

In  order  to  have  the  acid  in  a  flate  of  greater  purity,  and  ex- 
empt from  every  mixture  of  filex,  the  operations  are  performed 
in  retorts  of  lead  ;  but  Mr.  De  Puymaurin  is.convinced,  as  well 
as  myfelf,  that  the  acid  even  then  is  feldoni  pure,  becaufe  the 
moft  beautiful  fluor  contains  almoft  always  a  fmall  quantity  of 
/ilex,  which  the  acid  carries  with  it.  The  whiteft,  the  mofi 
tranfparent,  and  the  moft  regularly-cryftallized  fluor,  diftilled  on 
.the  water  bath  in  a  leaden  retort,  afforded  nee  an  acid  contami- 
nated by  a  fmall  quantity  of  filex. 

Mr.  Meyer  having  ufed  every  poflible  means  to  obtain  this 
acid  in  a  ftate  of  great  puril;^^,  is  convinced  that  when  the  acid 
does  not  find  Alexin  the  retort,  it  attacks  the  fides  of  the  re- 
ceiver, and  becomes  changed. 

This  acid  may  be  preferved  in  bottles  whofe  internal  furfa- 
.  ces  are  coated  with  wax  diffolved  in  oil. 

The  fluorick  acid  has  fome  analogy  with  the  muriatick ;  and 
ibme  chemifts  have  even  confounded  them  together  :  but  they 
differ  cffentialiy  from  each  other. 

The  fluorick  acid — 1.  When  combined  with  pot-afh,  prefents 
a  gelatinous  fubftance,  which  when  dry  retains  one  fifth  of  the 
alkali  employed,  and  forms  a  true  neutral  fait.  2.  It  acSls  near- 
ly in  the  fame  manner  with  foda.  3.  With  ammoniack  it  af- 
fords a  jelly,  which  when  dry  c^chibits  all  the  appearances  of 
filex.  4.  When  mixed  with  lime-water,  it  regenerates  the  flu- 
ate  of  hme.  5.  It  does  not  attack  gold,  nor  diffolve  filver  ;  and 
combines  in  preference  with  oxides,  fuch  as  thofe  of  lead,  iron, 
copper,  tin,  cobalt,  and  even  of  filver. 

One  part  of  the  fluate  of  lime,  fufed  with  four  parts  of  cauf- 
tick  fixed  alkali,  forms  a  fait  infoluble  in  water.  The  fame 
quantity  of  fluate  of  lime,  treated  in  the  fame  manner  with  the 
carbonate  of  pot-aftj  or  mild  vegetable  alkali,  affords  a  foluble 
fait  ;  and  at  the  bottom  of  the  water  a  calcareous  earth  is  found, 
which  proves  that  the  fluorick  acid  is  not  feparated  but  by  doubls- 
affinity. 


J ^6  Nitrate  of  Lime. 

This  ftone  which  hitherto  has  not  been  employed  but  as  a 
flux,  or  in  the  fabrication  of  ornaments,  appears  to  me  to  deferve 
the  moft  particular  attention.  Its  texture  feems  to  be  lamcllat- 
ed  like  the  diamond  ;  and  like  that  ftone  it  is  capable  of  double 
refradlon,  as  the  abbe  Rochon  has  obferved.  Its  phofphoref- 
cence  has  likewife  fome  relation  with  the  combullibility  of  tKe 
<liamond,  and  it  has  lively  and  varied  colours.  All  tliefe  cit- 
cumftances  eftablilh  an  analogy  between  thefe  two  fubftances' ; 
and  might  lead  us  to  fufpecl:  that  the  conftituent  principles  of 
the  diamond  exift  in  this  ftone,  mixed  and  combined  with  aa 
acid  and  lime,  &c. 

The  fluorick  acid  poflefTes  the  very  fingular  property  of  attack- 
ing glafs,  and  diilblving  and  carrying  off  its  filiceous  part. 
Margraff  firft  obferved  this  property  ;  but  Meftrs.  De  Puymau- 
jin  and  Klaproth  have  very  happily  applied  it  to  the  art  of  en- 
graving on  glafs. 

This  acid  is  employed  to  corrode  the  glafs,  in  the  fame  man- 
3ier  as  aqua  fortis  is  ufed  to  engrave  upon  copper. 

Some  authors,  particularly  Mr.  Mqnnet,  have  endeavoured 
to  prove  that  this  acid  was  nothing  elfe  but  a  niodification  of 
the  acid  ufed  in  the  decompofitiori  of  the  fpar.  They  fecm  to 
found  their  opinion  chiefly  on  the  circumftance,  that  the  acid 
obtained  exceeds  in  weight  the  fpar  made  ufe  of  ;  but  they 
have  negle£led  the  increafe  of  weight  which  muft  arife  from  the 
erofion,  diflblution,  and  mixture  of  the  glafs  of  the  diftilling  vef- 
fels.  And  indeed  thefc  experiments  do  not  appear  to  me  to  in- 
validate in  the  leaft  the  eternal  truths  which  have  iffued  from 
the  laboratory  of  the  celebrated  Scheele  ;  otherwife  fuch  modi- 
iications  in  the  acids  employed,  would  in  my  opinion  afford  a 
j)henomenon  ftill  more  aftonifhing  than  the  exiftence  of  this  pe-^ 
culiar  acid.  .    .       ^        ^. 

SPECIES       IV. 

Nitrate  of  Lime,  Calcareous  Nitie. 

This  fait,  as  well  as  thofe  which  remain  to  be  treated  of  in 
the  prefent  genus,  exifts  only  in  v/aters.  Their  great  folubili- 
ty,  and  their  fpontaneous  deliquefcence,  do  not  permit  them  to 
form  durable  mafics,  or  to  exift  in  the  form  of  ftones. 

The  nitrate  of  lime  is  principally  formed  hear  inhabited  pla- 
ces ;  old  plafter  affords  it  in  abundance  by  lixiviation.  It  is  one 
of  the  fahs  which  abound  in  the  mother  waters  of  the  falt-petre 
makers ;  and  it  has  been  found  in  fome  mineral  waters. 

It  is  ufually  obtained  in  the  form  of  fmall  needles,  applied 
Tideways  to  each  other, 


Calcareous  Marine  Salt.  ip^ 

When  a  folution  of  nitrate  of  lime  is  concentrated  to  a 
gelatinous  confiilence  nearly  equal  to  that  of  fyrup,  it  forms  iu 
procefs  of  time,  cry^als  in  hexahedral  prifms.  Two  part3  of 
cold  water  diflblve  one  of  this  fait ;  and  boiling  water  diflblves 
more  than  its  own  weight. 

Its  talte  is  bitter  and  difagreeable. 

It  liquefies  eauly  on  the  fire,  and  becomes  folid  by  cooling  ; 
if  it  be  (Irongly  calcined,  and  carried  into  the  dark,  it  is  lumin- 
ous, and  conllitutes  Baldwin's  phofphorus. 

It  lofes  its  acid  in  a  violent  and  continued  heat.  When  dis- 
tilled in  clofe  veflels,  it  affords  the  fame  products  as  nitre  by 
the  decompcfition  of  its  acid. 

Projected  upon  ignited  coals,  it  detonates  in  proportion  as  it 
becomes  drv. — Sec  De  Fourcroy, 

Its  acid  may  be  difengaged  by  means  of  clay  and  of  the  ful- 
phurick  acid. 

The  alkalis  and  baryies  precipitate  its  earth. 

The  fulphurick  falts,  and  the  carbonates  of  alkali,  decompofe 
it  by  double  affinity. 

SPECIES  v^ 

Muriate  of  Lime,  Calcareous  Marine  Salt. 

This  combination  exifts  more  efpecially  in  the  waters  of  the 
fea  J  and  contributes  to  give  to  thefe  waters  that  bitter  tafte 
which  has  improperly  been  referred  to  bitumens  that  have  no 
cxiftence. 

This  fait  is  very  deliquefcent  ;  one  part  and  a  half  of  water 
diiTolves  one  of  this  fait ;  and  hoc  water  diflblves  more  than  its 
own  weight. 

'  It  may  be  made  to  cryftallize  by  concentrating  its  folution  to 
the  45th  degree  of  Baume,  and  expofing  it  afterwards  in  a  cool 
place. 

With  thefe  precaution^  it  affords  a  fait  in  tetrahedral  prifms 
terminated  by  four-fided  pyramids. — See  de   Fourcroy. 

It  enters  into  fufion  with  a  moderate  heat  *,  but  is  decompofed 
with  great  difficulty.  It  acquires  by  calcination  the  property  of 
fhining  in  the  dark,  and  is  called  the   phofphorus  of  Romberg. 

It  is  decompofed  by  barytes  and  the  alkalis.  The  concentra- 
ted fulphurick  acid,  poured  upon  a  very  Itrong  folution  of  mu- 
riate of  lime,  difengagcs  the  acid  in  vapours,  and  fcrms  a  folid 
precipitate  :  an  appearance  which  feems  in  an  iniiant  to  tranf- 
form  two  liquids  into  a  folid,  and  produces  a  very  (triking  ef- 
fect. The  theory  of  this  phenomenon  is  eafily  deduced  from 
the  very  great  folubility  of  the  muriate,  and  the  almoft  abfolute 
Jnfolubility  of  the  fulphate  which  takes  its  place. 


;2^8  <!la!careous  Phofphoric'k  Salt. 

SPECIES       VI. 

Phofphate  of  Lime,  Calcareous  Phofpliorick  Salt. 

This  phofphate  of  lime  has  been  found  in  Spain,  in  the  king- 
,dlom  of  Eitramadura.  by  Mr.  Bowie. 

It  is  a  whitifh  flone  of  confiderable  denfity,  not  hard  enouglj 
.4:0  give  fire  with  the  fteel.  It  is  found  in  horizontal  ftrata,  re- 
pofing  upon  quartz,  and  exhibiting  vertical,  flattened,  and  clofe 
.fibres.  When  thrown  on  ignited  coals  it  does  not  depcrepitate^ 
but  burns  quietly,  and  affords  a  beautiful  green  light,  which  feems 
to  penetrate  through  it,  and  does  not  difappear  fo  quickly  but 
that  a  fufEcient  time  is  admitted  to  contemplate  its  brilliancy 
with  admiration.  Before  the  biow-pipe  it  runs  ir^to  a  white 
;€namel,  without  boiling  up  ;  whereas  bones  fupport  the  mofi: 
violent  heat  without  fulion.  Its  habitudes  with  the  nitrick  and 
fujphurick  acids  are  the  fame  as  thofe  of  calcined  bones  :  its 
acid  may  be  feparated  and  brought  into  the  ftate  of  an  animal 
glafs  •,  it  may  be  decompofed,  and  the  phofphorus  extracted. 

Mr.  Prouft,  from  whom  we  borrow  thefe  intereftirig  details, 
pbferves  likewife  that  this  ftone  is  found  to  compofe  the  mafs  of 
entire  hills  in  the  neighbourhood  of  the  village  of  Logrofan,  in 
the  jurifdidtion  of  Truxillo,  a  province  of  Eitramadura.  The 
houfes  and  the  walls  of  inclofures  are  built  of  it. 

GENUS     n. 

Earthy  Salts  with  Bafe  of  Barytes. 

The  moft  common  ftate  in  which  Barytes  is  found  ia  in  com^ 
bination  with  the  fulphurick  acid. 

SPECIES      I. 

Sulphate  of  Barytes,  Ponderous  Spar. 

This  flone  is  the  moft  ponderous  we  are  acquainted  with» 
Its  fpecifick  gravity  is  commonly  from  4  to  4.6. 

It  decrepitates  in  the  fire,  melts  before  the  blow-pipe  without 
addition,  and  fluxes  diffolve  it  with  effervefcence. — See  the 
siotes  of  the  abbe  Mongez.* 

Mr.  Darcet  fucceeded  in  fufing  it  jn  a  porceHan  furnace. 

*  Manutl  du  Mineralcgifle. 


Ponderous  Spar.  {^ 

It  has  been  often  confounded  with  gyp fum  and  fluor  fpar  y 
^ut  the  chara6lers  of  thefe  two  fubftances  are  very  different. 

It  almoft  always  accompanies  metallick  ores,  and  it  is  even 
confidered  as  an  happy  prefage  of  finding  them.  Becher  has 
affirmed  that  it  was  a  certain  indication  vel  prefentis  vel  futiiri 
meialli  :  and  I  think  that  there  is  reafon  to  confider  it  as  the 
Vitrifiable  ftone  of  this  celebrated  naturaUft.  The  proofs  of  my 
aflertion  may  be  feen  in  the  preHminary  ideas  of  my  treatife  on" 
itietaUick  fubftances  (in  this  work.)  The  analogy  between  this' 
flone  and  metals  has  been  eftablilhed  by  th^  experiments  of 
Bergmann  and  of  Mr.  Lavoifier. 

This  ftone,  when  rather  {trongly  heated,  exhibits  a  bluifh 
light  in  the  dark.  Toform  thefe  kinds  of  phofphori,  the  fpar  is' 
pulverized,  the  powder  is  kneaded  up  with  mucilage  of  gurr>^ 
tragacanth,  and  the  pafte  is  formed  into  pieces  as  thin  as  the 
blade  of  a  knife.  Thefe  pieces  are  afterwards  dried,  and  flrong- 
ly  calcined  by  placing  them  in  the  midd  of  the  coals  of  a  fur- 
nace j  they  are  afterwards  cleared  by  blowing  on  them  with  the 
bellows.  In  this  ftate,  if  they  be  expofed  to  the  hght  for  a  few 
minutes,  and  afterwardis  carried"  into  a  dark  place,  they  fhinc 
like  glowing  coals.  Thefe  pieces  (liine  even  under  water  ;  but 
they  gradually  become  deprived  of  this  property,  which  how- 
ever may  be  reftored  again  by  a  fecond  heating. — See  De  Four- 
croy. 

Ponderous  fpar  is  eafily  divided  into  plates  by  the  flighted 
blow  ;  and  the  mod  ufual  form  which  it  afFeils  is  that  of  an 
hexahedral  prifm,  very  flat,  and  terminated  by  a  dihedral  fum- 
rnit. 

Ponderous  fpar  has  been  found  at  the  diftance  of  one  league 
from  Clermont  d'Auvergne,  in  the  form  of  hexahedral  prifms 
terminated  by  a  letrahedral  or  dihedral  pyramid.  I  have  (ttn 
Cryilals  of  two  inches  in  diameter. 

It  frequently  happens  that  the  form  of  thefe  cryflals  is*  not 
very  determinate  ;  but  all  the  flones  of  the  nature  of  thefe  ex- 
hibit a  confufed  alTemblage  of  fev^cral  plates  applied  one  upon 
another,  and  capable  of  being  feparatcd  by  a  very  flight  blow. 
Ponderous  fpar  is  infuluble  in  water  ;  and  upon  this  property 
is  founded  the  virtue  poflefTed  by  the  muriate  of  barytes,  to  man- 
ifeft  the  flightefl  portions  of  fulphurick  acid  in  any  combina- 
tion which  contains  it. 

Barytes  adheres  more  ftrongly  to  acids  than  the  alkalis  them- 
ielvcs  do  ;  and  when  the  carbonates  of  alkalis  precipitate  it,  the 
^S^O.  takes  place  in  the  way  of  double  afhnity. 


2oo  Carhnatii  Nitrate  and  Muriate  of  Baryte^. 


SPECIES       II, 

Carbonate  of  Barytes. 

This  combination  luis  thefpecifick  gra\^ity  of  3.773. 

One  hundred  parts  contain  twenty-eight  water,  feven  acid, 
fixty-five  pure  earth. 

The  fulphurick,  nitrick,  and  other  acids  attack  it  wlthefFer- 
vefccnce. 

Although  the  carbonick  acid  pofleflcs  \\\q  ftrongeft  affinity 
tiath  this  earth,  it  is  very  feldom  found  in  combination  with  it  : 
and  I  am  acquainted  with  its  exiftence  only  on  the  authority  of 
Mr.  Kirwan,  who  affirms  that.  Dr.  Withering  prefented  him 
with  a  fpecimen  from  Alilon  Moor,  in  Cumberland  ;  which  re- 
sembles alum,  with  the  difference  that  its  texture  is  ftriated,' 
and  its  fpecifick  gravity  is  4.33 1.* 

Mr-  Sage  analyfed  this  ftone,  which  was  prefented  to  him  by 
Mr.  GreviUe.     See  the  Journal  de  Phyfique  for  April  1788. 

SPECIES       III. 

Mtrateof  Barytes. 

The  nitrick  acid  difTolves  pure  barytes,  and  forms  a  fait 
which  cryftallizes  fometimes  in  large  hexagonal  cryftals,  and 
frequently  in  fmall  irregular  cryftals. 

The  nitrate  is  decompofed  by  fire    and,  affords  oxigene. 

The  pure  alkalis  do  not  difengage  the  barytes,  but  the  alka- 
line carbonates  precipitate  it  by  double  affinity. 

The  fulphurick  and  fluoTick  acids  feize  this  earth  from  the 
tiitrick  acid.  ^ 

It  has  not  yet  been  found  native^ 

SPECIES       IV. 

Muriate  of  Barytes. 

This  fait  is  capable  6f  afTuming  a  form"  confiderably  refem- 
bVmg  that  of  fpar  in  tables  or  plates.  It  exhibits,  with  the 
eirths,  acids,  and  alkali,  phenomena  nearly  fimilar  to  thofe  of 
tlie  nitrate  of  barytes. 

It  forms  one  of  the  mofl  interefting  re-agents  to  afcertain 
the  exigence  of  the  fmalleft  particle    of   fulphurick  fait   in  any 

*  ft  is  plentifully  found  in  England,  in  the  lead  mine  of  Anglezark^ 
rear  Chorlcy  ia  Lancalhire..     See  the  Manchefter    Memoirs,  vol.  iii.  J*. 


Epfom  Salt.  201 

Water  y  becaufe  by  the  fudden  exchange  of  principles,  the  ref^^lt 
is  ponderous  fpar,  which  immediately  falls  down. 
It  has  not  yet  been  found  in  a  native  ftare. 

GENUS      III. 
Earthy  Salts  with  Bads  of  Magnelia, 

Tiiefe  falts  were  not  well  known  before  the  time  in  which 
the  celebrated  Black  proved  that  they  ought  not  to  be  confound- 
ed with  calcareous  falts.  They  may  be  diftinguifhed  fram  thefe 
by  the  bitter  tafte  which  almofl  all  of  them  poflefs. 

They  are  in  general  very  foluble  in  water.  Lime-water  pre- 
cipitates them,  as  does  likewife  ammoniack,  or  the  volatile 
alkali. 

SPECIES       I. 

Sulphate  of  Magnefia,  Epfom  Salt. 

This  fait  is  frequently  met  with  ;  it  exifts  in  feveral  mineral 
waters,  fuch  as  thofe  of  Epfom,  of  Sedliz,  &c.  It  was  at  firll 
diftinguifhed  by  the  name  of  the  fprings  which  produced  it  ; 
and  it  is  (till  known  by  the  name  of  the  bitter  cathartick  fait,  on 
account  of  its  tafle  and  virtues. 

The  fulphate  of  magnefia,  in  commerce,  comes  either  from 
the  fait  fprings  of  Lorraine,  from  which  this  fait  is  extraded 
with  a  mixture  of  fulphur  ;  or  otherwife  from  the  fait  works  in 
the  environs  of  Narbonne,  where  it  is  extracted  from  the  moth- 
er waters  which  contain  it  abundantly. 

The  fulphate  of  magnefia,  in  commerce,  has  the  form  of  fmall 
filky  needles,  very  white.  It  does  not  efflorefce  in  the  air, 
which  diftingullhes  it  from  the  fulphate  of  foda. 

The  cryftals  of  the  pure  fulphate  of  magnefia  are  quadrangu* 
lar  prifms,  terminated  by  pyramids  of  an  equal  number  of  fides. 

The  fulphate  of  magnefia  prepared  in  our  fait  works  is  foI4 
at  from  thirty  to  forty  livres  the  quintal  ;  it  containsin  the 
pound  three  fixteenths  of  fulphate  of  foda,  two  fixteenths  mu- 
riate of  magnefia,  one  fixteenth  muriate  of  foda,  fix  fixteenths 
true  fulphate  of  magnefia  :  the  reft  confiUs  of  falts  with  bafis 
of  lime. 

The  fulphate  of  Magnefia,  when  expofed  to  the  fire,  liquefies, 
and  lofes  half  its  weight.  The  remainder  is  dry,  and  requires 
a  (trong  fire  to  fufe  it. 

Water  diflblves  its  own  weight  of  this  fait,  at  the  temperature 
of  60  degrees  of  Fahrenheit's  thermometer. 
2...B 


202'  Carbonate  of  Magnefia. 

One  hundred  parts  of  this  fait  contain  twenty-four  parts 
acid,  nineteen  earth,  and  fifty-feven  water. 

It  exifts  in  all  the  waters  in  the  environs  of  Montpellier. 

Sometimes  it  is  found  effloreicent  upon  fchiili,  from  which 
it  may  be  collected.  I  have  found  it  upon  a  mountain  in  Rou- 
ergue,  in  a  quantity  fufficiently  great  to  be  colle6i:ed  to  advan- 
tage :  birds  of  parfage  devour  it  greedily.  This  fait  is  ufed  in 
preference  to.  others  as  a  purgative. 

SPECIES      II. 
Nitrate  of  Magnefia. 

The  celebrated  Bergmann,  who  has  combined  magnefia  with 
the  various  acids,  obferves  that  the  nitrick  acid  forms  with  it  a 
ialt  capable  of  affording,  by  proper  evaporation,  prifmatick, 
quadrangular,  truncated  cryfhals.  The  fame  chemift  adds,  that 
this  fait  is  deliquefcent.  Mr.  Dijonval  affirms,  that  he  obtain- 
ed cryftals  that  were  not  deliquefcent  •,  and  accident  has  afford- 
ed me  a  fait  of  this  kind  in  mother  water  cf  nitre  concentrated 
to  the  45th  degree  of  the  areometer.  Its  form  was  that  of 
prifms  with  four  fides,  very  much  flattened,  very  thick,  and 
very  fhort. 

This  l^ilt  decompcfes  the  muriates ;  alkalis  precipitate  its 
magnefia,  as  does  likewife  lime. 

SPECIES     rir. 

Muriate  of  Magnefia, 

The  muriate  of  magnefia  exifts  in  the  mother  water  of  our 
fait  works  ;  its  tafte  is  very  bitter. 

According  to  Bergmann,  it  forms  a  fait  in  fmall  needles,  fo 
deliquefcent  that  it  cannot  be  obtained  but  by  ftrongly  concen- 
trating the  folution,  and  afterwards    exprofing  it  to  intenfe  cold. 

Lime-water,  barytes,  and  the  alkalis  precipitate  the  magnefia  5 
it  may  likewife  be  feparated  by  means  of  fire. 

SPECIES       IV. 

Carbonate  of  Magnefia. 

Though  magnefia  has  the  greateH:  affinity  with  the  carbon- 
ick  acid,  I  do  not  think  that  nature  has  ever  exhibited  thii  com- 
bination.    It  is  obtained  by   precipitating  the   magnefia  from 


Aluminous  Salts,  203 

{pfom  fait,  by  means  of  the  carbonates  of  alkali ;  and  in  this 
jate  it  is  called  efFcrvefcenc  magnefia,  or  magnefia,  not  cal- 
tined. 

The  carbonate  of  magnefia  contains  in  the  quintal  thirty  parrs 
acid,  forty-eight  earth,  and  twenty-two  water. — Sec  Kirwan 
and  Bergmann. 

Magnefia  flicks  to  the  tongue  ;  and  aflumes,  in  drying,  a 
certain  tranfparency,  which  it  preferves  until  it  has  loft  all  its 
water,  which  is  not  eafily  driven  off. 

Fire  carries  oit  the  water  and  the  acid  ;  and  in  this  ftate  the 
refidue  is  called  callcined  magnefia, 

The  carbonate  of  magnefia  is  foluble  in  water  in  the  propor- 
tion of  feveral  grains  in  an  ounce  of  the  fluid. 

But  we  are  indebted  to  Mr.  Butini  for  a  very  fingular  obfer- 
vation — that  cold  diflblves  more  than  hot  water,  and  that  the 
magnefia  may  be  precipitated  by  heating  the  water  which  holds 
it  in  folution.  Hence  it  arifes  that  waters  loaded  with  magne- 
fia become  white  and  turbid  by  ebullition. 

The  celebrated  Bergmann  had  advanced  that  the  carbonate  of 
magnefia  is  cryftallizable.  Mr.  Butini,  by  concentrating  a  fat- 
urated  folution  of  this  fait  with  a  gentle  heat,  obtained  groups 
of  cryftals,  which,  when  examined  by  the  microfcope,  appeared 
to  be  hexagonal  truncated  prifms.  I  have  obtained  fimilar 
fnow-like  flocks  by  precipitating  magnefia  by  the  addition  of  an 
alkali,  drop  by  drop. 

The  carbonate  of  magnefia  is  ufed  in  medicine  as  a  purgative. 
The  calcined  magnefia  ought  to  be  preferred  as  an  abforbent, 

GENUS      IV. 
Earthy  Salts  widi  Bafe  of  Alumina. 

The  fubftance  which  In  the  arts  is  known  by  the  name  of  Clay, 
is  a  natural  mixture  of  feveral  earths. 

Alumine,  or  pure  clay,  is  capable  of  combining  with  the 
greateft  part  of  the  known  acids  j  but  the  mod  common  of 
thefe  falts  is  alum. 

SPECIES      I, 

Sulphate  of  Alumine,  Alum, 

Though  alum  be  very  commonly  met  with,  yet  the  combi- 
nation of  principles  which  conftitute  it  is  notefi'eded  without 
oonfiderable  difiicultv. 


2C4  Manufacltire  of  Alum, 

Pure  clay  upon  which  the  fulphurick  acid  is  digefted,  is  dif- 
folved  with  difficulty  :  and  it  is  by  no  means  eafy  to  bring  this 
combination  to  regular  cryftals.  The  ufual  product  is  a  faltj 
which  appears  to  be  formed  by  fcales  applied  one  upon  the  other. 

The  nioft  ordinary  procefs  to  diffolve  alumine  by  means  of 
an  acid,  confifls  in  calcining  the  clay,  impregnating  it  with  the 
acid,  and  facilitating  its  atlion  by  an  heat  of  50  or  60  degrees 
of  Reaumur.  But  a  fimpler  method,  which  I  have  ufed  in  my 
manufaftory  of  ajum,  conn  (Is  in  prefenting  the  acid  in  vapours, 
and  under  the  dry  form,  to  the  clay  properly  prepared.  For 
this  purpofe  I  calcine  my  clays,  and  reduce  them  into  fmatl 
pieces,  which  I  fpread  over  the  floor  of  my  leaden  chambers. 
The  fulphurick  acid,  which  is  formed  by  the  combuftion  of  a 
mixture  of  fulphur  and  faltpetre,  expands  itfelf  in  the  cavities 
of  thefe  chambers  and  exifts  for  a  certain  time  in  the  vaporous 
form.  In  this  form  it  has  a  ftronger  a£tion  than  when  it  has 
been  weakened  by  the  mixture  of  a  quantity  of  water  more  or 
!lefs  confiderable  :  fo  that  it  feizes  the  earths,  combines  with 
them,  caufes  them  to  increafe  in  bulk  by  ihe  efflorefcence  which 
takes  p!ace,  and  at  the  end  of  feveral  days  the  whole  furfaceex- 
pofed  to  the  vapour  is  converted  into  alum.  Care  is  taken  to  ftir 
thefe  earths  from  time  to  time,  that  they  may  fucceflively  prefent 
uU  their  furfaces  to  the  adlion  of  the  acid. 

But  whatever  procefs  may  be  ufed  to  combine  the  acid  with 
clay,  it  is  neceflary  to  expofe  the  aluminized  earths  to  the  air 
during  a  greater  or  lefs  fpace  of  time,  in  order  that  the  combi- 
nation may  be  more  accurate,  and  the  fatui:ation  more  com- 
plete. 

Mod  of  the  alum  in  commerce  is  afforded  by  ores  which  are 
dugout  of  the  earth  for  this  purpofe.  We  may  reduce  all  the 
operations  of  this  manufacture  to  three  or  four  ;  the  decompofi- 
tion  of  the  ore,  the  lixiviatlon  of  the  ore,  the  evaporaiipn  of 
thefe  Kxiviums,  and  the  cryftaUization  of  the  alum. 

I.  The  decompofition  of  the  mineral  is  efFe^fled  either  \x\  the 
open  air  without  afFiftance;  or  elfe  by  means  of  fire. 

When  the  mineral  is  left  to  decompofe  fpontaneoufly,  nothing 
more  is  done  than  to  difpofe  the  (tone  which  contains  the  prin- 
ciples of  alum  in  ftrata  or  layers.  The  pyrites  becomes  heated  \ 
acid  is  formed,  which  diffolver.  the  clay  ;  and  the  fait  arifing 
from  this  combination  exhibits  itfelf  by  the  efHorefcence  of  the 
ore.  The  decompofition  may  be  accelerated  by  watering  the 
heap  of  pyrites  ;  but  the  operation  may  be  Hill  more  abridged 
by  the  afliftance  of  fire. — ^The  method  of  applying  the  heat  vari^^s 
prodigioufly.  On  this  head  Bergmann  may  be  confulted  ;  but  in 
eeneral  it  may  be  obfervcd  that  it  ought  not   to   be  either  tOQ 


I 


ManufaBure   of  Alum,  205 

ftrong  or  too  weak.     In  the  firft  dafe  it  volatilizes  the  fulphur, 
and  in  the  fecond  it  retards  the  operation. 

The  ore  of  alum  is  fometimes  impregnated  with  a  fufficient 
quantity  of  bitumen  to  maintain  the  combuftion. — See  my  Me- 
moir on  the  Alum  Ore  ofVabrais,  1785. 

2.  When  the  ore  has  efflorefced  into  akim,  the  fait  is  extracted 
})y  lixiviation.  For  this  purpofe  the  fame  water  is  pafled  over  fev- 
eral  heaps  of  aluminous  earth,  in  order  to  faturate  it-  The  wa- 
ter which  is  firft  pafled  over  the  earth  difiblves  in  preference  the 
vitriol,  whicji  is  more  or  lefs  abundant ;  and  this  fait  may  bo 
feparated  from  the  alum  by  a  previous  cold-walhing. 

3.  This  lixivium,  or  faline  folution,  is  carried  into  leaden  cal- 
drons, where  the  fluid  is  properly  concentrated.  In  this  pait 
of  the  procefs  it  is  that  an  accurate  faturation  of  the  alum  is  ef- 
fected when  the  acid  is  in  excefs  ;  and  for  this  purpofe  alkalis 
are  added,  which  ferve  likev/ife  fingularly  to  facilitate  the  cryf- 
taliization.  The  celebrated  Bergmann  has  propofed  to  boil  clay 
with  the  folution,  to  faturate  the  excefs  of  acid.  This  procefs 
feems  in  every  point  of  view  to  be  advantageous  ;  but  it  appears 
to  me  to  be  imprafticable,  becaufe  the  fuperabundant  acid  cannot 
be  made  to  combine  with  the  clay,  but  by  a  very  long  ebullition, 
and  I  have  obferved  that,  by  afterwards  evaporating  the  fluid  to 
caufe  it  to  cryftallize,  this  clay  falls  down  and  oppofes  the  cryf- 
tallization.  I  have  varied  the  procefs  in  a  variety  of  ways,  with- 
out obtaining  the  fuccefs  which  its  celebrated  author  predicted . 

There  arc  methods  of  greater  or  lefs  accuracy  to  judge  of  the 
degree  of  concentration  to  which  it  is  proper  to  carry  the  lixiv- 
iaim,  in  order  to  obtain  a  good  cryftallization  ;  fuch  are,  the  im- 
merfion  of  an  egg  in  the  liquid,  the  effufion  of  fome  drops  in 
the  lixivium  on  a  plate,  &c.  Mr.  De  Morveau  has  propofed  a 
metallick  hygrometer  5  but  this  inftrumcnt  cannot  be  confidered 
as  very  accurate,  becaufe  its  immerfion  in  the  liquid  is  propor- 
tional to  the  heat  of  the  fluid  in  which  it  is  plunged. 

4.  The  lixivium  is  then  conveyed  into  coolers,  where  it  cryf- 
tallizes  by  mere  refrigeration.  The  pyramids  of  alum  are  con- 
ftantly  turned  towards  the  bottom  of  the  vefici,  more  efpecially 
jthofe  which  fix  themfelves  to  the  fticks  which  are  put  into  the 
liquor  to  muhiply  the  furfaccs. 

Alum  affects  the  form  of  two  tetrahedral  pyramids,  applied 
to  each  other  bafc  to  bafe.  Sometimes  the  angles  are  trunca- 
ted, and  thefc  truncatures  take  place  moil  frequently  when  the 
lixivium  is  flightly  to  acid. 

This  fait  requires  fifteen  times  its  weight  of  water  to  dilToIve 
it,  at  the  temperature  offixty  degrees  of  Fahrenheit,  according 
to  Kirwan. 


2o6  Carbonate  of  Alumwe, 

Its  tafle  is  flyptick  ;  it  lofes  its  water  of  cryftallization  by 
heat  5  at  the  fame  time  that  it  fwells  up,  and  is  converted  into  a 
light  and  wliite  fubftance,  called  burned  or  calcined  alum. 

If  it  be  urged  by  a  violent  degree  of  heat,  it  lofes  part  of  its 
acid,  and  becomes  tailelefs.  The  refidue  is  no  longer  fufcepti- 
ble  of  cryftallization,  and  precipitates  in  the  form  of  a  very  fine 
adhefive  powder,  in  proportion  as  the  water  is  difperfed  by  evap- 
oration. 

Alumine  is  precipitated  from  this  folution  by  magnefia,  ba- 
rytes,  and  the  alkalis:  thefe  lait  diflblve  the  precipitate  in  proper^ 
lion  as  it  is  formed,  if  they  be  added  in  excefs. 

Alum  is  a  very  valuable  material  in  the  arts.  It  is  the  foul 
of  the  art  of  dying,  and  ferves  as  the  mordant  to  all  colours. 
It  is  ufed  to  prepare  leather,  to  impregnate  paper  and  cloths  in- 
tended to  be  printed.  It  is  added  to  tallow,  to  render  it  harder  ; 
it  enters  into  the  preparation  of  a  glue  for  the  deftruQion  of  ver- 
min j  it  is  employed  in  England,  and  elfe where,  to  give  white- 
nefs,  and  additional  weight  to  bread.  When  fufed  with  falt- 
petre  of  the  firft  boiling,  it  forms  a  very  white  cryflal  mineral. 

The  printers  rub  their  balls  with  calcined  alum  to  caufe  then\ 
to  take  the  ink.  Surgeons  employ  it  to  corrode  fungous  or 
proud  flelh. 


SPECIES       II. 
Carbonate  of  Alumine. 

The  argillaceous  earth  precipitated  from  the  folution  of  alufti 
by  the  carbonates  of  alkalis,  combines  with  their  acid  ;  but  this 
fait  is  very  rarely  found  in  nature.  I  know  only  of  the  obferva-? 
tion  of  Schreber  which  afcertains  its  exiftence.  This  naturalift 
afTerted  that  the  earth  known  by  the  name  of  Lac  Lunse  is  a  true 
carbonate  of  alumine. 

Although  alumine  be  foluble  in  the  other  acids,  we  are  very 
little  acquainted  with  its  combinations.  It  is  only  known  that 
the  nitrick  acid  diflblves  it,  that  the  folution  is  aitringent,  and 
that  it  may  be  obtained  in  fmall  flyptick  and  deliquefcent  cryf- 
tals. 

The  muriatick  acid  has  a  more  evident  a£lion  upon  alumine. 
This  muriate  is  gelatinous  and  deliquefcent. 

Thefe  falts  have  not  been  applied  to  any  ufe,  and  tlicy  are  no 
where  found  in  nature. 


Earthy   Mixtures,  207 

GENUS      V. 
Earthy  Salts  with  Bafe  of  Silex. 

Silex  is  of  all  the  known  earths  that  which  combines  the  mod 
clifiicultly  with  acids. 

We  are  even  acquainted  with  no  other  acid  than  the  fluoricfc 
which  exerts  an  evident  a£lion  upon  it.  It  rifes  with  it,  and 
holds  it  in  folution  until  it  abandons  it  to  unite  with  water. 

Some  experiments  of  Mr.  Achard  gave  reafon  to  think  that 
the  carbonick  acid  diffblved  (ilex  ;  but  the  Parifian  chemift  did 
not  obtain  the  refults  announced  by  the  chemift  of  Berlin.  M. 
De  Morveau  feems  to  have  proved  that  iron  and  the  carbonick 
acid  were  neceflary  to  form  rock  cryftals  ;  but  this  acid  does  not 
remain  united  and  combined  with  the  earth  ;  fo  that  we  h:ive 
not  hitherto  arrived  at  any  proof  of  its  diffblving^  virtue. 

CLASS        II. 

Concerning  the  Combination  and  Mixture  of  Primitive  Earths,  or  Earthy 

Mixtures. 

The  pure  and  fimple  earths,  fuch  as  we  have  defcribed  them, 
are  rarely  found  on  the  furfacc  of  the  globe.  They  are  con- 
llantly  mixed  wirh  each  otlier,  and  form  maiTes  of  greater  or 
lefs  magnitude,  and  various  hardnefs,  according  to  the  nature 
of  the  earths,  their  ftate  of  divifion,  and  the  character  of  the  for- 
eign fubftances  which  are  combined  with  them,  fuch  as  iron, 
bitumens,  &c. 

It  may  be  eafily  underftood  that  the  number  of  compofitions 
which  can  refult  from  the  mixture  of  five  primitive  earths, 
would  be  infinite,  if  we  were  to  pay  attention  to  fuch  flight  va- 
rieties as  depend  on  the  proportions  of  the  mixture  :  but  I  fliall 
not  confider  any  mixtures  as  conftituting  fpecies  truly  diftinCt, 
except  fuch  as  differ  in  the  identity  of  their  conltituent  princi- 
ples. The  flight  differences  in  the  proportions  of  thefe  princi- 
ples may  indeed  occafion  modifications  in  the  form,  the  hard- 
nefs, the  colour,  &c.  But  thefe  can  never  conftitute  more  than 
varieties. 

We  (hall  naturally  deduce  the  genus  from  the  ftone  or  earth 
which  predominates  in  aiiy  mixture,  and  appears  to  communi- 
cate its  own  character  to  the  total  mafs.  In  this  manner  we 
{hall  clafs  among  the  calcareous  mixtures  fuch  ftones  as  exhibit 
to  our  obfervation  the  properties  of  lime-ftone  to  fuch  a  degree, 
that  they  would  be  taken  to  be  purely  calcareous  if  the  chemical 
nnalyfis  did  not  prove  the  exiftence  of  other  principles. 


2o8  Calcareous    Mixtures. 

The  genus  ought  not  in  ftn<flnefs  to  be  taken  and  deduced 
from  the  earthy  principles  which  predominates  ;  for  the  charac- 
ter of  the  whole  mafs  or  of  the  mixture,  is  very  frequently  given 
by  an  earth  which  does  not  form  the  mod  abundant  principle  ; 
as  we  obferve  more  efpecialiy  in  magnefian  earths,  where  the  filex 
predominates  over  the  magnefia. 

GENUS      I, 

Calcareous  Mixtures, 

According  to  the  principles  we  have  laid  down,  we  muft  re- 
fer to  this  place  thofe  ftony  mixtures  in  which  the  properties  of 
iime-ftone  predominate. 

SPECIES      I. 
Lime-ftone  and  Magnefia* 

This  mixture  is  very  common  ;  almofl  all  the  calcareous 
ftones  contain  magnefia.  Mr.  Bayen  has  defcribed  a  variety  in 
the  Journal  de  Phyfique,  t.  xili.  which  contain  in  the  hundred 
parts  feventy-five  carbonate  of  lime,  twelve  magnefia,  and  thir- 
teen iron,  it  is  the  earth  of  Crsntzwald.  Mr.  Woulfe  has  de- 
fcribed another  variety  in  the  Philofophical  tranfa£lions  for  1779 
It  afforded  fixty  parts  carbonate  of  hme,  thirty-five  carbonate  of 
magnefia,  and  three  of  iron. 

The  analyfis  which  I  have  made  of  feveral  limc-ftones  in  our 
province,  conftantly  afforded  magnefia. 

SPECIES        II. 

Lime-flone  and  Barytes. 

Mr.  Kirwan  has  informed  us  that  this  fpecies  is  found  in 
Derbyfinre,  in  the  form  of  a  ftone,  and  likewife  in  the  earthy 
ftate.  It  is  of  a  grey  colour,  and  harder  than  ordinary  lime- 
flones. 

SPECIES       III. 

Carbonate  of  Lime  and  Alumlne. 

Tills  mixture  Is  frequently  met  with.  It  is  commonly  known 
by  the  name  of  Marie.  The  proportions  of  the  two  conftituent 
principles  are  infinitely  various.  It  is  upon  this  proportion  that 
the  diftin^tion  of  fat  marles  and  lean  marles  depends,  and  dif- 
pofes  them  to  ferve  as  manure  for  earths  of  different  kinds. 
The  marles  are  almofl  always  coloured  by  iron. 


Earthy    Mixtures'^  3.09 

.  The^f, appear  to  arife  from  the  decompofition  of  the  natural 
hiixtures^f  chalk  and  clay,  and  contain  more  or  lefs  of  filex  ; 
but  the  anilyfis  which  I  made  fix  years  ago  of  all  the  marles  I 
could  procure,  convinced  me  that  they  were  often  nothing  more 
than  a  mixture  of  clay  and  chalk.  I  have  likewife  found  mag- 
nelia  in  marles,  fometimes  in  the  quantity  of  feventeen  parts  in 
the  hundred  ,  but,  in  general,  they  may  be  confidered  as  formed 
eifentially  by  the  two  earths  here  mentioned. 

Aluminc  is  found  likewife  mixed  with  carbonate  of  lime  in 
marbles.  Mr.  Bayen  has  proved  this  in  the  fecond  volume  of 
the  Journal  de  Phyfique  :  and  I  have  confirmed  the  truth  of  his 
refults  by  the  analyfis  of  feveral  marbles  of  our  province.  It  is 
even  upon  this  principle  that  we  may  account  for  the  greafy 
polifh  which  fome  of  them  take. 

The  very  evident  difference  which  may  be  eftablifhed  between 
the  mixtures  which  form  marie  aiid  marble,  is  that  the  firfi:  is 
the  immediate  produ6l  of  a  decompofition  principally  effe£led  by 
the  alterations  of  the  iron  it  contains  ;  whereas,  the  fecond  is 
produced  by  a  purely  mechanical  mixture  of  two  principles  al- 
ready formed,  which  being  pounded,  and  ground  as  it  were  to- 
gether, form  a  compact,  hard,  clofe  aflemblage,  fufceptible  of 
the  mod  beautiful  polifh. 

SI^ECIES      IV. 

Lime-ftone  and  Sllex. 

This  fpecies  is  not  common.  It  is  known  under  the  name  of 
StellatedSpar,  SternSchoetlof  the  Germans.  Itisopake,  of  a  radi- 
ated texture  or  form.  Mr.  Fitchel  found  it  in  lime-flone  on  the 
Carpathian  mountains.  It  effervefces  with  acids  ;  and,  accord- 
ing to  Mr.  Bindheim,  one  hundred  parts  of  this  ftone  contain 
iixty-fix  carbonate  of  lime,  thirty  filex,  and  three  iron. —  See 
Kir  wan. 

The  mixture  of  the  pulverulent  remains  of  the  primitive  rocks 
ranfportcd  into  our  country  by  the  rivers  which  rife  in  the 
Alps  and  the  Cevennes,  together  with  our  own  calcareous  frag- 
ments, frequently  form  beds  of  a  ftone  of  this  nature.  The  on- 
ly difference  between  them  is,  that  our  mixtures  exhibit  a  con- 
f'jfed  aflemblage  of  all  the  principles  which  belong  to  the  prim- 
itive rocks,  fuch  as  clay,  filex  and  others. 

SPECIES    V. 

^  Liine-flone  and  Bitumen. 

This  mixture  is  known  by  the  name  of  Swine- ftone.      It  a- 
•ounds  in  the  diocefes  of  Alais  and  Uzes  :   I  have  feen  tlie  caU 
2...C 


2lo  Marihy   Mixtures, 

careous  roek  impregitated  with  bitumen  in  an  extent  of  more 
than  three  leagues  diameter.  It  is  even  fo  abundant  in  fome 
parts,  that  it  diftils  through  the  clefts  of  the  rocks,  and  forrna 
italaditous  bitumen,  wliich  the  peafants  collect  to  mark  their 
iheep,  or  to  greafe  their  cart-wheels.  The  heat  of  our  fumraer 
fometimes  foftens  it  to  fuch  a  degree,  that  it  fiows  into  the  roads, 
where  it  adheres  to  and  impedes  the  motion  of  the  fledges  and 
other  carriages. 

In  fome  places  the  ftone  is  fo  well  impregnated  with  bitumen, 
that  it  may  be  wrought ;  but  the  blow  of  a  hamiTfcr  caufes  it 
to  emit  an  abominable  fmell.  Mr.  D'Avejan,  br(hop  of  Alais, 
having  ufed  this  ftone  to  pave  the  apartments  of  his  palace,  the 
friction  and  heat  difcngaged  fo  unpleafant  a  fmell,  that  his  fuc- 
ceffors  were  obliged  to  fubftitute  a  ftone  of  another  kind  in  its 
firead. 

Mr.  De  la  Peyroufe  found  this  ftone  in  large  mafles  near  Saint 
Bcal  in  Comminge,  at  L'Eftagneau,  and  the  mill  of  Langlade. 

SPECIES    vr. 

Lime-Stone  and  Iron. 

Iron  is  almoft  always  a  conftituent  part  of  lime-ftone  ;  but  it 
Ibmetimes  exifts  in  fuch  a  proportion,  that  thefe  mixtures  con- 
flitute  iron  ores.  Mr.  Kirwan  defcribes  two  of  this  nature; 
one  of  which  contains  twenty-five  pounds  of  iron  in  the  quintal, 
and  the  other  ten.  Mr.  Rinmann  has  defcribed  ftala£lites 
which  afford  Iron,  in  the  proportion  of  from  twenty-feven  to 
twenty  pounds  in  the  quintal. 

Calcareous  iron  ores  are  wrought  in  many'  parts  of  our  prov- 
ince. I  have  myfelf  obtained  forty-four  pounds  of  iron  in  the 
qjuintal,  from  a  calcareous  ftbnc  which  abounds  on  the  moun- 
tain of  Frontignan. 

It  is  common  to  find,  in  out  calcareous  mountains,  hematites 
rich  in  iron,  whofe  bafe  is  calcareous  ;  we  find  likewife  fpecies 
of  ludus  of  the  fame  genus,  and  fometimes  even  tufa,  whofe 
formation  arifes  from  waters  loaded  with  iron  and  lime. 

The  fpathofe  iron  ores  are  of  the  fame  clafs  as  thofe  we  have 
juft  treated  of. 

GENUS  ri. 

Barytick  Mixtures. 

Thefe  mixtures  are  very  rare,  becaufe  the  ftone  itfclf  is  fcarce* 
We  (hall  mention  only  two  fpecies. 


Earthy   Mixtures •  2fl 

SPECIES       I. 

Saiphate  of  Barytes,  Petroleum,  Gypfum,  Alum,  and  Silex. — Bcrgmanni 
Sciagr.  f.  90  ;  Kirwan  Min.  p.  (Jo. 

The  name  of  Hepatis  Stone  (Lapis  liepaticus)  has  been  given 
to  this  mixture. 

The  colour  varies  much :  its  texture  is  uniform,  lamellated, 
jfcaly,  or  fparry.     It  takes  the  poHfh  of  alabafter. 

It  forms  a  kind  of  plafter  by  calcination,  and  emits  a  ftrong 
and  fetid  fmell  by  friftion. 

One  hundred  parts  of  this  ftone  contain  thirty-three  barytes, 
thirty-eight  filex,  feventeen  alum,  feven  gypfum,  and  five  petro- 
Jeum. 

SPECIES      JI. 

Carbonate  of  Barytes,  Iron  and  Silex. 

Mr.  Kirwan  has  mentioned  this  ftone  on  the  authority  of  Mr. 
Pindheim.  It  is  infoluble  in  acids,  and  of  a  fparry  texture  ; 
but  he  is  tempted  to  confider  it  as  a  fulphate  of  barytes,  in  con- 
fequence  of  the  property  obferved  by  Mr.  Bindheim,  that  it  be- 
pmes  foluble  in  acids,  after  having  been  calcined  with  oil. 

cfENUS     jn. 
Magnefian  Mixtures. 

All  the  fpecies  comprifed  in  this  genus  poflefs  chara£lers  fuf- 
{iciently  ftriking,  and  eafily  known.  They  are  in  general  greafy 
and  foft  to  the  touch  ;  they  may  be  cut  with  a  knife,  turned 
in  a  lathe,  and  converted  into  any  form  at  pleafure.  They  take 
a  tolerably  good  poHfh.  Some  of  them  are  difpofed  into  fibres  j 
and  thefe  fibres  pofTefs  for  the  moft  part,  a  remarkable  degree 
of  flexibility.  They  ftick  to  the  tongue  like  clays  ;  but  do  not, 
}ike  them,   foften  in  the  water- 

SPECIES       I. 

Pure  Magnefia,  Silex,  and  Alumine, 

SPECIES      II. 

Carbonate  of  Magnefia,  Silex,  and  Alumine. 

The  mixture  of  thefe  three  earthy  principles  forms  \'^\c^ 
^eatites,  pot-ftones,  or  lapides  (illares. 


212  Earthy   Mixtures. 

The  difference  which  analyfis  (hews  between  thefe  two  fpc- 
•ies,  is  ahnoft  entirely  confined  to  the  proportions  qf  their  cor^- 
ftituent  principles.  This  circumftance  might  appear  fufficient 
to  authorize  us  in  confidering  them  only  as  varieties  of  each 
other.  But  as  the  magnefia  13  pure  in  the  talc,  and  in  the  ftatq 
of  carbonates  in  the  fteatices,  we  (hail  coniider  them  as  different 
fpecies. 

1.  Pure  magnefia,  mixed  with  near  twice  its  weight  of  filex, 
and  lefs  than  its  v/eight  of  alumine,  forms  talc.  It  is  of  a  white, 
grey,  yellow,  or  greenifh  colour  ;  foft  and  foapy  to  the  touch, 
compofed  of  tranfparent  laminae  placed  upon  each  other. 
Thefe  laminse  are  more  tender  than  thofe  of  mica  ;  they  lock 
together,  and  are  ufually  divided  into  rhombi,  and  may  be  crufa- 
ed  or  fcratched  with  the  nail. 

Its  fpecifick  gravity  is  2.729. 

Fire  renders  it  more  brittle  and  white  •,  but  it  is  infufible  by 
the  blow-pipe,  and  can  fcarcely  be  fufed  by  the  addition  of  alkali. 
The  borate  pf  foda,  and  the  phofphate  of  urine,  fufe  it  with  a 
flight  eifervefcence. 

Mufcovy  talc  is  compofed  of  large  elaftick,  flexible,  and  tranf- 
parent leaves.  Plates  of  talc  have  been  raifed  in  the  quarries  of 
Vitim  in  Siberia  which  were  eight  feet  fquare. 

2.  Steatites  is  ufually  of  a  greenifh  white  :  it  may  be  eafily 
cut  with  a  knife  ;  and  the  duft  which  is  produced  by  fcraping 
it  does  not  readily  mix  with  water. 

Its  fpecifick  gravity  is  about  2.433. 

It  is  infufible  alone,  hardens  in  the  fire,  and  becomes  white. 
The  borate  of  foda  facilitates  its  fufion  ;  but  foda,  and  the  phof- 
phates  of  urine,  do  not  perfecSfly  diffolve  it. 

According  to  the  analyfis  of  Bergmann,  one  hundred  parts  of 
fteatites  contain  eighty  filex,  feyenteen  magnefia,  in  the  ftate  of 
carbonate,  two  alumine,  and  one  iron. 

Steatites  is  fometimes  found  in  maffes  of  indeterminate  fig- 
ure, and  fometimes  cryftallized,  fuch  as  that  which  Mr.  Ger- 
hard found  at  Raichewtein,  in  Silefia.  Chem.  Ann.  1^85.— 
And  Mr.  Rome  de  Lifle  polfeifes  cryltals  in  hexagonal  laminae 
xefembling  the  leaves  of  mica. 

The  white  fleatites  of  Brianco-n  is  compofed  of  irregular,  fri- 
able, and  femi-tj-anfparent  leaves.  It  often  inclofes  cryltals  of 
fleatites,  of  a  white  or  greenifh  colour,  which  have  the  form  of 
tetrahedral  prifms. 

The  fleatites  of  Corfica  appears  to  be  formed  by  fibres  placed 
befide  each  other.  It  has  a  greenifli  colour,  and  no  perceptible 
degree  of  flexibility. 

The  fleatites  of  Barclth  is  grey,  compaCl  and  folid. 


Earthy   Mixtures,  213 

That  of  Queen  Charlotte's  Bay  in  New-Zealand  is  ftriated, 
green,  femi-tranfparent,  and  fufficiently  hard  to  give  fire  with 
the  fteel. 

3.  The  foap-ftone  of  China  is  a  fteatite,  often  ftriated;  but 
it  is  not  more  uncluous  than  thofe  we  have  already   mentioned. 

The  fteatites  of  Briancon  forms  the  bafis  of  the  vegetable  red. 

4.  The  lapis  ollaris,  or  pot-iiione,  is  only  a  variety  of  the 
fteatites.  It  does  not  appear  to  me  to  differ  from  it  excepting  in 
being  harder. 

Its  colour  is  ufually  greyilh  ;  but  it  is  fometimes  blackened 
by  bitumen. 

Mr.  Gerhard  has  obferved  that  the  lapis  ollaris  of  Swedea 
pfFervefces  with  acids,  and  contains  calcareous  earth  \  But  this 
mixture  is  peculiar  to  it.  Thofe  of  Saxony,  Silefia,  and  Corfica 
(do  not  contain  it.  The  lapis  ollaris  may  be  wrought  with  the 
greateft  facility.  In  the  country  of  the  Grifons,  in  Corfica,  and 
elfewhere,  it  is  turned,  and  formed  into  veiTels  which  refift  the 
fire,  and  have  not  the  inconvenience  of  our  glazed  pottery  ;  it  is 
from  thefe  ufes  that  it  has  obtained  the  name  of  Lapis  Ollaris, 
pot  Stone,  &c. 

SPECIES   iir. 

Pure  Magnefia  combined  with  fomewhat  more  than  its  weight  of  Silex:, 
one  third  of  Alumine,  near  one  third  of  Water,  and  more  or  leis  of  Iron. 

This  mixture  forms  the  ferpentine.  It  has  a  great  analogy 
with  the  preceding  fubftances,  but  is  diftinguilhed  from  them  by 
a  more  evident  degree  of  hardnefs  •,  by  the  property  of  acquiring 
a  more  beautiful  poliih  ;  and  by  a  quantity  of  iron  fufficiently 
confiderable  to  afford  it  a  peculiar  chara6ler. 

The  ferpentine  is  whitilTi,  greenifh,  bluifh,  or  blackifti  ;  fre- 
quently marked  with  black  fpots,  and  fometimes  interfecSled 
with  bands  of  various  colours.  Some  ferpentines  are  even  tranf- 
pareat.  The  Royal  cabinet  of  Mines  poflefs  a  fpecimen  whofe 
ground  is  grey,  and  interfperfed  with  reddifh,  femi-tranfparent, 
and  chatoyant  fpots. 

Serpentine  varies  likewife  in  its  texture. 

It  is  compact,  granulated,  fcaly,  lamellated,  or  fibrous. 

It  takes  the  moft  beautiful  polilli. 

The  iron  it  contains  is  fometimes  obedient  to  the  magnet. 

Itsfpecifick  gravity  is  from  2.4  to  2.65. 

it  melts  in  a  violent  heat  ;  but  a  Icfs  degree  of  fire  hardens  it. 

Mr.  Bayen,  who  has  anaiyfed  the  ferpentine,  found  it  to  con- 
iain,  in  the  hundred  pkrts,  forty-one  filex,  thirty-thiee  magnefia, 
twenty  alumine,  three  ircn^  and  alfo  water. 


2Z4  ^irihy  Mixture^, 

Mr.  Kirwan  has  obferved,  that  the  ferpentinc  of  Corfica,  coft^ 
tained  more  alumine,  and  lefs  filex. 

Mr.  De  Joubert  poiTelTes  a  fpecies  of  ferpentine  which  exhib- 
its fquare  plates  on  its  furface. 

Mr.  Dorthes  has  obferved  feveral  varieties  of  the  ferpentines 
pn  our  Mediterranean  coalts,  and  in  the  river  of  Merault,  whicK. 
leceives  them  from  the  mountains  of  the  Ceyenncs. 

SPECIES      IV. 

Carbonate  of  Magnefia  5  Silex,  Lime,  Aiumine,  and  Iron. 

This  combhiation  exhibits  feveral  varieties,  which  are  knowri 
under  the  name  of  Afbeflos,  Mountain  Cork.  Their  texture 
i"erve3  to  didinguifh  them  ;  but  the  chemical  analylis  confovmds 
them  together,  and  does  not  permit  us  to  allpw  ajiy  other  dif«j 
tinclion  than  that  of  varieties, 

yARIETY   !♦ 
Afoeftos. 

This  (lone  is  ufually  greenifti  j  its  tcxtm*e  is  fometimes  i^-^ 
brouaand  compadt,  and  iometimes  membranaceous. 

Near  JBagneres  de  Bigorre,  in  the  mountains  of  the  environs 
cf  Baiiere,  Melli-s.  Dolomieu  and  La  Peroufe  found  cryftals  of 
aibeitc'S  ill  rhOmboidalparallelopipeds. 

Aibeltos  is  rough  to  the  touch,  brittle  and  rugged.  Its  fpecif- 
ick  gravity  is  from  2.5  to  2.8. 

Fue  renders  it  whiter  and  more  brittle.  It  is  infufible  by  the 
blow'pipe,  according  to  Kirwan  ;  but  the  abbe  Mongez  affirms 
that  aibeftos  and  amianthus  are  fufible,  and  form  an  opake  glo- 
bule, which  becomes  bluiili.  It  is  difficultly  foluble  with  fo- 
da  J  but  more  eafily  with  borate  of  loda  and  the  phofphates  of 
mine. 

x^ccording  to  Bergmann,  the  afbeftos  contains  in  the  quintal 
from  fifty-three  to  (eventy-four  filex,about  fixteen parts  magnefia, 
irom  twelve  to  twenty-eight  carbonate  oi  lime,  from  two  to  {\\ 
alumine,  and  from  one  to  two  iron. 

VARIETY    II. 

Mountain  Cork. 

This  name  has  been  giv^n  on  account  of  a  flight  refemblancc; 
of  this  fubftance  to  cork.  This  Itone  is  very  light,  membrana- 
ceous; Bexiblcj  and  vSwdXhj  of  a  yellow  colour.     It  may  be  more. 


Earthy  Mixtures,  21^ 

€afily  torn  than  broken.     The  diocefe  of  Alais  affords  very  fine 
ipccimens. 

Among  a  very  great  number  of  ftones  of  this  nature,  fubjecl:-. 
ed  to  analyfis  by  the  celebrated  Bergniann,  the  filiceous  earth 
was  always  foirnd  predominant ;  and  after  that  the  magnefian, 
which  was  never  lefs  than  twelve  parts  in  the  hundred,  noF 
more  than  twenty-eight. 

SPECIES      V. 

Carbonate  of  Magndia  and  Lime,  Sulphate  of  Barytes,  Alumine,  and 

Iron. 

This  combination  forms  amianthus.  It  is  compofed  of  long 
flexible  fibres,  parallel  to  each  other,  and  very  foft  to  the  touch. 

They  are  fometimes  very  white,  btrt  often  yellowifii.  The 
filaments  may  be  feparated  and  detached  from  each  other;  and 
may  be  even  twifted  in  any  dire£lion  without  danger  of  break- 
ing them.  Their  flexibility  is  fo  wonderful,  that  they  may  be 
formed  into  cloth.  The  ancients  conftruded  cloths  of  this 
kind,  in  which  they  burned  the  bodies  of  the  dead  -,  and  by  this 
means  the  afties  were  collected  vi^ithout  mixture  of  thofe  of  the 
fuel.        ^  . 

Mr.  Dorthes  found  amianthus  in  tufts  upon  Calcareous  flones 
thrown  up  by  the  fea,  on  which  it  was  fixed  with  plants,  coral- 
lines, gorgonia,  Bcc.  He  believes,  with  reafcn,  that  this  amian- 
thus did  not  originate  upon  the  flones,  but  that  it  was  depofited 
by  the  water.  He  found  like  wife,  on  the  coall,  balls  of  the 
amianthus  of  two  or  three  inches  diameter  imitating  ;egagropiles» 
and  formed  by  the  intertwining  of  the  threads  of  amianthus  ; 
and  covered  with  a  white  tophofe  fubltance,  of  the  nature  of 
that  which  covers  the  gorgonia,  and  is  the  v/ork  of  a  fpecies  of 
fea  animalcule. 

The  fibres  of  amianthus  are  of  various  lengths.  I  have  re- 
ceived ipecimens  from  Corfica,  whofe  filaments  were  very  flex^ 
ible,  and  eight  inches  long.  That  from  the  Pyrenean  mountains 
has  fliOrter  fibres. 

Bergmann  analyfed  an  amianthus  from  the  vicinity  of  Taren- 
to,  of  which  loo  parts  afforded  64  filex,  1 86  iHagnefia,  6.(;lime^ 
^  fulphateof  barytes,  3.3  alumine,  1.2  iron. 

CENUS       17. 

Aluminous  Mixtures. 

Argillaceous  or  aluminous  (lones  are  common  enough. 
They  are  feldom  poffeflcd  of  more  than  a  moderate  degree  of 


2i5  Uarth^  Mixtures.     Potter j. 

hardnefs,  and  are  divilible  in  water.  But  the  mixture  of  their 
principles  is  in  feme  inftances  io  intimate,  that  they  poffefs  t 
very  iirong  degree  of  confidence. 

SPECIES      i. 
Alumine,  Silex,  Carbonate  of  Lime,  and  more  or  lefs  of  Iron. 

We  may  here  place  all  the  varieties  of  clay.  Chemical  anal- 
j^fis  exhibits,  conftantly  enough,  the  principles  whofe  mixture 
forms  this  fpecies  5  but  the  proportions  among  thefe  conftituenC 
principles  vary  fo  much,  that  the  varieties  of  clay  are  almoft  infi- 
rate.  Independent  of  the  principles  above  enumerated,  we 
fometimes  find  lime  combined  with  clay,  and  fometimes  evert 
magnefia  ;  and  it  will  be  eafy  to  form  various  fpecies,  in  pro- 
portion as  the  analyfis  of  thcfe  earths  (hall  become  more  perfect. 

The  argillaceous  mixtures  of  which  we  propofe  at  prefent  to 
fpeak,  are  characterized  by  the  following  properties  : — They  ad- 
here ftronorly  to  the  tongue,  become  dry,  hard,  and  (brink  in  the 
fire;  are  divided,  and  form  a  pafle,  with  water,  in  which  Hate 
they  may  be  eafily  moulded  and  turned,  &C.  The  clays  in 
which  the  filiceous  principle  is  mod  abundant  are  the  dried:, 
adhere  lefs  to  the  tongue,  are  lefs  completely  difFufed  in  water^ 
and  crack  lefs  when  dried  by  the  heat  of  the  fire  or  the  fun. 

Mod  clays  contain  iron  •,  and  this  metal  is  ufually  the  prin- 
ciple of  their  colour.  From  the  brownifli  clay,  in  which  iron 
is  almoft  in  the  native  ftate,  to  the  deepeft  red,  all  the  various 
fliades  are  owing  to  the  feveral  degrees  of  alteration  in  this 
metal.  Thefe  various  changes  are  effected  either  at  the  furface 
of  the  globe  by  the  immediate  aclion  of  the  air,  which  calcines 
the  iron,  or  elfe  in  the  bowels  of  the  earth  :  in  which  laft  cafe, 
the  effects  arife  from  the  decompofition  of  water  and  of  the  py- 
rites. We  may  trace  this  beautiful  work  of  nature  in  feveral 
pyritaceous  (Irata  in  out  province  ;  and  on  this  fubjeft  refer- 
ence may  be  had  to  my  Memoir  upon  the  Brown  Red  (Bruii 
Rouge),  printed  by  Didot  by  order  of  the  province. 

We  fnall  direcl  our  attention  lefs  to  the  feveral  varieties  cf 
clay  than  to  the  ufes  to  which  they  are  applied.  The  firft  o; 
thefe  ufes  is  to  form  the  bafis  of  pottery. 

Several  fpecies  of  pottery  may  be  obferved,  which  nevcrthe^ 
lefs  differ  from  each  other  only  in  the  degree  of  finenefs  of  the 
earths  made  ufe  of,  and  the  care  that  has  been  taken  in  per- 
formin;:^  the  various  manipulations  which  they  undergo. 

I.  The  moft  common  pottery  is  made  with  any  kind  of  clay 
indifcriminately,  which  is  mixed  with  fand,  to  tender  it  more 
P'Xuus,  and  by  thi^  means  more  adapted  to  fupport  the  heat. 


Earthy  Mixtures.     Pottery.  iij 

Thefe  veflels  would  be  penetrable  by  water,  if  they  were  not 
Covered  with  a  glaze. 

The  glazes  of  pottery  are  ufually  made  either  with  the  ful- 
phureous  lead  ore  called  Alquinfoux,  and  in  England,  Potters* 
Lead  Ore,  or  with  the  yellow  copper  ore.  For  this  purpofe, 
thefe  fubllances  are  reduced  to  powder,  mixed  with  water,  and 
the  veiTel,  previouily  dried  by  a  (light  baking,  is  dipped  in  the 
mixture.  The  porous  velfel  abforbs  the  water,  while  its  furface 
becomes  covered  with  the  pounded  ore.  The  vefTel  is  then  car- 
ried to  the  furnace,  and  baked  by  a  heat  which  vitrifies  the  ore 
upon  its  furface  :  and  it  is  this  metallick  glafs  which  forms  the 
glaze  of  the  potters,  and  is  yellow  oir  grcenj  according  to  the  met- 
al made  ufe  of. 

Thefe  glazes  are  all  dangerous  5  becaufe  they  are  foluble  in 
fats,  oils,  acids,  &c. 

The  attention  of  Iritelllgent  manufa£lurers  has  been  long  di- 
redled  to  the  methods  of  fubftituting  in  the  place  of  thefe  glazes, 
others  which  are  not  attended  with  the  fame  danger. 

We  might  after  the  manner  of  the  Engliih,  vitrify  the  furface 
©f  our  pottery  by  means  of  fea  fait  thrown  into  the  fire-place 
when  the  furnace  is  at  a  white  heat  ;  but  this  method  is  im- 
practicable in  molt  of  our  manufactories,  becaufe  our  fires  are 
not  fufliciently  flrong. 

I  have  tried  various  methods  to  glaze  pottery  ;  and  two  a- 
mong  them  have  fucceeded  well  enough  to  juftify  my  publifhing 
them.  The  firft  confifts  in  mixing  the  earth  of  Murivel  in  wa- 
ter, and  dipping  the  pottery  therein  :  this  done,  they  are  fuffer- 
ed  to  dry  :  after  which  they  are  plunged  into  a  fecond  water, 
in  which  levigated  green  glafs  is  mixed.  This  covering  of  vit- 
reous powder  fufes  with  the  clay  of  Murivel  ;  and  the  refult  is 
a  very  fmooth,  very  white,  and  very  cheap  glazing. 

The  fecond   method  confiits  in  immerfing  die  dried  pottery 
:to  a  ftrong  folution    of  fea  fait,   and  afterwards  baking  them. 
ilie  trial  which  I  have  made  in  my  furnaces  gives  me  reafon  to 
expe(fl  that  this  method  may  be  ufed  in  large  works. 

I  have  likewife  obtained  a  very  black  glazing,  by  expofing 
pottery  (trongly  heated  to  the  fumes  of  fea-coal.  I  have  coated 
feveral  vefPjls  in  this  manner,  by  throwing  a  large  quantity  of 
coal  in  powder  into  a  furnace  wherein  the  pottery  \yas  ignited 
to  whitenefs.  The  cffcS:  is  (till  more  complete  when  the  chim- 
neys or  tubes  of  afperation  of  the  furnace  are  at  that  moment 
clofed,  and  kept  fo  for  fome  minutes. 

I  have  given  an  account  of  all  thefe  circumfiances,  and  many 
others,  in  a  work  prefented  to  the  Royal  Society  of  Sciences  of 
Jdontpellier  5  in  which  I  have  proved,  from  the  refults  of  my 
O...D 


I 


21 8  Marihy  Mixtures.     Potterp 

experiirents  in  the  large  way,  that  the  beft  mixture  of  our  owit 
earths  is  capable  of  affording  us  the  mod  beautiful  and  fineft 
pottery  of  every  kind. 

2.  Fayence.*     This  does  not  differ  from  the  pottery  we  have 
here  fpoken  of,  except  in  the  degree  of  finenefs  of  the  earths , 
ufed  for  its  ba{)S,  and  the  nature  of  its  covering  or  glaze. 

The  glazing  of  fayence  is  nothing  elfc,  as  is  well  known,  but 
glafs  rendered  opake  by  means  of  the  oxide  of  tin.  It  is  the 
glafs  called  Enamel. 

To  make  the  fine  white  enamel  of  the  potters,  one  hundred 
pounds  of  lead,  thirty  of  tin,  ten  of  marine  fait,  and  twelve  of 
purified  pot  aih,  are  calcined  together.  This  mixture,  after 
calcination  and  fufion,  produces  a  beautiful  enamel,  which  is 
applied  in  the  fame  manner  as  the  glaze  before  fpoken  of» 

Bernard  de  Palifly  excelled  in  the  art  of  fayencery  \  and  It 
is  to  him  that  we  are  indebted  for  our  firft  acquifitions  in  this 
rrianufa6lure.f 

^  Diftinguifliedby  us  by  the  name  of  Delft  Ware.  T, 
f  I  caniiDt  refill:  my  inclination  to  infert  in  this  place  a  few  circum-^ 
ftances  of  the  life  of  this  great  but  unfortunate  man,  who  lived  in  the  15th 
century.  He  was  a  native  of  the  diocefs  of  Agen,  and  his  firft  employ- 
ment was  that  of  furveyor  or  draftfman  of  plans  :  but  his  tafte  for  natu- 
ral hiftory  led  him  to  abandon  this  employment  :  and  he  travelled  for 
inftradion  over  the  wbole  kingdom,  and  Lower  Germany.  An  acciden- 
tal circunillance  threw  into  his  hands  a-  cap  of  enamelled  pottery;  and, 
from  that  time  his  whole  time  and  fortune  were  taken  up  in  experiments 
on  enamels.  Nothing  can  be  more  interefting  than  the  narrative  which 
he  himfelf  has  given  of  his  labours.  He  exhibits  himfelf  building  and  re- 
building his  furnaces  ;;  always  on  the  eve  of  fuccefs  ;  worn  out  by  labour 
and  misfortune,  the  derifion  of  the  publick  ;  the  object  of  the  angry  re- 
monilrances  of  his  wife  ;  and  reduced  to  burn  the  funiture,  and  even  the 
wood-work  of  his  houfc,  to  keep  his  furnace  going.  His  workman  prefles' 
him  for  money  ;  he  ftrips  hlmfeif,  and  gives  him  his  clothes.  But  at 
length,  by  dint  of  indefatigable  labour,  conftancy,  and  genius,  he  arrived 
at  thedelired  degre'e  of  perfeft^on  ;  which  gained  him  the  elteem  and 
conlideration  of  t+i^^greateft  men  of  his  age.  He  was  the  fiift  who  form- 
ed a  collection  of  natural  hi(iory  at  Paris,  and^  even  gave  ledtures  on  that 
fciencc  ;  receiving  half  a  crown  from  each  of  his  auditors,  under  the  ob- 
ligation of  returning  it  fourfold  if  any  thing  he  taught  fhould  prove  falfe. 
The  high  repataiion  he  acquired,  and  the  obligation  under  which  his  coun- 
trymen Hood  indebted  to  him,  were  not  fufficient  to  defend  him  from  the 
perfecutions  of  the  League  ;  for  Matthew  De  Launay,  one  of  thegreateft 
fanaticks,  caufed  him  to  be  dragged  to  the  Baitile  at  the  age  of  ninety 
years.  He  lignaliled  himfelf  in  liis  prifon  by  ads  of  firmnefs  and  heroifm. 
Henry  the  Third  viiitedhim,  and  reprefenied  his  fituation  in  thefe  words  : 
**  My  good  man,  if  you  cannot  reconcile  yourfcif  to  the  matter  of  relig- 
ion, I  (hall  be  compelled  to  leave  you  in  the  hands  of  my  enemies."— 
PallflV  anfwered,  "  Sire,  1  was  perfeiStly  ready  to  furrender  my  life  for 
**  the'glory  of  GOD.  If  this  a(5tion  could  have  been  accompanied  witb 
"  any  rct^ret,  certainly  it  niuit  havtj  vaniHied  at^ter  hearing  the  grei-t  King. 


Earthy  Mixtures,     Porcelain.  219 

^.  The  fined  pottery  is  known  by  the  name  of  Porcelain  ;  it 
mght  to  be  white,  tranfparent,  and  of  a  fine  grain. 

The  firft  procelains  were  manufa£lured  in   Japan  and  China. 

The  celebrated  Reaumur  firft  undertook  a  capital  feries  of 
experiments  to  imitate  thefe  potteries :  but,  deceived  by  the 
^mi-tranfparence  and  vitreous  apppearance  of  porcelain,  he 
imagined  it  to  be  a  femi-vitrification,  and  attended  only  to  the 
leans  of  flopping  the  procefs  of  vitrification  at  a  certain  ftage 
of  its  effedl:,  or  of  caufing  it  to  become  reverfed.  fie  fucceed- 
cd  in  his  undertaking,  by  filling  bottles  with  fand  and  gypfum, 
and  expofing  them  to  a  potter's  furnace.  I  have  likewife  pro- 
duced the  fame  eflFedl  by  a  very  different  procefs,  though  depen- 
dent on  the  fame  theory.  Y^hen  I  concentrate  my  oil  of  vitriol 
in  the  green  glafs  of  our  manufacture,  that  part  of  the  retorc 
which  is  continually  ftruck  bv  the  rifing  oil  of  vitriol  becomes 
white,  and  lofes  its  tranfparence.  This  phenomenon  conftant- 
Jy  takes  place,  whenever  the  fire  is  raifed  fome  what  more  that) 
uiual.  The  retort  preferves  its  form  ;  but  all  its  alkali  is  ex- 
tracted, and  there  remains  only  the  quartzofe  principle  of  a 
beautiful  white  colour,  fomewhat  cracked  like  the  procelain  of 
Japan.  As  the  decompofition  commences  at  the  interiour  fur- 
face,  which  is  immediately  afted  on  by  the  vapours,  this  furface 
is  frequently  rendered  white,  and  difcoloured  ;  while  the  exte- 
riour  furface  remains  perfedUy  vitreous,  and  exhibits  a  (Inking 
ccntraft.  For,  when  the  interiour  furface  of  the  glafs  is  in- 
fpe£led,  it  prefents  a  white  covering  applied  againfl  a  furface 
of  glafs  J  forming,  by  the  union  of  both,  a  thicknefs  no  greater 
than  that  of  which  retorts  are  ufuallymade. 

Father  Dentrecolles  fent  from  China  the  fubftances  ufed  in 
the  fabrication  of  porcelain  :  they  are  known  by  the  names  of  Ka- 
olin and  Petunce.  Similar  fubftances  were  foon  found  in  France  ; 
and  our  porcelain  manufadories,  in  a  fhort  time,  equalled  the 
moft  beautiful  productions  of  this  kind,  and  even  exceeded  them 
in  the  beauty  of  defign  and  figure.     The  manufactory  of  Seves 

"  of  France  fay,  I  am  compelled.  This,  fire,  is  a  fltuation  to  which  nei- 
"  thcr  yourfeif,  nor  thole  who  force  you  to  aft  contrary  to  your  own  dii- 
"  noHtion,  can  ever  reduce  me  :  becaufe  I  am  prepared  for  death  ;  and 
*'  becaufe  neither  your  whole  people,  nor  your  Majefly,  pofjeis  the 
"  power  of  forcing  a  fimpie  potter  to  bend  his  knee  before  images." — 
Bernard  de  Palifly  was  the  (irft  who  aflirmed  that  calcareous  mountains 
are  the  remains  of "  (hells.  He  has  exhibited  fuch  a  degree  of  intelligence 
and  fagacity  in  all  his  writings,  that  he  deferves  to  be  placed  among 
lihole  great  men  who  are  an  ornament  to  our  nation.  The  very  form 
of  his  works  exhibits  a  proof  of  original  genias.  They  confift  of  di- 
alogues between  Theory  and  Pradice.  Praiftice  is  always  the  inftruc^f- 
or ;  and  Theory  is  reprefented  as  a  icholar,  proud  of  his  own  under- 
uanding  but  indocile  and  ignorant. 


%S,0  Earthy  Mixtures,     Mica. 

is  at  prefent,  without  contradidion,  the  firft  in  the  world.  No^ 
thing  can  equal  the  beauty  of  its  paintings,  the  regularity  of  de- 
fign,  and  the  elegance  of  form,  which  arc  given  to  the  veflels 
produced  in  this  manufactory. 

Four  principal  operations  may  be  diftinguifhe^  in  the  manu- 
facture of  porcelain. —  i.  The  preparation,  the  mixture  of  earths 
and  the  working  of  the  pafte.  2.  The  firft  baking,  which 
forms  the  bifcuit.  3.  The  application  and  fufion  of  the  glaze 
and  covering.  4.  The  art  of  painting,  which  demands  a  third 
baking,  in  order  that  the  colours  may  be  better  combined,  fufed, 
and  amalgamated  with  the  glaze. 

I  have  myfclf  made  very  beautiful  porcelain  with  the  kaoHn, 
■which  is  found  in  veins  in  the  granite  of  St.  Jean  de  Gardon-» 
cnque,  and  the  feld  fpar  fo  common  in  our  mountains  of  Ceven- 
nes. 

,    The  quantity  of  porcelain  which  is  made  in  China  is  immenfe, 
trhere  are  five  hundred  furnaces,  and  near  a  million  of  men, 
employed  at  King-to-ching,  a  province  of  Kian-fi. 

Our  clays  poffefs  other  advantages  likewife :  they  ferve  in 
the  fulling-mills,  to  clean  and  full  piece  goods.  The  beft  ful- 
lers'earth  is  foft  and  foapy. 

The  name  of  tobacco-pipe  clay  is  given  to  a  white  clay, 
•which  preferves  its  whitenefs  in  the  fire,  and  refifts  a  violeirit 
heat. 

The  fcaled  earth,  or  terrse  flgalatse,  are  clays  upon  which 
fuperftition  has  beftowed  chimerical  virtues.  They  are  im- 
prefTed  with  a  feal,  for  the  purpol'e  of  deceiving  the  pubhck 
with  greater  certainty  and  effrontery. 

Almoft  all  the  marks,  more  efpecially  thofe  which  are  found 
'  in  ftrata,  appear  to  me  to  be    compofed  of  the  fame  principles. 

Much  variation  prevails  with  refpeft  to  the  proportion  of 
thefe  conftituent  principles,  and  more  efpecially  with  regard  \q 
the  clay  which  predominates. 

SPECIES       II. 

Alumine,  Silex,  Pure  Magnefia,  and  Iron. 

Mica,  which  refults  from  the  mixture  of  thefe  principles,  ha^ 
been  improperly  confounded  with  talc.  Mica  is  foft  to  the 
touch,  but  not  greafy  like  talc.  It  poflefTes  in  general  a  more 
brilliant  and  lefs  earthy    colour,  if  I    may  ufe  thefe  exprefTions. 

The  moft  ufual  colour  of  mica  is  white  or  yellow,  inclining 
to  red  ;  but  it  has  been  found  of  a  greenifh  red,  brown,  and 
pther  colours. 

Its  texture  likewife  varies  :  it  is  fcaly,  lamcllated,  or  flriated. 


Earthy  Mixtures.     Horn-hlende,  'xn 

It  fometimes  exhibits  the  form  of  a  fegment  of  an  hexago- 
nal prifm. 

It  is  ufually  found  mixed  with  feld  fpar,  quartz,  fchorl,  &:u"» 
it  almolt  always  exiRs  in  the  primitive  rocks.  Its  fpecifick 
*rravity  is  from  2.535  ^^  3.000  when  charged  with  iron.— - 
Kirwan. 

The  colourlefs  m.ica  is  infufible.  It  is  only  partially  foluble 
in  foda,  in  which  it  becomes  divided  with  efFervefcenCe  ;  it  fu- 
ies  in  the  borate  of  foda,  and  in  the  phofphate  of  urine,  with 
fcarcely  any  efFervefcence. 

The  coloured  micas  are  fufible. — See  de  Sauflure. 

The  fragments  of  mica  are  employed,  under  the  name  of 
Cats  Gold  or  Silver,  according  to  the  colour,  as  a  fand  for  dry- 
ing ink  upon  paper. 

Its  yellow  colour,  which  confiderably  refembles  that  of  gold, 
often  deceives  the  ignorant,  who  fuppofe  that  they  have  dif- 
covered  a  mine  of  this  precious  metal  when  they  find  a  few 
pieces  of  this  ftone. 

Mr  Kirwan  obtained  from  one  hundred  parts  of  colourlefs 
inica,  thirty-eight  filex,  twenty-eight  alumine,  twenty  magnefia, 
^nd  fourteen  o^ide  of  iron. 

SPECIES      III. 

Alumine,  Silex,  Magnefia,  Lime,  and  Iron. 

The  mixture  of  thefe  principles  forms  the  horn- ftone, -or 
horn-blende  of  the  Germans.  This  ftone  has  a  clofe  grain,  is 
dilRcultly  pulverized,  and  is  liightly  flattened  under  the  hammer. 

Its  colour  varies,  which  is  either  black  or  of  a  greenifti  grey  ; 
and  its  texture  is  in  general  either  lameliated  or  ftriated. 

Its  general  charadlers  are,  partial  folubility  in  acids  without 
efFervefcence  -,  a  degree  of  hardnels  which  never  amounts  to 
that  of  affording  fire  with  the  fteel ;  a  i'pecifick  gravity  never 
iefs  than  2.66,  and  frequently  as  high  as  3.88  j  a  ilrong  earthy 
fmell,  which  it  emits  when  breathed  upon,  or  is  moiftened  with 
hot  water  ;  a  tenacity  under  the  peftle,  &c.— See  Kirwan,  who 
diftinguifhes  two  varieties. 

VARIETY  I. 

Black  Horne-Stone,  Lapis  Corneus  Nitens  Wallerii 

Its  texture  is  either  lameliated  or  grained.  In  the  firft  cafe 
\t  is  fometimes  fo  foft  as  to  be  capable  of  being  fcratched  with  a 
nail.  Its  furlace  is  frequently  of  a  ftiining  greafy  appearance  5 
^nd  its  fpecifick  gravity  is  f*om  3.6  to  3.8 S. 


222  Earthy  Mixtures,     Slate^ 

Mr.  Klrvvan  found  that  the  lamellated  fort  contains  thirfy- 
feven  parts  filex,  twenty-two  clay,  fixteen  magnefia  two  Jimt, 
and  twenty-three  oxide  of  iron. 


VARIETY       If. 

Horn-ftoneofa  Greenlfn  Grey  Colour, 
This  variety  is  either  of  a  granulated  or  ftriated  texture.    Mr. 
ICirwan  found  its  fpecifick  gravity  to  be  2.683  ;    it   is   harder, 
than  the  preceding. 

The  pale  greenifh  hone  is  of  this  quality.  Its  grain  is  clofe  5 
it  emits  an  earthy  fmell,  does  not  effervefce  with  acids,  nor 
ilrike  fire  with  fteel.  It  contains,  according  to  Kirwan,  fixty- 
five  parts  of  filex  to  the  hundred,  and  its  fpecifick  gravity  i& 
0.664. 

gPEC^ES      jy. 

Alumine,  Sitcx,  Carbonate  of  Magnefia,  and  of  Lime  with  Iron, 

This  fpecies,  which  comprehends  the  flate  or  fchiflus,  does 
not  appear  to  differ  eflentially  from  the  preceding,  fince  its  prin- 
ciples are  the  fame,  arid  there  is  no  other  difference  excepting 
what  depends  on  the  (late  of  the  lime  and  magnefia  ;  which  in 
this  lad  efiervefces  flightly  with  acids,  according  to  Kirwan. 

The  fiate  is  an  argillaceous  flone,  whofe  principal  chara(Eler 
is  that  of  being  divifible  into  very  thin  plates,  capable  of  being 
wrought,  and  of  receiving  a  certain  polilTi. 

The  colour  of  the  flate  is  blue,  of  feveral  degrees  of  intenfity  ^ 
but  this  colour  varies,  and  exhibits  the  following  Tnades. 

VARIETY       I. 

Bluifh  Purple  Slate. 

This  is  brittle,  and  of  a  lamellated  texture  ;  does  nof  give 
fire  with  the  fteel  j  its  fpecifick  gravity  is  2.876  j  it  affords  a 
very  clear  and  filvery  found,  when  divided  into  plates  of  an  uni- 
form thicknefs  ;  it  flightly  effervefces  with  acids  when  it  is  re- 
duced into  powder,  but  not  elfe. 

It  forms  black  fcorae  in  a  llrong  fire.  Soda  affiils  its  fufion, 
and  it  is  fufed  ftill  more  eafily  with  the  borate  of  foda. 

From  one  hundred  grains  of  this  flate  Mr.  Kirwan  obtained 
forty-fix  filex,  twenty-fix  alumine,  eight  magnefia,  four  carbon- 
ate of  lime,  and  fourteen  iron. 

Slates  are  ufed  to  form  tablets,  and  to  cover  the  roofs  of  hoUfes» 


Earthy  Mixtures,      B!ah\  il^ 


VARIETY       1 1 . 

Black  Slate. 


This  receives  a  confiderably  fine  polilh  when  rubbed.      The 
"^wder  which  is  detached  is  white,  and  flightly  eiFervefces  witli 
acids. 


VARIETY      III. 

Blue  Slate, 

The  blue  Date  contains  lefs  iron  than  the  firft  variety,  ft  is 
tifually  hard,  and  of  a  very  fine  grain. 

Variety     iv. 

^late  of  a  pale  White  Goloar.. 

It  is  lefs  martial  than  the  other  varieties,  and  is  more  difficult-^ 
ly  vitrified. 
.  Slates  are  ufed  to  form  tablets,  and  to  cover  tlibe  roofs  of  houfes. 

SPECIES      V. 

Alumine,  Silex,  Pyrites  or  Sulphure  of  Iron  and  Carbonate  of  Lime  and 

ofMagneda. 

Tlie  fchiftus  which  refulrs  from  this  combinatton  is  known  by 
the  name  of  Pyritous  Schiftus. 

The  pyrites  arc  fometimes  dlfperfed  in  the  mafs,  in  the  form 
of  cubical  cryftals.  Somedmes  they  are  difcovered  only  by  an- 
alyfis,  or  by  the  fpontaneous  decompoiition  of  the  (tone. 

The  mountains  which  afford  this  fchifti  appear  to  me  to  be 
marine  depoiitions,  Imprefiions  of  leaves,  of  fifiies,  and  other 
characters,  are  frequently  obferved,  wliich  leaves  no  doubt  of 
their  origin. 

The  pyrites  foon  efRorefce  when  the  concurrence  of  air  and 
water  afiilts  their  decompofition  v  and  the  refults  then  are  ful- 
phurick  fahs,  with  bafes  of  magnelia,  alumine,  iron  and  lime. 
When  the  fulphate  of  alumine  predominates,  it  is  called  alu- 
minous fcluftus.  Mod  of  the  alum  ores  wrought  in  Europe  are 
of  this  nature.  We  have  feveral  in  Provence  which  might  be 
wrought  ;  the  fchifti  of  Vebron  in  the  Gavandan,  thofe  of 
Curvaile  in  the  Albtgeois,  afford  much  alum  by  their  decompo- 
fition. 


t24  BtirtJyj  Mixlnres.      Slatii 

When  die  magnefian  principle  prevails,  the  efflorefcence  coil  - 
lifts  of  Epfom  fait,  1  have  difcovered  a  mountain  of  this  kind 
in  Rouergue,  in  the  neighbourhood  of  Saint  Michael. 

Thefe  efflorefcences  of  alum  or  Epfom  fait  are  always  more 
or  lefs  abundantly  mixed  with  the  fulphates  of  iron  and  of  lime  ; 
Hecaufe  the  fulphurick  acid,  which  is  formed  by  the  decompo- 
iition  of  the  pyrites,  attacks  and  diffolves  all  the  principles  con- 
tained in  the  fchidus. 

The  decompofition  of  tlitk  pyrites  rhay  be  haftened  by  expo-' 
fure  to  air,   calcination,  &c. 


SPECIES  vr. 

Ahimine,  Silex,  the  Carbonate  of  Lime  and  of  Magnefia,   the  Sulphure 
of  Iron,  and  Bitumen. 

This  fchiftus  does  not  differ  from  tlie  foregoing,  excepting  in 
confequence  of  its  being  impregnated  with  bitumen.  It  is  ufu- 
ally  of  a  bljck  colour,  which  it  owes  to  its  bituminous  princi- 
ple. Its  confi {Veiice  is  various  5  it  is  fometlmes  divifible  in  flakes, 
and,  its  furface  is  either  fmooth  or  rugj:;ed. 

Thefe  are  the  fchifli  which  ufually  form  the  focus  of  volca- 
noes. When  their  decompofition  is  favoured  by  air  or  water  a 
prodigious  heat  is  excited »  hydrogenous  gas  is  produced,  which 
exerts  itfelf  agdinil  the  furrounding  obltacles,  and  takes  fire 
•when  it  comes  in  contaft  with  the  air.  It  is  this  inteltine  la- 
bour which  occafjons  the  (hocks  and  tremulous;  agitations  that 
precede  the  eruptions  of  volcanoes.  The  action  of  volcanoes 
muft  be  more  lafting  and  terrible,  in  proportion  as  the  quantity 
of  aliment  and  the  focus  are  the  more  confvderable. 

We  might,  in  ftri^lnefs,  place  the  pit-coals  here,  as  they  do 
not  differ  from  this  fchillus  but  in  their  greater  abundance  of  the 
bituminous  principle.  We  daily  obferve  fpontaneous  inflam- 
mation to  take  place  in  heaps  of  pyritous  coal,  and  the  fame 
cffed-  happens  even  in  the  midft,  of  the  veins  which  are  wrought, 
f^everal  examples  of  this  may  be  pointed  out  in  the  kingdom  of 
France.  There  even  exifts  at  Cranfack  in  Rouergue  a  true 
burning  volcano.  The  mountain  which  contains  the  coal  is 
pj-odigioufly  hot,  and  flames  are  perceived  from  time  to  time  o« 
its  fummit,  which  iffue  from  its  bowels.  All  thefe  phenomena 
depend  on  the  fame  caufe  ;  and  from  the  fmall  artiticial  volca- 
no of  Lemery,  to  the  terrible  eruptions  of  Vefuvius,  there  is  no 
ctther  difference   than-  what   confifts  in  ihe  magnitude  of  the 


d 


Earthy  Mixtures,     Zeoliie,  ^1% 

When  the  earthy  and   metallick  principles,  which  form  the 
"h^ifis  of  bituminous  fchilli,  are  ilrongly  heated,  and  almoft  vitri- 
ied  by  the  fire  which  produces  their  decompofition,  they  confti- 
:ut€  yelcanick  produdls. 

SPECIES      VII. 
Ahimine,  Silex,  Lime,  and  Water, 

This  ftone  which  is  called  Zeolite,  was  unknown  to  mineral* 
^gifts  before  the  celebrated  Cronftedt  gave  a  defcription  of  it. 

It  is  ufually  of  a  femi-tranfparent  white  :  but  this  colour  is 
fometimes  altered  by  metallick  mixtures,  and  then  it  aflumes  all 
kinds  of  tinges. 

The  name  of  Zeolite  has  been  given  to  it  on  account  of  its 
property  of  forming  a  jelly  with  acids.  This  property  has  even 
been  confidered  as  exclufive  and  chara£leriftick.  But  Mr.  Swab 
has  very  juftly  obferved,  in  the  year  1758,  that  all  zeolites  do 
not  poflefs  this  property  ;  and  Mr.  Pelletier  has  proved  in  the 
twentieth  volume  of  the  journal  de  Phyfique  that  this  property- 
is  not  even  peculiar  to  zeolites. 

The  €xi{lence  of  zeolites  in  certain  lavas  has  induced  fome 
natCiralifts  to  confider  them  as  produced  by  the  decompofition  of 
volcanick  earths. 

The  moft  beautiful  zeolites  come  to  us  from  the  iflands  of 
Ferro  near  Iceland.  The  form  of  this  ftone  is  conftant.  The 
radii  which  compofe  it  diverge  as  it  were  from  a  central  point, 
and  are  difpofed  after  the  manner  of  a  fan.  The  radius  which 
terminates  at  the  external  furface,  is  found  to  exhibit  a  trihedral 
or  tetrahedral  pyramid. 

The  white  zeolite  affe(fl:s  two  principal  forms,  the  cube,  and 
the  tetrahedral  prifm,  fometimes  flattened,  and  terminated  by  aa 
obtufe  tetrahedral  pyramid. 

Its  fpecifick  gravity  is  from  2.1  to  3.15. 

The  zeolite,  expofed  to  a  ilrong  heat,  dilates,  and  fwells  morer 
or  lefs,  according  to  the  proportion  of  water  it  contains,  and 
at  length  melts  into  a  porous  fcoria.  Soda  fufes  with  it  with 
effervefcence  ;  the  borate  of  foda  diflblves  it  more  difficultly  ; 
and  the  phofphates  of  urine  have  fcarcely  any  aflion  upon  it. 

Bergmann  obtained  from  one  hundred  parts  of  the  red  zeolite 
of  Adclfort,  83  filex,  9.5  alumine,  6.5  pure-lime,  and  4  water. 
Letters  on  Iceland,  p.  370. 

The  white  zeolite  of  Ferro  contains,  accordlngf    to  Pelletier, 
fifty  fdex,  twenty  alumine,  eight  lime,  and  twenty-two  water. — . 
Journal  de  Phyfique,  t.  xx, 
2...E 


L 


22'6  Earthy  Mixtures.     Gems, 

Meyer  obtained  from  a  radiated  zeolite  51.33  filex,  17.5 
alumine,  6.66  lime,  17.5  water. 

Mr.  Kirwan  rightly  obferves,  that  the  cryftallized  fpecies  con- 
tain more  water  than  the  others. 

GENUS    v: 

Siliceous  Mixtures. 

We  (hall  place  in-  this  genus  all  the  flones.  which  give  fire 
with  the  fteel. 

SPECIES     r. 
Silex,  .Alumine,  Lime,  and  Iron  intimately  combined. 

The  mixture  of  thefe  feveral  earths  forms  the  precious  ftones' 
or  gems.  All  the  varieties  of  gems  depend  on  their  colour, 
hardnefs,  brilliancy,  weight,  the  proportion  of  their  conftituent 
parts,   and  their  more  or  lefs  intimate  combination. 

The  numerous  experiments  of  the  celebrated  Bergmann  an 
precious  {tones,  have  thrown  the  greatefl  light  on  their  nature 
and  compofition.  The  analyfes  of  MefTrs.  Gerhard,  Achard, 
Sec.  by  exhibiting  a  {lri£l  identity  of  principles,  have  confirmed 
to  us  the  refults  of  the  famous  Swedilh  chemifl: ;  and  it  appears 
that  no  reafonable  doubt  can  now  be  formed  againft  thofe  prin- 
ciples* 

As  gems  or  precious  (tones  are  diftinguiftied  in  commerce  by 
their  colour,  we  ihall  preferve  this  eltablifhed  diftindlion. 

DIVISION      I. 
Red  Gems  or  Precious  Stones — the  Ruby,  Garnet,  Sec. 

I.  The  ruby  is  a  precious  (tone  of  a  fiery  red  colour,  electri- 
cal by  friction,  giving  fire  with  (teel,  the  mo(t  ponderous  and 
the  hardefb  of  precious  (tones.  It  cryftallizes  in  long  hexahe- 
dral  pyramids  applied  bafc  to  bafe,  without  an  intermediate 
prifm. 

Its  fpeclfick  gravity  is  from  3.i§  to  4.283.  It  is  not  vitrified 
in  the  fire  without  addition  ;  and  ""even  reri(ts  the  adtion  of  the 
burning  mirror.  Flame  urged  by  vital  air  eafily  fufes  it.  It 
does  notlofe  its  colour  at  the  degree  of  heat  which  is  fufficient 
to  melt  iron.  The  borate  of  Soda  and  the  phofphates  of  urine 
fufe  it. 

One  hundred  parts  of  ruby  contain,  according  to  Bergmann, 
forty  alumine,  thirty-nine  filex,  nine  lime,  and  ten  ironi 


Earthy  Mixtures,     Gems.  227 

The  lapidaries,  with   whom  harclnefs  and  tranfparency  are 

iie  principal  charafters  of  (tones,  diftinguifh  rubies  of  different 

tcblours,;  aind  the  inhabitants  of  Pegu,  who confider  the  modifica- 

l^^ttons  of  the  colouring  principle  as  different  degrees  of  maturity, 

^^fcnfound  the  topaz  and  the  fapphire  under    the  name  of  rubies, 

^Hf  which  they  make  three  varieties. 

^^P  The  name  of  Spinelle  ruby,  or  Balaisruby,  is  given  to  the  fame 
^tdnd  of  ftone,  accordingly  as  its  colour  is  of  a  pale  or  a  deep  red. 
This  ruby  cryftallizes  in  octahedrons  and  has  a  lefs  fpccifick 
gravity  than  the  oriental  ruby. 

2.  The  garnet  is  tranfparent  when  it  is  not  over-loaded  with 
vkon.  It  is  in  general  obedient  to  the  magnet,  and  of  a  yellow- 
ifh  red.  The  forms  of  the  garnet  appear  to  be  derived  from  the 
rhomboidal  parallelepiped,   terminating  in  fix  equal  rhombufes. 

They  vary  prodigioufly  in  colour,  and  thefe  varieties  are — i. 
The  red,  or  the  carbuncle  of  Theophraftus,  according  to  Hill  : 
iit  has  a  deep  red  colour.     2.  The  Syrian  garnet,  of  a  deep  red, 
,ilightly  tinged  with  yellow.     3.  The  violet  garnet,  of  a  beauti- 
ful red  mixed  with  violet. 

All  the  garnets,  whether  denominated  oriental  or  occidental, 
.rank  in  one  of  thefe  three  claffes. 

Garnets  change  in  the  fire  into  an  enamel  of  a  blackifti  red. 
They  are  ftrongly  attacked  by  the  borate  of  foda,  and  the  phof- 
phates  of  urine. 

Garnet  is  found  in  fmall  grains  in  fand  ftone  (gres)  or  in 
fchiftus. 

The  texture  of  the  garnet  is  lamellated,  and  its  fra£ture  vitre- 
ous. 

Its  hardnefs  is  inferidur  to  that  of  other  gems,  hut  it  exceeds 
"hat  of  rock  cryftal. 

Its  fpecifick  gravity  is  from  3.6  to  4.188. 

One  hundred  parts  of  garnet  contain,  according  to  Mr.  A- 
chard,  48.3  filex,  30  clay,  11.6  lime,  10  iron. 

They  fome  times  contain  tin,  or  even  lead  ;  but  thisis  fet- 
dom. — Bergmann, 

DIVISION      I-I. 

Yellow  Gems  or  precious  ftones — the  Topaz,  the  Hyacinth,  &c. 

I .  The  topaz  is  of  a  gold  colour.  "VVe  arc  acquainted  with 
itwo  principal  varieties  :  the  «tcidental  or  BraziHan  topaz,  which 
has  the  beautiful  deep  yellow  colour  of  gold ;  and  the  oriental 
whofe  colour  is  lighter.  The  Saxon  topaz  refembles  the  latter. 
The  oriental  topaz  lofes  neither  its  colour  nor  its  tranfparen- 
cy in  the  porcelain  furnace.  The  Brazilian  topaz  lofes  its  pol- 
iihj  its  hardnefs,  and  its  tranfparency,  but  without  melting. 


228  Marthy  Mixtures.     Gems, 

The  oriental  topaz  afFe£ls  the  oi^^hedral  form. 

The  BrazUian  topaz  cryflal.lizes  in  rhomboidal  tetahedral 
pr»fms,  grooved  longitudnially.  They  are  terminated  by  two 
tetrahedral  pyramids  with  fmooth  triangular  faces. 

The  Saxon  topaz  exhibits  long  fubodtahedral  prifms,  termi- 
nated by  hexakedral  pyramids  more  or  lefs  truncated  at  their  bafe. 

The  fpeciEck  gravity  of  the  oriental  topaz  is  to  that  of  water 
as  40.106  to  10.000  ;  that  of  the  Brazilian  topaz  is  as  35.365; 
to  10.000. — See  Briflbn. 

The  anal yfis  of  one  hundred  parts  of  topaz  afibrded  Berg- 
snann  forty-fix  clay,  thirty-nine  filex,  eight  carbonate  of  linie^ 
and  fix  iron. 

2.  The  orieatal  hyacinth  is  of  a  reddifh  yellow  colour. 

It  is  ufually  cryftalHzed  in  the  form  of  a  reclangular  tetrahe- 
dral prifm,  terminated  by  two  quadrangular  pyramids  with 
rhombick  faces. 

It  lofes  the  brilliancy  of  its  colours  by  the  fire.  M.  Mongez 
confiders  it  as  infufible  by  the  blow-pipe.  Mr.  Achard  affirms 
that  he  fufed  it  ia  a  wind  furnace. 

One  hundred  parts  afforded  Bergmann  forty  alumine,  twenty- 
five  filex,  twenty  carbonate  of  lime,  and  thirteen  iron.  That 
of  which  Mr.  Achard  has  given  the  analyfes  contained  41.33 
alumine,  21.66  filex,  20  carbonate  of  lime   13.33.  ^'^^"' 

Hyacinths  are  found  in  Poland,  in  Bohemia  in  S,axpny,  Ve« 
lay,  &c. 

The  hyacinth,  rendered  white  by  fire,  is  known  by  the  name 
of  Jargon.  According  to  Mr.  Lavoifier,  the  hyacinth  of  Puy 
^n  Yelay  becomes  white  in  fire  urged  by  vital  air. 

Its  fpecifick  gravity,  compared  with  that  of  water,  is  as  36.87^ 
to*  10. 005. — See  Briflpn. 

DIVISION       III, 
Green  Gems — the  Emerald,  Chrysolite,  Beryl,  &c. 

1.  The  Peruvian  emerald  is  of  a  green  colour,  ele<^rical  by, 
fri6lion,  and  cryftallized  in  hexahedral  prifms,  truncated  flat  at 
each  extremity. 

The  jafpers,  or  green  fchorles,  which  are  called  prafe  or  moth- 
er emerald,  have  often  been  confounded  with  the  emerald. 

Cryftals  of  emeralds  are  frequently  found  inferted  in  the 
gangues  of  quartz,  and  even  of  fpar. 

According  to  Mr.  Sage,  the  more  transparent  emeralds  are, 
the  lefs  their  colour  is  changed  in  the  fire.  They  become  opake^ 
;and  of  a  greenifh  white.  There  are  fome  which  are  reduced 
^0  enamel  at  their  furface. 


( 


Earthy  Mixtures.     Gems,  22iJ 

Mr.  Darcet  affirms,  that  in  his  experiments  the  emerald  loft 
tb  traniparency,  and  moft  of  its  colour,  but  that  its  form  waa 
|,ot  changed.  In  the  experiments  at  Vienna  in  Auftria,  the 
lerald  melted  in  twenty-four  hours  v  and  at  Florence  it  was 
)eedi]y  fufed  by  the  burning  mirror.  Mr.  De  Sauflure  fufed 
by  the  blow-pipe  into  a  compact  grey  glais  ;  and  Mr.  Lavoifier, 
Fith  a  ftream  of  vital  air,  fuied  it  into  an  opake  milky  bubble^, 
rhofe  internal  part  was  grcenilli. 
Its  fpeciiick  gravity,  compared  with  that  of  water,  is.  in  the 
j)roportion  of  27.755  to  10.000. 

One  hundred  parts  afforded  Bergmann  fixty  alumine,  twenty- 
four  filex,  eight  lime,  fix  iron. 

Achard  obtained  60  alumine,  21.26  filex,  8.33  lime,  and  5 
iron. 

The  emeralds  which  come  from  America  are  called  occident- 
•al.  Peru  and  the  Brazils  afford  the  moft  beautiful :  they  may 
be  diftinguifhed  by  the  colour  ;  that  of  Peru  is  of  a  fatin  colour 
or  appearance  ,  the  colour  of  the  Brazilian  is  lefs  lively. 

The  emerald  is  the  fofteft  of  gems,  and  may  be  fcratchcd 
by  the  topaz,  the  fapphire,  &c. 

2.  The  chryfolite  ox  peridot  is  of  a  green  colour,  flightly  in? 
dining  to  yellow. 

Its  form  is  that  of  an  hexahedral  py  imid  with  unequal  fides, 
frequently  flriated,  and  terminating  in  two  hexahedral  pyramids, 
Mr.  Sage  affirms  that  this  ftone  fuffers  no  alteration  in  the 
moft  violent  heat,  its  colour  not  being  fo  much  as  altered  :  and 
the  fame  chemift  pretends  that  Wallerius  did  not  operate  on  a 
true  chryfolite,  becaufe  he  affirms  that  it  loft  its  colour.  McfTrs. 
Lavoifier  and  Erhmann  fufed  it  into  a  white,  dirty,  dull-colour- 
<;d  glafs,  by  the  alBftance  of  vital  air. 

The  fpeciiick  gravity  of  the  Brazilian  chryfolite  is  in  propor- 
tion to  that  of  water  as  26.923  to  1 0.000. — BriiTon. 

MafTes  of  granulated  chryfolite  of  various  fliades  of  green  col- 
our are  found  in  the  prifmatick  baraltes,  and  in  feveral  other 
volcanick  produces. 

Thefe  chryfolites  are  common  in  the  volcanoes  of  our  province. 
Mr.  Sage  received  from  Auvergne  an  hexagonal  prifm  fix  inches 
in  diaifieter,  formed  by  the  union  of  chryfolites  of  different  col-^ 
ours. 

3.  The  beryl,  or  aqua  marina,  is  of  a  very  bluifli  green. 
The  Saxon  beryl,  as  well  as  that  of  Siberia,  fent  to  Mr.  Sage 
by  Mr.  Pallas,  exhibits  hexahedral,  flriated,  truncated  prifms,  of 
a  lamellated  texture. 

The  pure  beryl  decrepitates  in  the  fire,  lofes  its  tranfparcnce, 
an4  is  fufible  by  the  blow-pipe. 


23®  Earthy  Mixtures,     Cr^alu 

Its  fpeclfick  gravity,  in  proportion  to  water,  ifi  as  35.489  t® 
io.ooo,  for  the  oriental  aqua  marina  ;  and  27.227  to  io,ooq 
for  the  occidental. — Briflbn, 

A  blue  aqua  marina,  in  long,  flattened,  tetrahedral  prifmsj 
•grooved  longitudinally,  and  united  fideways,  is  found  among 
•the  granites  of  Spain,  and  on  the  declivity  of  Saint  Symphorien, 
jjnear  Lyon.  This  Hone  is  very  common  at  Baltimore  in  Amer- 
;ica. 

DIVISION-       IV. 

Blue  Gems — Sapphire. 

The  colour  of  the  fapphire  is  a  Iky-blue.  The  fapphires  of  t:he 
brook  d'Expailly  have  a  green  tinge,  and  change  in  the  fire  in 
The  fame  mann&r  as  thofe  of  the  Brazils  ;  wliereas  the  oriental 
iiapphire  is  not  changed  in  our  ordinary  furnaces.  Mr.  Erh- 
luann  caufed  the  clear  oriental  fapphire,  and  of  a  perfe6):  blue> 
to  run  into  an  opake  white  globule  by  fne  excited  by  the  ftream 
of  oxigeue. 

The  experiments  of  Meflrs.  Achard,  Sage,  D'Arcet,  Erlimann^, 
3iiavoifier,  Geyx,  Q^ift,  &c.  exhibit  a  variety  of  refults  in  the 
analyfes  of  gems  by  fire,  which  can  be  attributed  only  to  the 
tnanner  in  which  they  applied  it  ;  and  more  efpecially  to  the 
very  variable  nature  of  the  ftoncs  upon  which  they  made  their 
experiments. 

The  oriental  fapphire,  and  that  of  Puy,  have  the  form  of  two 
^cry  long  hexahedral  pyramids  joined  and  oppofed  bafe  to  bafe, 
^thout  any  intermediate  prifm.  Mr.  Sage,  faw  a  fapphire  in  a 
xhomboidal  cube,  or  fix  fided  figure. 

The  fapphire  analyfed  by  Bergmann  afforded  him  per  quintal^ 
"58  parts  alumine,  35  filex,  5  lime,  and  2  iron. 

Mr.  Achard  obtained  from  his  anaiyfis  58.33  alumine,  33.33 
filex,  6.66  lime   and  3.33  iron. 

The  fpecifick  gravity  of  the  fapphire  of  Puy  is  in  proportion 
to  water  as  40.769  to  10.000  ;  that  of  the  white  oriental  fap- 
phire is  as  39.91 1  ;  and  that   of^  the   Brazilian  fapphire   is  as 

SPECIES         II. 

!Silex,  fometimes  pure,  but  cFtener  mixed  with  a  very  finall  quantity  of 
Alumine,  Lime,  and  Iron. 

.   .  This  fpecies  efTentially  comprehends  quartz  and  rock  cryflal. 

The  name  of  Quartz  is  given  to  the  opaque,  or  irregularly^ 

^gured  vitrifiable  Itonc  j  and  that  of  Rock  Cryltal  to  the  fame 


Earthy  MixtureT.     CryJIab,  2':^  I 

flone  cryftallized.     As  the  principles  are  nearly  the  fame,  this 

Iircumftance  naturally  eftabliflies  a  divinon  of  thefe  ftones  into 
ivo  claiTes. 


PIVISION       I 
Rock-Cryflal. 


Rock  cryftal  Is  a  (lone  which  exhibits  filex  In  a  flate  more 
nearly  approaching  to  purity  than  in  any  other  natural  fubflance 
yet  obferved.  Mr.  Gerhard  has  even  found  fpecimens  perfe£l- 
ly  pure  ;  but  one  hundred  parts  of  cryftal,  ftri^lly  analyfed  hj 
Bergmann,  afforded  him  ninety-three  parts  filex,  {ix  alumine, 
and  one  lime. 

The  ordinary  form-  of  rock  crydal  is  that  of  an  hexahedral 
prifm,  terminated  by  pyramids  of  an  equal  number  of  fides^ 
The  varieties  of  the  feveral  cryftals  may  be  reduced  to  this  geo- 
metrical form. — Confult  Rome  de  Lifle. 

Quartz  cryftallizes  likewife  in  cubes.  This  form  exifts  in  va- 
rious fpecimens  in  the  cabinets  of  Germany  ;  and  Mr.  Macquart 
brought  a  fpecimen  with  him  to  France. 

The  formation  of  this  cryftal  appears  to  be  owing  to  water, 
for  we  often  find  this  fluid  in  the  internal  part  of  cryflals  ;  and 
they  are  evidently  formed  in  the  clefts  and  cavities  of  the  primi- 
tive rocks,  by  the  concurrence  of  this  agent.  But  hitherto  we 
Iiave  acquired  very  little  knowledge  refpecbng  the  circumilances 
of  this  operation. 

Bergmann  obtained  rock  cryftals  by  diflblving  filex  in  the  flu- 
orick  acid,  and  fuiFering  it  to  evaporate  llowly.  I  left  on  the 
tables  of  my  cabinet  oF  mineralogy  a  receiver  and  a  retort,  in 
which  I  had  made  the  acid  of  fluor  ;  and  when  I  had  occafion, 
two  years  afterwards,  to  infpedl  this  apparatus,  I  found  the  re- 
ceiver almofl  entirely  corroded,  and  its  interiour  furface  lined 
with  a  fubtle  powder,  in  which  thoufands  of  rock  cryftals  might 
be  difcerned. 

Mr.  A  chard  informed  the  pub!  ick  that  he  had  obtained  rock, 
cryflals  by  caufing  water  impregnated  with  carbonick  acid  to 
filtrate  through  clay.  Mr.  Magellan  even  prefented  thefe  cryf- 
tals to  the  Academy  at  Paris  ;  but  the  experiment  though  re- 
peated with  the  greateft  care  by  feveral  chemifts  of  the  capital, 
was  not  attended  with  the  fame  refults. 

Since  that  epocha,  Mr.  De  Morveau,  having  inclofed  rock 
cryftals  with  a  bar  of  iron  in  a  bottle  filled  with  gafeous  water, 
perceived  a  vitreous  point  fixed  to  the  iron,  which  he  fuppofed 


ia^a  Earthy  Mixtures.      CryHahl 

to  be  a  rock  cryflal  formed  by  this  operation  ;  fo  that  he  t6^:=^ 
fiders  iron  as  a  nccefTary  intermedium  to  enable  the  carboniclc 
^cid  to  diffblve  quartz.  This  confequence  of  Mr.  De  Morveaa 
appears  to  agree  with  many  facls  which  have  been  colle6led 
concerning  the  formation  of  rock  cryftal.  We  fee  it  formed  m 
ochreous  earths  ;  and  I  poflefs  ochres  in  my  collection  which 
poflefs  many  of  thefe  fmall  two-pointed  cryftals. 

It  appears  to  me  that  it  is  not  neceflary  to  feek  for  a  folvenfc 
for  filex,  in  order  to  explain  the  formation  of  rock  cryftal.  The 
iimpie  divifion  of  this  earth  appears  to  me  to  be  fufTicient  for 
the  purpofe  :  and  I  could  bring  numerous  fa6ls  to  fupport  thi^ 
aflertion. — See  the  article  Cryilallization. 

It  is  proved  by  the  obfervations  and  experiments  of  Mr.  Genf- 
fane,  that  a  quartzofe  gurh  is  formed  by  fimple  tranfudatioft 
upon  rocks  of  this  nature  ;  and  the  fame  naturalill  has  takeii 
notice  that,  when  the  gurh  is  worn  and  depofited  by  water, 
Tock-cryftals  are  formed.  The  waters  which  work  their  way 
through  the  quartzofe  rocks  of  the  mine  of  Chamillat,  near 
Planche  les  Mines  in  Franche-compte,  form  quartzofe  ftalac- 
tites  to  the  roof  of  the  works,  and  even  upon  wood.  The  ex- 
tremities of  thefe  {lala£lites  which  have  not  yet  affiamed  a  foHd 
confiftetice,  are  of  a  granulated  and  cryftalUne  fubftance  eafiljr 
cruflied  between  the  lingers. 

In  thefe  cavities,  called  craques  by  the  miners,  a  fluid  gurh  is 
often  found,  and  ftill  oftencr  cryftals  ready  formed.  I  have  feen 
at  Saint  Sauveur,  in  the  work  of  La  Boilfiere,  near  Bramebiaou, 
feveral  incruflations  of  gurh  on  the  fides  of  the  gallery  ;  and 
thefe  fpreading  incruftations  were  terminated  by  well-formed 
cryftals,  wherever  the  wall  overhung  or  deviated  from  the  per- 
pendicular. This  gurh,  when  handled,  and  minutely  examin* 
ed,  had  no  other  appearance  than  that  of  a  filiceous  pafte  of 
confiderable  purity. 

The  fame  efFe6ls  appear  to  take  place  with  regard  to  rock 
cryftals,  as  with  the  calcareous  fpars.  They  are  formed  whenever 
their^principles,  in  a  ftate  of  extreme  divifion  and  attenuation, 
arc  fufpended  by  water,  and  depofited  with  all  the  circumftan- 
ces  which  nature  requires  in  order  that  cryftallization  may  take 
place.  I  do  not  even  think  it  neceftary  to  recur  to  the  property 
which  water  poflefles  of  fenfibly  diflblving  filex,  to  explain  the 
formation  of  thefe  cryftals  :  and  we  fhall  refer  the  formation  of 
quartzofe  ftala^lites,  agates,  &c.  to  the  fame  caufe. 

Rock  cryftal  is  frequently  coloured  by  iron,  in  which  cafe  it 
aflumes  peculiar  fliadss  which  have  been  denoted  under  differ- 
ent names.     We  fhall  place  them  here  as  fimple  varieties. 


Earthy  Mixtures,     Cr^als,  233 


VARIETY       I. 
Red  Cryftal— Fai,se  Ruby. 


It  is  frequently  mixed  with  different  (hades.  Its  colour  is 
deftroyed  by  fire,  according  to  Mr.  D'Arcet.  It  is  found  in 
Ba(bar<>,  in  Silefia,  in  Bohemia,  &c. 

When  it  is  of  a  dull  red,  it  is  called  the  Hyacinth  of  Com- 
poftella. 


VARIETY     II. 

Yellow  Cryftal— Bohemian  Topaz. 

It  has  fometimes  a  tin^e   inclining  to  yellow ;  its  colour  i^ 
ften  internal  only.     It  is  found  in  Velay,  near  Briftol  in  Eng- 
land, &c. 

VARIETY  ill. 
Brown  Cryftal—SMOKY  Topaz. 

This  brown  tinge  varies  froni  a  light  brown  to  a  deep  black. 
It  is  affirmed  that  they  may  be  rendered  clear  by  boiling  thenl 
in  tallow. — See  Journal  de  Phyfique,  t.  vii.  p.  360. 

It  is  found  in  Switzerland,  in  Bohemia j  in  Dauphiny,  &c. 

VARIETY  iV". 

Green  Cryftal False  EmeiCald. 

This  is  the  mofl  fcarce  and  the  moft  precious  of  coloured 
Cryftals.     It  found  in  Saxony  and  Dauphiny. 


VARIETY    V. 

filiie  Cryftal— Water  Sapphire. 

It  does  not  appear  to  differ  from  the  true  fapphire,  excepting 
in  being  lefs  hard.     I  have  feen  a  fpecimen  which  had  this  col- 
our,    it  is  found  in  Bohemia,  in  Silefia,  and  at  Puy   in  Velay, 
•  hich  has  caufed  it  to  be  called  the  Sapphire  of  Puv. 
2.,.F 


234  Earthy  Mixtures,     ^artz. 


VARIETY      VI. 


violet  Cryflal— the  Amethyst. 


Its  colour  is  more  or  lefs  deep  •,  and  it  aflumfes  a  confiderabfe 
brilliancy  by  polifliing.  When  the  cryflal  is  only  half  colour- 
ed, it  is  called  Prime  de  Amethijle,  It  loofes  its  colour  by  a  ftrong 
fire,  according  to  Mr.  D'Arcet.  This  cryftal  is  found  of  fufli- 
cient  magnitude  to  form  columns  of  more  than  one  foot  in 
height,  and   fever?!  inches  in'diameter. 


PivisioN    ir. 

Quartz. 

Thofe  fpeclmens  of  fijiceous  (lone  in  which  no  regular  form 
appears,  and  which  we  here  comprehend  under  the  name  of 
Qu^artZj  poflefs  various  degrees  of  tranfparency. 

Its  colour  diiTers  prodigioufly  ;  and  it  may  be  diflinguiflied 
kito  varieties  and  {lu'.lcs  perhaps  more  numerous  than  in  rock 
crydal  itfelf. 

It  feldom  forms  cn{'s^  mountains,  but  almofl  always  inter- 
fe£ls,  by  veins  more  or  Icfs  wide,  the  mountains  of  primitive 
fchiflus.  At  all  events,  t  have  made  this  obfervation  in  every 
mountain  of  this  kind  which  I  have  examined. 

The  blocks  of  quartz,  detached  by  waters,  are  rolled,  rounded, 
and  (Jepofited  in  the  forai  of  large  fbones  on  the  banks  of  rivers. 
The  fame  ftones,  mo?e  attenuated,  form  the  quartzofe  pebbles ; 
and  tliefe,  ftill  more  divided,  produce  fand. 

This  (lone  is  very  refradlory.  It  is  ufed  as  the"  bafis  of 
bricks  employed  in  the  conflru^lion  of  glafs  furnaces.  For  this 
purpofe  it  is  calcined  to  whitenefs,  and  in  that  flate  thrown  in- 
to v^ater.  By  this  means  it  may  be  eafdy  reduced  to'  powder, 
and  difpofed  to  form  a  combination  with  clay. 

Quartz,  well  pounded,  and  ufed  in  the  compofition  of  bricks, 
does  not  equally  refill  the  impreffion  of  fire,  if  the  precaution  of 
calcining  it,  and  extinguilliing  it  in  water  has  not  been  taken. 
I  have  obtained  a  proof  of  this  fadl,  by  emploving  the  fame^ 
kind  of  quartz  in  both  ways. 

This  fand  forms  an  excellent  mortar  with  good  lime  ;  and^ 
■when^  fufed  with  alkalis,  it  produces  a  very  beautiful  glafe. 


Earthy  Mipitures,     Flints.  235 

SPECIES     III. 

Silex,  Alumine,  Lime,  and  Iron,  intimately  mixed. 


^^^V      Si 

^^^The  ftate  of  finencfs  in  the  conftitueijit  principles,  and  t?heir 
'  jSnore  or  lefs  intimate  mixture  or  amalgamation,  appear  to  us  to 
!    reftablifh  two  divifions  among  the  (tones  of  this  fpecies.    We  (hall 

accordingly  di(lingui(h  them  into  ,coarfer  flints  and  (iner  flints. 

The  fir  ft  form  gun  flints,  petrofilex,  &c.  5    the  fecond  compre-* 

head  agates,  calcedonies,  &c. 

DIVISION      1. 

The  Coarfer  Flints. 

In  this  place  we  ihall  arrange  two  ftones  which  appear  to  dif- 
fer only  by  a  more  or  lefs  evident  degree  of  tranfparency.  The 
filex,  or  flint  properly  fo  called,  is  fcmi-tranfparent,  when  very 
thin,  as  for  example  at  its  edges :  the  petrofiiex  has  a  more 
opaque  colour. 

1.  Gun  Flint.— -The  gun  flint  gives  fire  with  fteel :  its  col- 
our is  ufually  brown  ;  and  its  furface  very  fre<juently  exhibits 
a  whiter  colour  than  the  middle,  and  lefs  hard  than  the  nucleus 
of  the  (lone.  This  external  part  (ticks  to  the  tongue,  and  indi- 
cates a  commencement  of  decompofition. 

The  abbe  Bacheley  has  a(rerted  that  marine  produftions,^fuch 
as  polipiers,  (liells,  &c,  are  capable  of  pafling  to  the  ftate  of  gua 
flint. — Journal  de  Phyfique,  Supplement,  1782,  t.  xxv. 

The  fpecifick  gravity  of  gun  flint  is  from  2.65  to  2.7.  This 
ftone  does  not  melt  in  tlie  fire  5  but  it  becomes  white  and  brittle 
by  repeated  calcinations. 

The  common  brown  filex  aflx)rded  by  analyfis  to  Mr.  Wieg- 
leb,  per  quintal,  eighty  filex,  eighteen  alumine,  and  two  iron. 

2.  Petrofiiex. — ^The  colour  of  petrofiiex  is  a  deep  blue,  or  a 
yellowilh  grey.  It  is  interfperfed  in  veins  through  rocks  ;  and 
from  this  circumftance  it  derives  its  name. 

Its  fpecifick  gravity  is  from  2.59  to  2.7. 

It  becomes  white  in  the  fire  like  gun  flint ;  but  it  is  more  fu- 
fible,  for  it  flows  without  addition.  Soda  does  not  totally  dif- 
folve  it  in  the  dry  way  ;  but  the  borate  of  foda,  and  the  phof- 
phates  of  urine,  diiTolve  it  without  effervefcence. 

Mr.  Kirwan  obtained  from  a  petrofiiex,  ufed  in  the  manufac- 
ture of  porcelain  by  Mr.  Lauraguais,  feventy-two  parts  filex, 
twenty-two  z^lumine,  j^nd  fix  Ume,  in  the  (quintal. 


%2^  Earthy  Mixtures,     Flint^s, 


DIVISION       II, 

The  Finer  Flints. 

This  divifion  exhibits  feveral  ftonc;,  which,  thonga  diftjii-. 
guiftied  by  names  and  a  different  value,  are  neverthelefs  onlj'- 
varieties  of  each  other.  We  fhall  content  ourfelves  with  enu- 
inerating  the  chief. 

1.  Agate. — This  is  a  femi-tranfparent  filex  of  a  very  fine 
body.  Its  texture  is  vitreous;  and  its  hard nefs  fuch  that  it 
refifts  the  file,  gives  fire  with  the  fteel,  and  takes  the  mod  beau- 
tiful polifh. 

The  agate  when  cxpofed  to  the  fire,  lofes  its  colour,  becomes 
opaque,  and  does  not  melt.       '  ' 

The  varieties  of  agates  are  infinite.  They  are  founded  on  the 
colour ;  and  they  are  diflinguifhed  into  clquded,  pundluar^d, 
fpotted,  irifed,  herborized,  nloiTy,  &c.  See  Daubenton. — The 
tiame  of  Onyx  is  given  to  that  kind  of  agate  which  is  formed  by 
concentrick  bands.  Mr.  Daubenton  has  proved  that  the  agate 
which  has  received  the  name  of  mofly,  is  really  coloured  by 
fmall  mofly  vegetation. 

The  pureft  agate  is  white,  tranfparent,  and  nebulous.  Sue! 
is  the  oriental  agate,  which  befides  appears  as  \l  it  had  protu- 
berances or  knobs  on  its  furfaces. 

Its  fpccifick  gravity  is  2.64.  I  confider  the  agates,  and  the 
other  flints  concerning  which  we  (hall  proceed  to  treat,  as  quart- 
!2ofe  ftaladites.  The  fides  of  geodes  which  are  agatized,  and  the 
ftrata  of  thofe  flints  which  are  found  in  places  where  infiltra- 
tions produce  rock  cryftals,  appear  to  me  conclufive  in  favour 
of  this  do£trine.  The  agates  have  the  fame  relation  to  quartz 
as  the  alabafters  to  calcareous  (tones,  and  tl^e  theory  of  their 
formation  is  the  fame.  Mr.  Dortheshas  exhibited  many  proofs 
of  this  theory  refpeQing  the  formation  of  thefe  (tones. 

2.  The  Opal»— •The  fdmi-tranfparent  agate  of  a  milky  white- 
nefs,  which  ex^iibits  a  glittering,  changeable,  internal  colour  o£ 
ti  blue,  red,  and  green  tinge,  is  known  by  the  name  of  Opal. 
That  which  comes  from  Hungary  has  a  kind  of  greyifh  clay  for 
ks  gangue.  The  moft  beautiful  opal  is  the  oriental  opal ;  fome- 
times  called  the  fpangled  opal,  becaufe  its  colours  appear  like 
equal  fpots  diftributed  over  its  whole  furface.  Thefe  opals  have 
received  various  names,  according  to  the  colours  they  reflect. 

The  chatoyant  Itones,  or  fuch  as  vary  their  colour  according 
to  the  pofition  of  the  light,  arid  the  eye  of  the  obferver,  are  vari- 
eties of  the  opal.  Such  are  the  girafol,  the  cat's  cy:,  the  Fini*> 
eye. 


Eartly  Alixti^res.     Flints,  23 1 

I  The  reflected  rays  of  the  girafol  are  weak,  bluifli,  and  mixed 
vithan  orange  yellow.  This  itone  has  been  found  in  the  lead 
nines  of  Chatelaudren  in  Britanny.  The  moft  obvious  char- 
icier  of  the  girafol  is,  that  it  exhibits  in  its  internal  part  a  lumi- 
ious  point ;  and  reliecls  the  rays  of  the  light  in  whatever  pofi- 
ion  it  may  be  turned,  when  it  is  cut  into  a  globe  or  hcmif- 
phere.  The  cat's  eye  has  a  ppint  near  the  middle,  from  which 
Proceed,  in  a  circle,  grecni  ih  traces  of  a  very  hvely  colour. 
The  moil  beautiful  Hones  of  this  kind  are  of  a  grey  and  mort- 
dore  colour.     They  come  from  Egypt  and  Arabia. 

The  fifties  eye  does  not  diifcr  From  the  cat's  eye  excepting  ia 
its  colour,  which  is  bluilh  :  it:  is  found  at  Java. 

3.  Calcedony. — The  calcedony  is  a  femi-tranfparent  agatp 
of  a  milky  whitenefs,  differing  from  the  foregoing  in  not  pof- 
fefling  the  chatoyant  property,  or.changeablenefs  of  colour. 

It  has  been  found  in  the  mines  of  Cornwall,  in  ftaladites  of 
lingular  elegance.  T|icfe  cvdcedonies  are  almoft  always  covered 
with  protuberances  Hke  the  ft ahig mites. 

The  protuberances  appear  to  be  formed  by  the  fuccelhve  ap- 
portion of  feverai  ftrata  or  coatings. 

~  In  Monte  Berico,  in  the  territory  of  Vicenza,  geodes  of  cal- 
cedony are  found  which  inclofe  water.  They  arc  called  En- 
nydria. 

I  pofTefs  in  the  Mineralo^Ical  Cabinet  of  the  povince,  calcedo- 
nies  of  Auvergne,  which  appear  to  be  chrydaHized  like  rock- 
cryltal.  The  cryftals  have  all  the  fat  and  un«^uous  appear- 
ance of  the  fame  balls  which  are  difperfed  on  the  rock  ;  but 
when  they  are  broke,  it  is  feen  that  the  appearance  arofe  from 
covering  of  calcedony  over  the  cryftal  of  quartz. 

Mr.  Bindheim  analyfed  calcedony,  and  fotmd,  in  the  centen- 
ary, 83.3  filex,  II  lime,  1.6  alumine,  and  a  fmali  quantity  of 
;ron. — Schriit,  Natur/For.  Free.  t.  iii.  p.  429. 

Mr.  Darcet  did  not  fucceed  i^i  fufmg  Calcedony,  but  it  lofl: 
its  colour. 

Calcedony  has  often  a  fhacle  of  blue,  yellow,  or  red. 

Mr.  De  Carozy  and    Mr.  Macquart'   obferved  in  Pola^id  the 

transformation    of   gypfum   to   the    ftate    of   calcedony. — See 

^he  Effai  de  Minsralogie  par    M.    Macquart  premier   memoire. 

Cacholong.     The  white  and  opaque  calcedony  is    known  by 

the  name  of  Cacholong.     Its  texture    refemble's    that  of  quartz, 

and  it  becomes  whiire    in  the  fire.     This  ftone  is    capable  of   a 

fine  polifli.     It  is  found  on  the  banks  of  a  river  named  Cach, 

■  near  the  Kalniouks  of  Bucharia,  in  whofe  language  the  wor4 


238  Earthy   Mixtures.      J  a/per. 

An  imaginary  value  has  been  given  to  a  modification  of  tJis 
cacholong,  which  has  the  property  of  becoming  tranfparent 
after  having  been  plunged  in  w^ater.  This  is  called  Hydro- 
phanes,  Lapis  Mutabilis,  Oculus  Mundi.  Mr.  Dantz  brought 
hydrophanes  to  Paris,  which  became  tranfparent  when  plunged 
in  water. 

Mr.  Gerhard,  on  the  28th  of  Auggft,  1777,  read  to  the  Acad- 
emy of  Berlin,  Obfervations  on  the  Hydrophanes.  He  found 
that  this  flone  contained  two  thirds  of  clay,  and  one  third  of  fi- 
Jex.  This  celebrated  naturalift  affirms  that' the  hydrophanes  was 
known  to  Beyle,  who  faw  one  of  them,  about  the  fize  of  a  pea, 
fold  in  London  for  two  hundred  pounds  iterling. 

The  hydrophanes  is  fufible  in  the  fire.  Soda  diffolves  it  with 
cfFervefcence  •,  the  borate  of  foda,  and  the  phofphates  of  urine, 
■without  cfFervefcence. 

5.  Carnelian.  Sardonyx.  The  carnelian  is  a  fpecies  of  agate, 
iiearly  tranfparent.  It  is  called  Carneole  when  it  has  the  col- 
our of  fleCh.  Its  hardnefs  varies  prodigioufly:  Thofe  which  are 
■white  or  yellowifh  are  not  fufhciently  hard  to  give  fire  with  the 
fteel.  When  ignited  it  lofes  its  colour,  and  becomes  opaque. 
The  moll  beautiful  fpecimens  refemble  the  garnet.  Its  fpecitick 
gravity  is  from  2.6  to  2.7. 

The  fardonyx  is  a  femi-tranfparent  filex,  of  an  orange  colour^ 
more  or  lefs  deep.  It  is  knobbed  like  the  calcedony  -,  and  pof- 
ieffes  the  hardnefs  and  fpecifick  gravity  of  that  flone.  Its  habi- 
tude in  the  fire  refembles  that  of  the  agate.  In  the  Royal 
Wardrobe  of  France  there  are  vefTels  of  fardonyx,  of  an  afton- 
ifliing  magnitude  and  beauty.  The  famous  raurrhine  vafes  were 
of  Sardonyx.     Sage,  t.  ii.  p.  163. 

SPECIES      IV. 

Silex,  Alumine,  and  Iron. 

Jafper  is  one  of  the  hardefl  (lones  we  are  acquainted  with. 
It  is  fufceptible  of  the  fineft  polifli  ;  and  its  colour  varies  pror 
digioufly,  which  has  occafioned  it  to  receive  the  names  of  San-- 
guine  Jafper,  Green  Jafper,  Flowered  Jafper,  &c. 

Mr.  Wedgwood  aflured  Mr.  Kirwan  that  Jafper  hardens  in  the 
fire  without  melting  ;  and  Mr.  Lavoifier  could  not  obtain  a  per- 
fe6l  fufion  by  the  afliftance  of  oxigenous  gas.  The  furface  only 
becomes-  vitreous. 

Mr.  Gerhard  afTerts  that  fome  fpecies  are  fufible  ;  and  Mr. 
Kirwan  attributes  this  property  to  the  mixture  of  lime  and  iron 
"wliich  produces  the  fulion. 


Earthy  Mixtures,     tourmaline.  i^gi 

Its  exc^ffive  hardnefs  has  induced  the  favages  of  Canada  to  a- 
tail  themfelves  of  it  in  the  fabrication  of  the  heads  of  javelins. 

Mr.  Dorthes  has  found  among  the  worn  flones  of  the  Medi- 
terranean (hore,  javeHn-heads  of  porphyry,  jafper,  horn  Hone, 
fchorl,  variolite,  &c.  probably  fabricated  by  the  ancient  inhabi- 
tants, the  Gauls. 

Thefe  javelin-heads  are  commonly  known  by  the  name  of 
Th under- Itones,  aad  are  diftinguilhed  by  lithologifts  by  the 
name  of  Ceraunites. 

SPECIES      V. 
Silex,  Aluminey  Lime  with  a  Cnall  portion  of  Magnefia,  and  Iron. 

This  fpecies  comprehends  all  the  fchorls  ;  and  mod  of  the 
volcanick  produ(f^s.  As  the  totirmaline  is  evidently  nothing 
more  than  a  variety  of  the  fchorl,  we  iliall  place  it  here,  though 
analyfis  has  not  difcovered  an  atom  of  magnefia  in  it,  and  the 
nature  of  its  principles  confounds  it  with  precious  Itones* 
Moreover  by  placing  it  between  thefe  and  the  fchorls,  it  poffef- 
fes  a  fituation  affigned  to  it,  as  well  by  its  natural  chara6ters  as 
by  its  conftltuent  principles. 

I.  The  Tourmaline.  This  (lone  poflcffes  the  tranfaparency 
of  the  fchorl.  Its  appearance  and  fraclure  are  vitreous,  its  tex- 
ture lamellated,  its  hardnefs  fo  confiderable  as  to  cut  glafs. 
When  heated  to  the  two  hundredth  degree  of  Fahrenheit,  it  be- 
comes electrical  :  a  ftronger  fire  deprives  it  of  this  property. 
It  is  fufible  by  the  blow-pipe,  with  ebullition  :  the  pure  tourma- 
line was  melted  into  a  black  glafs,  in  the  experiments  of  Mr. 
Lavoifier. 

Tourmalines  have  been  found  in  the  ifland  of  Ceylon,  in 
Tyrol,  and  in  Spain. 

Its  form  is  that  of  a  nine-fided  prifm,  terminated  by  two  flat 
trihedral  pyramids.  Mr.  De  Joubert  pofleiles  one  whofe  prifm  is 
feven  inches  and  a  half  loni^,  and  eleven  inches  in  circumference. 

The  prifmatick  tourmaline  has  no  eledlrick  effect  but  accord- 
ing to  the  direftion  of  its  column  :  the  fphere  of  activity  of  the 
SpaniQi  tourmaline  is  more  extenfivc  than  that  of  Tyrol. 

The  valuable  refeai;ches  of  Bergmann  upon  this  ftone  may 
be  confulted  in  his  dilTcrtation  concerning  its  analyfis.  Mr. 
Tofani  has  annexed  a  fet  of  interefling  notes  to  his  tranilation  of 
this  work. 

The  rcfults  of  Bergmann's  analyfis  exhibits  its  component 
parts  in  the  following  proportion  : 

1.  The  tourmaline  of  Tyrol  contains   alumine  forty-two,  fi- 
kx  fortv,  lime  twelve,  iron  fix. 


240  Earthy  •  Mixtures.      Sckortfi 

2.  The  tourmaline  of  Ceylon,  alumine  thirty-nine,  filex  thir'=» 
ty-feven,  lime  fifteen,  iron  nine. 

3.  The  tourmaline  of  Brazil,  alumine  fifty,  filex  thirty-four, 
lime  eleven,  iroa  five. 

The  fpecifick  gravity  of  the  tourmaline  of  Ceylon  is  30.541^ 
that  of  Spain  and  of  Tyrol  is  30.863,  water  being  10.000. — 
See  Brifibn. 

II.  Schorl.  The  di{lin£l  properties  of  fchorl  are,  an  appear- 
ance of  femi-vitriiication,  fufibility  in  a  moderate  fire,  ar.d 
hardnefs  approaching  to  that  of  cryllal. 

There  are  few  ftones  w|iich  exhibit  a  greater  variety  of  form 
or  colour. 

They  enter  into  the  compofitioh  of  porphyry,  of  ferpen:tine,' 
of  granite,  and  are  very  frequently  found  with  the  magnefian 
ftones. 

We  {hall  diflinguifh  the  fchorls  into  cryftallized  and  irregular- 
ly (haped   fchorls. 

A.  All  the  varieties  which  depend  upon  colour  may  be  re- 
duced to  four 

1.  Black  Schorl.— The  black  fchorl  is  found  chiefly  in  gran- 
ites. It  has  almoit  always  the  form  of  prifms  more  or  lefs  per- 
fect. The  number  of  fides  of  thefe  prifms  is  various  ;  they 
are  fometimes  grooved  ;  they  fometimes  terminate  in  trihedral 
obtufe  pyramids,  placed  in  contrary  diredlions  ;  in  fome  places 
they  are  found  feveral  inches  long,  and  the  union  of  thefe 
prilms  frequently  forms  grcu pes  of  feveral  in  diameter.  Their 
black  colour  is  more  or  lefs  deep.  When  urged  by  fire,  they 
become  refolved  into  a  bbck  uniform  gUfs  of  an  imperfect 
fluidity  like  palle. 

The  analyfis  of  the  black  prifmatick  fchorls  of  Gcvaudan  af- 
forded me,  per  quintal,  fifty-two  filex,  thirty-feven  alumine,- 
five  lime,  three  magnefia,  and  three  iron. 

2.  Green  Schorl. — ^This  variety  exhibits  the  fame  form,  and 
the  fame  modifications  ;  but  the  mod  common  of  its  cryflialli- 
zations  is  that  of  a  tetrahedral  prifm,  terminating  in  fhoit 
pyramids  likewife  tetrahedral. 

3.  Violet  Schorl.  This  variety  was  dlfcovered  in  1 781  by 
Mr.  Schreiber,  below  the  grotto  of  Aunts  •,  fituated  at  the  dif- 
tance  of  one  league  from  Bourg  IVoifan  in  Dauphiny.  Mr.  De 
la  Peyroufe  likev/ife  found  it  at  the  Peak  of  Dretliz,  in  the  Py- 
yenean  Mountains. 

This  fchorl  poflefTes  a  certain  degree  of  tranfparency.  It  iJ; 
cryftallized  in  rhomboids  ;  its  texture  is  lamellated  ;  two  oi^ 
tiie  rhomboidal  planes  of  each  pyramid  have  their  faces  flriated 
parallel  to  each  orher. 


jEarth^  Mixtures,     Volcantch  ProduBs.  24 1 

Schorl  lofes  its  colour  in  the  fire,  and  one  thirteenth  of  its 
Weight  ;  it  becomes  of  a  greyifh  white  j  and  with  a  ftionget 
degree  of  heat  it  fwells  up,  fubfides,  and  forms  a  black  enamel. 

Its  fpecifick  gravity  is  32.956  according  to  Brifibn. 

4.  White  Scorhl.— This  variety  has  been  found  in  the  moun- 
tains of  Corfica,  Dauphiny,  and  the  Pyrenees.  It  is  of  an  opaque 
white  colour,  and  vitreous  appearance  ;  and  is  found  in  cryftals 
on  the  furface  of  certain  ftones  of  the  nature  of  the  lapis  olla- 
ris.  I  have  feen  a  layer  of  this  fchorl  between  amianthus  anti 
the  lapis  oUaris.     It  melts  in  the  fire  into  a  white  enamel. 

The  aualyfis  of  this  fchorl  from  the  Pyrenean  Mountains  af- 
forded me, per  quintal,  fifty-five  parts  filex,  twenty-two  alumine, 
thirteen  magnefia,  and  feven  lime. 

B.  The  fchorl  in  connected  mafTes  nearly  approaches  the 
jafper  in  its  external  charadters.  It  may  be  diftinguiihed  how* 
ever  by  its  fracture,  which  is  of  a  drier  grain,  and  exhibits  a 
difpofition  to  cryftallization.  This  ftone  ferves  as  the  bafis  to 
feveral  porphyries.  The  variolite  of  Durance,  a  ftone  fingu- 
lar  on  account  of  the  fuperftitions  to  which  it  has  given  rife,  is 
a  fchorl  in  the  mafs,  covered  with  grains  of  the  fame  nature  as 
the  ground,  but  of  a  clearer  green. 

Mr.  Dorthes  has  obferved  variolites  on  the  coaft  of  oiir  Me- 
diterranean fea  ;  and  affirms  that  this  ftone  in  its  decompofition 
undergoes  changes  of  colour  which  fucceed  each  other  in  the 
order  of  the  folar  fpedlrum. 

III.  Volcanick  produfts. — ^The  principal  produfts  of  volca- 
noes are  bafaltes,  lava,  and  terra  pozzolana.  Thefe  fubftances 
are  abfolutely  of  the  fame  nature  •,  but  they  are  principally  dif- 
tinguiflied  by  the  name  of  Bafaltes  when  their  form  is  regular. 
When  they  have  no  determinate  figure,  they  are  denominated 
Lavas  ;  and  when  confiderably  attenuated  they  are  diftinguifti- 
ed  by  the  name  of  Terra  Pozzolana. 

Bafaltes  is  diftinguiflied  into  the  prifmatick  bafaltes  with  a 
number  of  fides  from  three  to  feven  ;  the  bafaltes  in  tables  and 
the  fpherical  bafaltes. 

Lava  is  diftinguiihed  into  compa£i  lava,  porous  lava,  twifted 
lava,  lava  in  tearj^,  &c. 

Several  naturalifts  have  clafied  the  bafaltes  with  the  fchorls, 
and  feme  of  them  have  afligncd  the  fame  origin  to  both.  It 
appears  neverthelefs  to  be  generally  agreed  that  bafaltes  is  a 
product  of  fire. 

It  fometimes  differs  from  fchorls  in  its  chemical  analyfis,  and 
alfo  in  the  circuraftance  of  its  not  always  affording  magnefian 
«anh. 


24  ^  Earthy  Mixtures,     Lavas. 

The  colour  of  bafaltes  is  of  a   deep  green,    almofl  conftantly^ 
covered  or  enveloped  with  a   ferruginous  cruft   lefs    black  thai 
the  internal  part.     The  iron  is  in  the  ftate  of  ochre. 

Its  form  is  conftantly  prifmatick,  which  is  the  natural  effedfcT 
of  the  contrafiion  which  it  fuffers  in  cooling. 

Bafaltes  is  converted  by  £te  into  a  moft  beautiful  black  glafs. 
This  property,  which  is  admitted  by  every  ch^mift,  induced  tnc 
to  fufe  it,  and  blow  it  into  bottles. 

The  attempt  was  perfectly  fuccefsful  at  the  glafs-houfe  df ' 
Mr.  Gilley  of  Ailais,  and  at  that  of  Mr.  Giral  of  Erepian.  I 
ilill  preferve  the  firft  veflels  which  were  blown  of  this  fubflance  i 
they  arfe  the  moft  beautiful  black,  aftonifhingly  light,  but  without 
tranfp?vrency.  Encouraged  by  this  firft  fuccefs,  I  requefted  Mr. 
Caftelveil,  the  proprietor  of  another  glafs-houfe,  to  undertake 
fome  expetiments  ;  and  in  confequence  of  various  trials  we  fuc- 
ceeded  in  fabricating  bottles  of  an  oli-ve  green,  in  which  the 
moft  extreme  lightnefs,  and  a  truly  aftoniftiing  degree  of  folid- 
ity.  were  united.  Pounded  bafaltes^  foda,  and  fand,  in  nearly  equal 
proportions,  formed  their  compofition.  The  properties  of  thefe 
bottles,  as  proved  by  my  own  experiments,  as  well  as  by  thofe 
which  Mr.  Joly  De  Flcury,  at  that  time  comptroller-general,  or- 
dered to  be  made,  render  them  of  the  greateft  value  in  com- 
merce 5  and  Mir.  Caftelveil  was  unable  to  fupply  the  numerous 
orders  he  recclvfed.  This  manufacture  fupported  itfelf  with 
fuccefs  for  two  years;  but  at  the  end  of  that  time  the  fuperi- 
ority  of  the  bottles  ceafed  to  be  the  i^me  j  the  munufaClurer 
received  the  reproaches  of  the  confumer  ;  this  fuperb  eftablifh- 
ment  gradually  fell  off,  and  was  at    length  abandoned. 

Since  that  period  I  have  made  r^\^eral  e2j:periments  in  the  large 
way,  from  which  I  have  obtained  refults  that  rhay  be  of  fcrvice 
to  fucli  as  are  defirou^  of  following  this  manufafture. 

1.  The  nature  of  the  combuftible  uled  in  glafs-houfes  has  a 
prodigious  ef?e£l  in  modifying  the  refults' of  experiments.  The 
lame  bafaltes  which  Mr.  Caftelveil  confideted  as  too  refradlory 
in  his  furnace  heated  by  wood,  wasTound  of  too  fufible  a  nature 
by  Mr.  Giral,  who  was  in  the  habit  of  ufi ng  pit-coal  in  his  glafs 
works.  The  former  manufa£lurer  accordingly  made  his  glafs 
by  adding  foda  to  the  lava,  whilft  the  latter  mixed  it  with  a 
very  refractory  fand. 

2.  The  fame  lava,  fufed  without  addition,  may  be  blown  in 
one  glafs-houfe  and  ndt  in  another.  This  irregularity  appeared 
to  me  at  firft  to  depend  effentially  on  the  fkill  of  the  workmen  ; 
but  I  have  been  fmce  convinced  that  it  is  totally  independent  of 
that  circumftance. 

In  a  furnace  which  is   ftrongly   heated,  the  fufed  lava  fome 
hincs  becomes  fiuid  like  water,   and  drops  from   the  iron  tubv- 


Earthy  'Mixtures,    'Lavas,  243 

as  foon  as  it  is  coljec/led.  The  fame  lava,  when  fufed  in  other 
:furnacfs,  will  preferve  a  fufficient  degree  of  confiitency  to  admir, 
of  being  blown.  I  am  myfelf  wellaiTured  that  the  lava  might  be 
be  wrought  in  any  glafs-houfe  whatever  provided  the  moment 
was  feized  in  which  the  parte  was  neither  too  fluid  nor  too 
thick  to  be  wrought  ;  but  thcfe  attentions  are  too  delicate,  and 
too  minute,  to  be  obferved  in  works.in  the  large  way. 

3.  The  hardefl:  bafaltes  aifords  the  moil:  beautiful  glafe 
•  "When  it  is  contaminated  with  foreign  principles,    fuch  as  the 

nodules  of  lime,  the  glafs  is  brittle,  and  has  not.a  fufHcient  con- 
nedtipn  of  its  p^rts.  This  circumltance,  in  my  opinion,  was  the 
caufe  of  the  bad  quahty  of  the  glafs,  which  produced  the  failure 
in  Mr.  Caftelveil's  manufactory. 

4.  I  have  feen  very  hard  bafaltes  interfperfcd  with  black  in- 
fufible  points,  infomuch  that  thefe  points  became  enveloped  in 
the  vitreous  pafte  without  any  perceptible  alteration.  The  vol- 
canick  mountain  of  Efcandorgue  near,Lodeve  afforded  me  this 
variety  of  bafaltes. 

In  the  article  Verrerie  of  the  Encyclopedic  Methodique,  ma-y 
be  feen  the  various  refults-  which  we  have  obtained  with  Mr. 
Allut,  in  feveral  experiments  made  in  common  in  the  royal  glafs 
works  of  Bof<^uet  and  elfewhere. 

I  ihall  conclu<:'e,  from  the  obfervatioii-which-iny  experiments 
:have  hitherto  afforded — 

1.  That  lava  may  be  ufed  as  a  fl'uxin  glafs-houfes  to  diminifti 
the  confumption  of  foda.  This  is  the  fi'ngle  purpofe  I  at  that 
time  propofed  to  myfelf,  and  I  have  cleariy  accompliflied  it, 
I.  By  the.  rei^'ults  of  experiments  which  have  ihewn  that  refrac- 
tory fand  becomes  fufed  in  the  glafs  furnace  by  a  mixture  of 
lava.  2.  By  the  eifedls obtained  in  all  the  works  in  the  large 
way,  in  which  the  addition  of  lava  permitted  a  diminution  in 
the  proportion  of  foda. 

2.  It  is  very  dit^cult  to  eflabliOi  a  rigorous  procefs,  applicable 
to  all  circumftances,  by  which  lava  may  be  wrought  without  ad- 
dition. My  bottles  into  which  the  lava  entered  as  a  component 
part,  were  fcarcejy  known,  before  it  was  publiflied  that  they 
were  formed  of  lava  without  addition  ;  nothing  more  being  faid 
to  be  required  than  to  fufe  the  lava  in  or^er  to  form  bottles. 
This  ftrange  report  affecled  me  very  little  in  the  principle ;  be- 
caufe  I  had  neither  fpoken,  written  nor  printed  any  thing  which 
was  capable  of  giving  authority  to  fuch  an  errour  ;    and  I  was 

.content  to  reply  to  ail  perfons  who  demanded  information,  by 
informing  them  that  experience  had  taught  me  that  an  addition 
of  lava  diminilhed  the  proportion  of  foda  in  the  compofition  of 
glafs,  and  that  this  new  principle  rendered  the  bottles  lighter  and 

.itrongef. 


244  Earthy  Mixtures,     Trapp.     Chryfoprafe. 

3.  That  the  only  advantage  which  can  be  derived  from  fufing 
lava  vi^ithout  addition,  is  to  pour  it  into  moulds,  to  form  paving 
Hones,  chimney  jams,  &c.  The  facility  with  which  it  is  fufed 
by  the  affiftance  of  pit-coal,  would  render  thefe  works  of  fmali 
expenfe  ;  and  it  might  eafily  be  decorated  by  incrufling  it  with 
metallick  colours. 

4.  That  the  difference  in  the  nature  of  volcanick  products 
produces  fuch  a  variety  in  the  refults  of  their  fufion,  that  I  con^ 
iider  it  as  impoffible  to  aflign  a  contlant  and  invariable  procefs, 
by  which  the  fame  refult  may  infallibly  be  obtained.  This  cir- 
cumftance  renders  it  neceffary  to  make  preliminary  trials  in  al! 
cafes  wherein  it  is  intended  to  ufe  bafaltes  in  the  fabrication  01 
bottles. 

The  bafaltes  has  been  confidered  as  fimilar  to  a  ftone  known 
by  the  name  of  Trapp  ;  it  refembles  it  in  feveral  ef|ential  prop- 
erties ;  the  colour,  form,  weight,  and  the  nature  of  the  compo- 
jient  parts  of  each,  appear  to  authorize  us  in  confounding  them 
together,  as  Pcrgmann  has  proved  by  the  fine  comparifon  he  has 
made  of  thefe  two  ftones,  in  his  analyfis  of  the  volcanick  pror 
«3u£ls  of  Iceland.  But  this  fame  chemift  has  ihewn  that  they  '■ 
differ  in  feveral  other  points  of  view. 

The  trapp  exhibits  no  chara£ler  which  can  give  ground  to  fuf- 
pe6l  that  its  origin  is  volcanick  ;  it  is  found  in  Sweden,  in  the 
primitive  mountains,  and  upon  (Irata  of  granite  and  fchiftus, 
and  fometimes  even  upon  banks  of  calcareous  (lone. 

The  trapp  of  the  mountains  of  Weftrogothland  is  ufually  in 
the  form  of  fquare  irregular  cubes  5  and  it  is  indebted  for  its 
denomination  to  this  refemblance  to  the  fteps  of  a  ftair  cafe.  It 
likewife  exhibits  the  form  of  a  triangular  prifm,  though  feldom  5, 
:and  fometimes  it  refembles  immenfe  columns. 

The  trapp  afforded  Bergmann  the  fame  principles,  and  nearly 
in  the  fame  proportion,  as  the  bafaltes.  The  difference  is  fcarcc- 
}y  the  hundredth  part ;  and  this  variation  is  frequently  found  n\ 
pieces  of  the  fame  bafalte^. 

SPECIES        VI. 
Silex,  Lime,  Magnefia,  Iron,  Copper,  and  the  Fluorick  Acid.  • 

This  combination  forms  the  chryfoprafe.  Its  colour  is  a  femi-i 
tranfparent  apple  green,  and  it  is  harder  than  the  fufible  fpars 
and  quartz  of  the  fame  colour. 

The  fire  deprives  it  of  its  green  colour,  renders  it  white  and 
opaque,  and  forms  by  the  affiilance  of  vital  air  a  compadl  angj 
ii^ilky  globule.— See  Erhmann. 


Eartb'j  Mixtures,     Feld  Spar,  24^ 

Mr.  Achard  obtained,  in  the  quintal  of  this  ftone,  95  parts 
filex,  1.7  lime,  i.%   magnefia,  0.6  copper. 

SPECIES      vn. 
Silex,  the  blue  Fluate  of  Lime,  with  the  Sulphate  of  Lime  and  Iron. 

This  fingular  combination  forms  the  Lapis  Lazuli,  or  Azure 
3tone. 

Its  colour  is  of  a  beautiful  opaque  blue,  which  it  preferves  in 
a  ftrong  heat,  and  does  not  fuffer  any  alteration  in  this  refpedl  by 
the  contaifl  of  air. 

The  powder  of  this  ftone  makes  a  flight  effervefcence  with 
acids :  but  after  calcination  it  forms  a  jelly  with  acids,  without 
exhibiting  any  previous  effervefcence. 

The  powder  of  this  ftone  forms  the  valuable  colour  known  by 
the  name  of  Ultramarine.  The  price  of  this  colour  is  propor- 
tioned to  its  intenfity  ;  and  its  value  is  accordingly  leaft  whea 
it  is  mixed  with  pyrites,  becaufe  thefe  bodies  diminifh  the  viva^ 
city  of  its  colour. 

This  ftone  affords  water  by  calcination,  and  when  diftilled 
with  the  muriate  of  ammoniack,  it  forms  martial  flowers  :  which 
proves,  according  to  Mr.  Sage,  that  its  colour  is  owing  to  iron. 

The  azure  ftone  is  fufed  by  a  ftrong  heat  into  a  whiriih  glafs  ; 
^nd  by  the  affiftance  of  oxigene  it  forms  a  white  tranfparent 
globule  inclining  to  green,  without  internal  bubbles,  and  not 
obedient  to  the  magnet. 

The  fpecifick  gravity  pf  the  lapis  lazuli  of  Siberia  is  29,454. 
See  Briffon. 

Plates  of  the  lapis  lazuli  may  be  feen  upon  almoft  all  richly 
decorated  altars  ;  it  is  likewife  made  into  toys. 

Margraff  obtained  from  this  ftone  calcareous  earth,  gypfum, 
iron,  and  filex.  Mr.  Rinmann  has  difcovered  that  it  contains 
;he  fluorick  acid. 

SPECIES       VIII. 

Silex,  Alumine,  Barytes,  and  Magnefia. 

This  ftone  is  known  by  the  names  of  Feld  Spar,  Rhomboidal 
Quartz,  Spathum  fcintillans,  Petuntze. 

it  very  frequently  forms  one  of  the  principles  of  granite,  and 
the  cryftals,  which  are  found  feparate,  arife  from  the  decompo- 
iition  of  this  primitive  rock. 

The  texture  of  feld  fpar  is  clofe,  lamellated,  and  it  is  lefs  hard 
^2x1  quart?. 


24^  E^f'i^y  J^^xturcs*     FeUl  %par» 

It  fufes  without  addition  into  a  wlxitifh  gJafs.  I  han'C^Rever- 
thclefs  obferved  a  very  great  variety  in  tlie  feld  fpars,  with  re- 
;gard  to  their  habitude  in  the  fire.  That  of  Avcnne,  which  is  ia 
the  form  of  whitifh  cry  Hals  mixed,  with  quartz,  afforded  me  a 
tranfparent  giafs  of  extreme  hirdnefs  by  the  fimple  addition  o/ 
■one. third  of  hme  :  whereas  that  of  Efper on,,  treated  in  the  fame 
manner,  did  not  exhibit  the  fmallefl:  fign  of  fufion. 

The  fpecifrck  gravity  of  white  feld  Ipar  is  25,9457 — SeeBrif» 
ion. 

Feld  fpar.  exhibits  feveral  varieHesin  itsform  and  colour. 

Mod  of  the  pieces  of  feld  fpar  inclofed  in  granite  have  a, 
-rhomboidal  form  ;  and  when  this  primitive  rock  becomes  decom- 
pofed,  the  cryftals  of  feld  fpar  are  detached,  and  remain  con- 
founded with  the  rubbifh.  The  granites  of  our  province,  almoit 
all  of  them,  contain  thefe  cryftals,  fome  of  which,  are.an  inch 
and  an  half  in  diameter, 

Feld  fpar  has  been  found  cryftallized  in  tetrahedral  prifms^ 
iterminating  in  pyramids   with  four  fides. 

Ipoilefs  fome  fpecimens  of  feld  fpar  of  Auvergne,  whofe  tet- 
xahedral  prifms  are  flattened  and  terminated  by;  a  dihedral  fuin- 
mit. 

The  princrpalfhadcs  of  coloiiT  in  feld  fpar  are  white,  rofe- 
•colour,  and  chatoyant,  or  of  changeable  colours, 

The  white  tranfparent  feld  fpar  is  very  rare  ,  there  is  a  piece 
in  the  Royal  Cabinet  of  the  Mineral  School,  .v/hich  comes  Jroni 
Mount  St.-  Gothar. 

One  hundred  parts  of  white  feld  fpar  contain  about  fixty-feven 
filex,  fourteen  alumine,  eleven  barytes,  and  eight  magnefia. 

The  rofe-coloured  feld  fpar  is  not  very  fcarce.  Our  moun- 
tains exhibit  much  of  it.  It  abounds  with  iron,  which  is  in  the 
ilate  of  ochre.  Some  experiments  have  fhewn  me  that  this  va- 
Tiety  is  more  fufible  than  the  others.  My  analyfes  have  even 
exhibited  a  larger  portion  of  magnefia*,  and  its  conrillence  ap- 
pears to  me  to  be  lefs  firm  than  that  of   other  fpecimens. 

Feld  fpar  is  compofed  of  rhomboidal  laminse,  which  give  it 
the  property  of  exhibiting  various  colours,  in  a  greater  or  lef^ 
degree.  Large  pieces, of  fcjd  fpar  haye.  been  found  on  the  north- 
ern coaft  of  Labrador,  worn  down  by  the  waters  into  a  round 
form/  of^abluifli  grey.,colour,  apd  e-xliibiting  tl>e  moll  agreeable 
change  of  colours,  according:  tO;  the  varia.tion  of-pofition.  1  he. 
colouraare  a  beautifulceleftialiblue,  (haded  withjgreen.  Thi? 
flone.  is.known;by ;th$  name.of  Labrador  Stone.  Granites  are? 
frequently  found,  in  which  the  feld  fpajC;  exhibits  its  changeabi© 
coleurs.wiihwtbeing.wrought*: 


'  Itafihy  M'Mttires,     Stofjcr,  ^^ff 


CLASS       III. 

foScerning  the  Mixtures  of  Stones  among  each  other.    Stony  Mixtures,- 

Rocks. 


^^Kohcernini 

W 

^^  The  mixture  of  the  primitive  earths  with  each  dthter  form  the 
ftones  we  havie  hitlierto  tteateii  of ;  and  thefe  (loties,  united  anct 
conne6led  together,  or  as  it  were  joined  by  a  cement,  coiiftitute 
the  numerous  ciafs  of  peMes  or  ftoiies,  concerning  which  we 
fhall  proceed  to  treat.  It  is  evidently  fecrr  that  the  mixture  of 
various  (tones  has  been  produced,  either  by  revolutions  which 
have  reverfed  and  confounded  the  whole  furface  of  countries,  or 
by  the  ia£liwi  of  waters,  which  have  fuceefhvely  formed  the 
llrata  of  rounded  flints  fpread  over  the  furface  of  the  globe,  and 
have  afterwards  depofited  in  their  interftiees  that  earthy  matter 
which  has  connedled  them  together.  Thefe  mixtures  have  af- 
terwards acquired  a  degree  of  hardnefs  ;  and  at  length  appear- 
ed to  form  one  fingle  fubftance. 

We  fliali  eftablifii  our  genera  upon  the  prefence  of  fuch  flones 
as -predominate  ;  and  the  fpecies  will  be  deduced  from  the  vari- 
ety of  ftones  mixed  with  that  which  determines  the  genus. 

GENUS       I. 

Rocks  formed  by  the  mixture  of  Calcareous  Stones  with  other  Species. 

Though  the  bafis  of  calcareous  ftones  enters  into  the  compo- 
fitidn  bf  the  greater  part  of  lithoIoo:ick  fubftances,  we  find  few* 
vocks  which  can  be  ranged  in  this  clafs. 

SPECIES       I. 

Carbonate  of  Lime,  and  Sulphate  cf  Barytes. 

Mr.  Kirwan  obferved  compound  ftones  in  Derbyftjirc,  form- 
ed of  chalk  intermixed  with  nodulco  of  ponderous  fpar. 

SPliCIES        II. 

Carbonate  of  Lime  and  Mica. 

The  green  marble  of  Cipolin  of  Autun  is  of  this  kind.  It  is 
compofed  of  eighty-three  parts  carbonate  of  lime,  twelve  green: 
mica,  and  one  iron. — Journal  de  Phyfique,  t.  xii.  page  ^!^.  Cal- 
careous ftones  are  found  in  Italy,  which  exhibit  brilliant  fpecks 
cf  mica,  and  are  known  by  the  tidmc  of  Mafignc. 


248  Earthy  Mixtures,     Stortet, 

SPECIES     III. 

Mixtures  of  Calcareous  and  Magnefian  Stones. 

Sulphate  of  lime,  fluate  of  lime,  and  carbonate  of  liriie  arft 
found  mixed  with  (teatites,  ferpentine,  talc,  amianthus,  and  af- 
beitos.  Such  is,  for  example,  the  white  marble  interfperfed, 
with  fpots  of  {teatites,  and  defcribed  by  Cronftadt. 

SPECIES       IV. 

Calcareous  Stones,  and  Fragments  of  Quartz 

Quartz  is  fometimes  found  in  calcareous  cement.  Sweden 
and  Siberia  exhibit  feveral  marbles  which  give  fire  with  the  fteel. 
The  calcareous  grit,  fo  common  in  the  fouthern  part  of  our 
kingdom,  is  of  this  fpecies.  The  fand  is  compofed  of  fragments 
of  quartzofe  flints,  rounded  and  connecSled  by  a  calcareous  glu- 
ten or  cement.  By  digeftion  of  gritftone  in  an  acid,  the  calca- 
reous cement  becomes  diflblved,  and  the  proportion  which  the 
fand  bears  to  the  whole  may  then  be  eafily  determined. 

This  grit-ftone  is  feldom  hard  enough  to  be  ufed  in  building, 
or  in  paving. 

At  Nemours,  and  at  Fontainbleau,  this  (lone  has  been  found 
cryftallized  in  perfecft  rhomboids  :  the  cabinets  of  naturalifts 
are  enriched  with  fuperb  famples  of  this  kind. 

I.ime-ftone  has  likewife  been  found  ferving  as  a  cement  for 
feld  fpar,  fchorl,  &c.  *,  but  this  is  fomewhat  rare. 

Mr.  De  Saufiure  has  defcribed  a  ilone  whofe  elements  are 
quartz  and  fpar. 

Our  fhores  afford  pebbles  of  hard  marble  of  a  light  grey  col- 
our, interfperfed  with  feld  fpar  and  quartz. — See  Dorthes. 

GENUS       II. 

Compound  Stones  formed  by  the  Mixture  of  Barytick  Stones  with  other 

Stones. 

As  ponderous  fpar  is  of  confiderable  fcarclty,  and  is  almoft  al- 
ways found  alone,  this  genus  will  not  be  numerous. 

SPECIES      I. 

Ponderous  Spar  mixed  with  afmall  quantity  of  Calcareous  Spar. 

The  diocefcs  of  Alals  and  of  Uzes  afforded  me  this  fpeclcs  ;. 
?nd  I  have  myfelf  obferved  in  the  latter  rhomboids  of  calcareous 


Earthy  Mixtures,     Stones,  a^p 

fpar,  fo  well  mixed  with  the  laminae  of  ponderous  fpar,  that  it  is 
impofTible  to  feparate  them  without  deftroying  the  ftone.  It  was 
among  the  veins  of  ponderous  fpar  which  are  found  on  the  road 
from  Fortes  to  Alais,  that  I  faw  this  mixture. 

SPECIES      II. 

Ponderous  Spar  and  Serpentine. 

Mr   Kirwan   defcribes  a  fpecies  of  ferpentine  with  fpots  of 
barytes. 

SPECIES      III. 

Ponderous  Spar  and  Fluor  Spar. 

The  ponderous  fpar  of  Auvergne  is  mixed  with  fluor  fpar :  I 
have  many  fpecimens  of  this. 

SPECIES      IV. 

Ponderous  Spar  and  Indurated  Clay. 

This  is  the  Kros-ftein  of  the  Germans.  The  clay  which 
forms  the  ground  is  grey,  and  includes  a  ponderous  fpar  of  a 
white  colour,  which  is  difpofed  in  this  clay  in  the  form  of  veins, 
that  might  be  taken  at  firlt  fight  for  vermiculites,  or  in  general 
for  the  remains  of  fome  organized  fubftances.  This  ftone  is 
found  at  Bochnia  in  Poland. 

SPECIES      V. 

Poderous  Spar  and  Quartz. 

I  have  in  my  colle£lion  feveral  fpecimens,  in  which  the  pon- 
derous fpar  is  difpofed  in  ftars  upon  a  matrix  of  the  nature  of 
fdex. 

SPECIES  VI. 

Ponderous  Spar  and  Lava. 

The  extin£l  volcanoes  of  the  diocefe  of  Beziers  have  afforded 
me  lavas,  partly  decompofed,  whofe  furface  exhibits  radii  of  pon- 
derous fpar,  which,  at  firft  fight,  I  took  to  be  zeolite. 
2...H 


2^^  Earthy  Mixtures.     Stoties, 


GENUS  lit. 

Rocks  or  Stones  formed  by  the  Mixtur'e  of  Magnelian  Stones  with: 
other  Kinds. 


SPECIES  t, 

Magnefian  Stones  mixed  together. 

The  fame  rock  often  exhibits  the  various  known  magnefian 
ftones  in  conta£l  with  each  other.  Thus  we  fee  the  afbeftos  pla- 
ced befide  the  amianthus,  the  ferpentine  in  contadl  with  the  af* 
beftos,  the  fteatites  in  contact  with  talc. 

SPECIES  n. 

Magnefian  Stones  and  Calcareous  Stones. 

The  ferpentine  has  been  found  fpotted  with  calcareous  fpar^ 
and  gypfum. 

SPECIES   111. 

Magnefian  Stones  and  Aluminous  Stone's. 

Steatites  is  frequently  mixed  with  clay.  Its  fibres  are  found 
bedded  in  an  argillaceous  fubftanec.  Steatites  and  ferpentine 
are  fometimes  mixed  with  fchiftus. 

SPECIES  IV. 
Magnefian  Stones  and  Siliceous  Stones. 

Serpentine  is  found  mixed  with  veins  of  quartz,  feld  fpar 
fchorl,  &c. 

Afbeftos  and  amianthus  are  often  confounded,  and  fometimes 
incorporated  in  quartz  and  rock-cryftal. 

Mr.  De  Sauflure  has  defcribed  a  compound  ftone,  of  which 
the  quartz  is  white,  and  the  fteatites  green. 

At  Sterzing  in  Tyrol,  is  found  a  rock  formed  by  fchorl  and 
ferpentine. 

In  the  county  of  Mansfield  in  Saxony,  a  rock  has  been  difcov- 
cred,  compofed  of  jafper  and  afbeftos. 


Earthy  Mixtures,     StcMs,^  jri 


GENUS  IV. 

^ocks  or  Stones  formed  by  the  Mixture  of  Aluminous  Stones  with 
other  Species. 

SPECIES  I. 
Schiftus  and  Mica 

This  mixture  forms  feveral  primitive  mountains.  The  mica 
is  fometimes  in  plates  of  a  certain  thicknefs,  but  moft  commonr- 
ly  in  fmall  fragments  ;  and  the  ftone  affumcs  a  brilliant  argen- 
tine appearance,  which  renders  thefe  flones  agreeable  to  the  fighr. 
In  this  laft  cafe,  the  (tone  is  nearly  white,  fonorous,  and  fplits  in- 
to leaves  ;  whereas  it  is  blackifli,  and  lefs  hard,  when  the  mica 
is  difperfed  through  it  in  large  grains. 

Thefe  kinds  of  micaceous  fchifti  do  not  become  fpontaneouf- 
ly  decompofed.  They  differ  eflentially  from  the  pyritous  fchit- 
tus,  whofe  formation  appears  to  be  pofteriour  to  that  of  the  pref- 
cnt  fpecies. 

This  micaceous  fchiflus  is  a  primitive  (lone.  It  docs  not  in- 
clude minerals,  or  at  lead  very  rarely  5  aad  it  is  jiot  fpontane?- 
oufly  decompofed. 

SPECIES  II. 
Schiftus  and  Garnet. 

The  fchiftus  frequently  contains  garnets,  which  rife  in  protu- 
herances  in  its  texture,  and  feparate  its  llrata   from  each  other. 

The  garnet  is  cryftallized,  and  one  would  be  difpofed  to  af- 
iirm  that  this  ftone  had  increafed,  and  almoft  vegetated  in  th^ 
other,  which  ferves  as  its  covering.  It  is  probable  that  the  gar- 
net has  been  enveloped  by  this  pafte  of  fchiftus  ;  or  that  it  was 
formed  while  the  ftone  was  ftill  almoft  in  the  fluid  ftate. 

I  found  this  fchiftus  filled  with  garnets  in  the  bed  of  the  river 
Braniabiou,  in  the  diocefe  of  Alais. 

SPECIES  III. 

Schiftus,  Mica,  and  Quartz  mixed  in  fmall  fragments. 

The  Germans  call  this  compound  ftone  by  the  name  of  Gjieifs* 
It  deferves  to  be  included  among  the  quartzofe  and  filiceous 
ftones  ;  but  as  it  nearly  approaches  the  primitive  fchifti  we  have 
juft  treated  of,  ^^e  fhall  follow  the  natural  method  in  clafling  it 
here. 

The  texture  of  this  ftone  varies  greatly.  It  fometimes  forms 
a  rock  in  which  neither  ground  nor  fibres  can  be  diftinguiftjed  ; 
in  other  fpecimens  it  appears  to  be  divided  into  filaments  twift- 
ed  in  a  thoufand  manner^,  and  it  frequently  exhibits  a  lamellated 
|iard  texture. 


252  Earthy  Mmtures,     Stones, 

It  is  found  in  large  mafles  of  a  greyifh  green  colour,  with  itg 
furface  fhirjing,  and  poliflied  like  the  flate  ;  and  it  appears  to  be 
merely  a  fine  grained  granite,  the  minutenefs  of  whofe  parts  has 
fuffered  them  to  take  the  foliated  form  of  the  fchiftus. 

Mr.  Weigleb  has  analyfed  that  of  Friburg. 

SPECIES       iv. 
Schiftus  and  Schorl. 

The  mixture  of  thefe  two  (tones  is  common  enough.  The 
fchorl  is  fometimes  difperfed  in  very  minute  filaments,  which 
give  a  blackifh  tinge  to  the  mafs.  Its  form  is  often  prifmatick  ; 
in  which  cafe  the  fibres  of  the  fchiftus,  and  the  long  cryftals  of 
the  fchorl,  form  the  prifm  by  their  reunion. 

A  fchiftus  has  been  found  in  the  Pyrenean  mountains,  in 
v/hich  the  fchorl  is  fpread  from  fpace  to  fpace  in  the  form  of 
oblong  bodies,  and  equally  difperfed  over  the  whole  mafs. 

SPECIES      V. 
Clay  and  Quartz. 

This  conftitutcs  the  argillaceous  grit-ftone,  or  the  ftone  in 
which  fragments  of  quartz  are  united  together  by  an  argillaceous 
gluten. 

Several  varieties  of  grit-ftone  may  be  diftinguiflied.  It  is 
often  found  in  irregular,  coarfe,  and  compadl  mafles,  which  are 
made  into  mill-ftones,  or  ufed  for  paving,  &c. 

The  magnitude  of  the  fragments  of  quartz  renders  the  fur- 
face  more  or  lefs  rugged  ;  and  it  is  this  which  renders  it  proper 
for  certain  operations  of  trituration. 

When  its  grain  is  finer,  it  is  made  into  grind-ftones.  It  is 
"by  virtue  of  their  quartzous  principles  that  grind-ftones  emit 
fuch  numerous  fparks,  when  ftruck  with  the  fteel,  or  when  they 
iire  moved  with  rapidity  againft  any  tool  of  that  metal. 

Argillaceous  grit-ftone  is  fometimes  of  a  fcaly  texture  :  the 
Cos  Turcica  of  Wallerius,  and  the  ftone  ufed  for  fharpenin^ 
fcythes,  are  of  this  kind. 

Fine  grit-ftone,  compofed  of  impalpable  particles,  is  known 
by  the  name  of  Tripoli,  from  the  part  of  Africa  whence  it  fir  ft 
camCv  It  is  now  found  in  Rouergue,  in  Britanny,  Germany, 
and  elfewhere. 

The  porous  grit-ftone  called  Filtering-ftone,  on  account  of  its 
ufe,  is  of  the  fame  nature.  • 

Quartz  is  fometimes  mixed  with  mica.  Qur  province  contains 
\t  in  various  places. 


Earthy  Mixtures.     Sicnes,  253 

The  mica  is  like  wife  found  mixed, 

1.  With  feld  fpar,  according  to  Ferber  and  Kirwan. 

2.  With  fchorf,  at  Mont  hykie  in  Dalecarlia  in  Sweden,  and 
at  Sterzing  in  Tyrol. 

3.  With  garnets,  at  Paternion  in  Carinthia,  and  at  the  Car- 
pathian mountains  in  Hungary. 

4.  With  garnet  and  fchorl,  at  Greyner. — See  Muller. 

5.  With  quartz,  feld  fpar,  and  fghorl.  This  compofition 
forms  one  of  the  moll  common  granites. 

The  mixture  of  thele  ftones,  varied  in  the  proportion  of  their 
principles  or  elements,  forms  the  numerous  variety  of  granites; 
and  feveral  colours  likewife  modify  them  exceedingly. 

GENUS       V. 

Compound  Stones  formed  bv  the  Mixture  and  Re-union  of  Quartzofe 
Stones  with  each  other. 


SPECIES       I. 

Quartz  and  Schorl. 

The  quartz  is,  in  general,  white  in  this  ftone,  and  the  fchorl 
pf  various  colours.  Some  of  the  paving  flones  of  London  are 
of  this  fort,  according  to  Kirwan.  The  fchorl  is  likewife  found 
in  cryllals  within  the  quartz. 

SPECIES       II. 

Quartz  and  Feld  Spar. 

A  (tone  of  this  nature  was  brought  me  from  the  neighbour- 
hood of  Avenes.  The  mountain  from  which  the  fpecimen 
W'a3  detached,  contains  about  one  third  of  quartz.  The  reft  of 
the  rock  confills  of  rhomboidal  feid  fpar,  of  no  great  firmnefs 
of  texture,  and  conftantly  exhibiting  the  rhombus  in  its  fra<5lure, 

I  pollefs  a  very  fine  fpecimen  of  a  fimilar  rock,  which  was 
fent  me  from  Fahlun  in  Dalecarlia. 

SPECIES       III. 

Girt-ftone  and  Garnet. 

I  have  received  from  the  mines  of  Tallard,  near  GapinDau- 
phiny,  girt-ftcnes  with  garnets  of  one  or  two  lines  in  diameter 
jnterfperfed.  Thefe  garnets  r.re  difperfed  through  the  whole 
mafs;  at  the  diftance  cf  three  cr  four  lines  from  each  other. 


2^4  Earthy  Mixtures.     StmeSf 

SPECIES       IV. 

Quartz,  Feld  Spar,  and  Schorl. 

This  mixture  is  common,  and  forms  great  part  of  the  granites 
•on  our  globe. 

The  proportion  of  the  elements  of  this  rock  vary  greatly,  but 
the  forms  of  the  (tones  which  compofe  it  are  not  lefs  variable. 
The  fchorl  is  frequently  cryftalhzed  in  prifms ;  the  feld  fpar  al- 
moft  always  exhibits  rhomboidal  laminae,  on  breaking  the  ftone  ; 
the  quartz  very  feldom  exhibits  determinate  figures,  but  it  has 
neverthelefs  been  found  in  fuperb  cxyftals  at  Alencon  and  elfcr 
where. 

The  colour  of  thefe  itones,  likewife,  exhibits  an  infinity  of 
Shades.  .The  fchorl  is  ufually  black  ;  but  it  is  fometimes  found 
green,  and  even  white,  as  in  fome  granites  brought  from  Spain. 
The  feld  fpar  is  commonly  of  an  alhen  grey  ;  but  it  has  been 
obferved  of  a  flefh-colour,  of  a  milk  white,  of  a  dull  red,  Sec. 
The  moll  common  appearance  of  the  quartz  is,  that  of  a  fat 
and  vitreous  fubftance.     It  is  fometimes  black. 

SPECIES      V. 

•Fragments  of  Quartz  united  by  a  Siliceov!^  Cement 

We  may  here  clafs  the  quartzofe  plum-pudding  flones.  The 
cement  which  unites  thefe  pebbles  of  quartz,  which  are  com- 
monly rounded,  is  the  pafte  of  petro-filex.     Some  of  thefe  pud- 

xling-ftones  are  fo  compail,  and  their  fra£lure  is  fo  uniform, 
that  they  are   capable  of  the  moft  beautiful  polifh,  and  produce 

a  very  happy  effect  by  the  variety  of  colour  of  the  feveral  flints 

connedted  by  the  fame  gluten. 

SPECIES      VI. 

Jafper  and  Feld  Spar. 

This  jrock  is  known  by  the  name  of  Porphyry.  The  jafper 
compofes  the  ground,  and  the  feld  fpar  is  interfperfed  in  fmalj 
needles,  or  in  flat  paralieiopipedons. 

The  colour  of  porphyry  varies  prodigioully.  The  feld  fpar, 
which  enters  into  its  compofition,  is  either  white,  or  yellowifli, 
or  red  5  but  the  name  of  the  porphory  is  always  dependent  on 
the  colour  of  the  jafper.  The  jafper  is  fometimes  green  and 
fometimes  black,  and  in  fome  inftances  red  \  which  eflabliflies  a 
great  number  of  varieties. 


.     Earthy  Mixtures.     Stoms.  ice 

As  this  (lone  is  fufceptible  of  the  mofl:  beautiful  polifh,  it  has 
been  employed  as  an  ornament  •,  and  out  temples,  as  well  as  pri- 
vate houfes,  are  decorated  with  it. 

•  Mr.  Ferber  found  in  Tyrol  porphyry  m  prifmatick  columns, 
refembling  that  of  bafaltes  ;  a  circumftance  which  affords  a  fur- 
ther degree  of  probability  to  the  opinion  of  fucli  as  have  confid- 
cred  porphyry  to  be  a  volcanick  produdlion. 

Porphyry  is  found  in  Egypt,  in  Italy,  in  Germany,  in  Swe* 
den,  in  France,  &c.  Mr.  Dorthes  has  brought,  from  various 
niourttains  in  Auvergne,  fpecimens  of  porphyrick  bafaltes  in  ta- 
bles and  in  mafles,  containing  cryftals  of  feld  fpar,  well  formed, 
and  little  altered. 

He  obferved  that  the  rocks  of  Chevenon,  an  ancient  convent 
cf  Gramontin,  at  the  diftance  of  one  league  from  Artonne  in 
Auvergne,  were  very  beautiful  porphyry.  Mr.  Guettard  found 
it  likcwife  in  the  foreft  of  Efterelle  in  Provence. 

Mr.  Dorthes  has  defcribed  more  than  twenty  varieties  of  por- 
phyry thrown  up  in  pebbles  by  the  Mediterranean  upon  our 
coafts,  whither  they  are  brought  by  the  Rhone.  In  many  of 
thefe  are  found  tranfparent  quartz  with  the  prifmatick  formj  and 
cryftallized  feld  fpar. 

Porphyry  fufes  into  a  black  globule,  marked  with  white  points. 

The  fpecifick  gravity  of  re:d  porphyry  is  27.65 1,  and  that  of 
green  26.760. — Briflbn. 

Por^ihyry  fometimes  contains  fchorl.  Wallerius  has  defcribed 
it  "  Porphir  rubens,  cum  fpatho  fcintillante  albo,  et  bafalta 
nigro.'*^ 

SPIECIES     VI  r. 
Jafper  and  Garnet. 

This  (lone  has  been  difcovered  in  Iceland  :  the  ground  is  a 
green  jafper,  which  includes  ferruginous  garnets  cryftallized, 
and  of  a  red  colour. 


SPECIES   VIII. 

Jafper  and  Caleedony. 

The  mountain  of  Giants,  in  Bohemia,  affords  this  ftone.  It 
has  likewlfe  been  found  in  the  Carpathian  mountains,  near  Kaf- 
kau  in  Hungary.  A  ftone  has  likewife  been  obferved  at  Ober- 
ftein,  in  the  Palatinate,  compofed  of  agate  and  jafper. 


256  Earthy  Mixtures,     Stents* 

SPECIES       IX. 

Jafper  and  Quartz., 

This  compound  ftone,  called  Saxum  Sibericum  by  Linnaeus, 
has  been  found  in  Siberia,  and  alfo  near  Stutgard  in  the  Duchy 
of  Wirtemburg. 

SPECIES  X. 

Jafper  Quartz,  and  Feld  Spar 

This  ftone  is  found  in  the  environs  of  Geneva.  Its  ground  is 
a  jafper,  or  rather  a  petro-filex,  black,  opaque,  and  very  hard. 
This  matrix  is  interfperfed  with  fmall  rediangular  cryftals  of 
white  feld  fpar,  and  rounded  grains  of  tranfparent  quartz.  Mr. 
De  Sauffure,  who  has  defcribed  this  fpecies,  places  it  among 
the  porphyries. 

SPECIES      XI, 

Schorl,   Garnet,  and  Tourmaline. 

Mr.  Mullur  has  difcovered  in  Schneeburg,  a  mountain  of  the 
territory  of  Sterzing  in  Tyrol,  a  rock  of  this  kind,  containing 
large  cryftals  of  tourmaline,  which  include  fmall  cryftallized  gar- 
nets, tranfparent,  and  of  a  red  colour. 

Mr.  Ferber  affirms  that  he  found  between  Faiftritz  and  Car- 
nowitz  in  Stiria,  detached  pieces  of  green  fchorl,  which  enclofe 
large  red  garnets  :  he  adds,  that  this  fchorl  is  fometimes  fcaly, 
and  of  a  micaceous  texture. 

Mr,  De  Saufllire  has  found  in  the  environs  of  Geneva,  ftones 
v/orn  round  by  water,  which  were  compofed  of  fchorl  in  the 
mafs,  and  garnet. 

The  Mediterranean  Sea  throws  up  on  our  coaft  many  varieties 
of  rounded  pebbles  of  porphyry,  which  have  fchorl  for  their 
bads. 

GENUS  VI. 

Scper-compound  Stones,  or  fuch  as  refult  from  the  Mbcture  and  Re- 
union of  feveral  different  Genera. 

SPECIES      I. 

Petro-filex,  Alumine,  and  Calcareous  Spar. 

This  ftone  is  found  at  Schneeburg  in  Saxony. 


Earthy  Mixtures »    Stones,  257 


SPECIES      II. 
Clay,  Steatites,  and  CaJcarecrus  Spar. 
This  fpecies,  as  well  as  the  two  following,  are  comprifed  un- 
der the  name  of  Saxa  Glandulofa.     The  fteatites,  the  fpar,  and 
the  other  fubftances  are  difperfed  in  the  matter  which  forms  the 
ground  of  this  rock. 

SPECIES    III. 
Clay,  Zeolite,  Schorl,  and  Calcareous  Spar. 

SPECIES    IV. 

Clay,  Serpentine,  and  Calcareous  Spar. 

SPECIES  V. 
Serpentine,  Mica,  and  Calcareous  Spar. 

Mr.  Ferber  has  defcribed  this  laft  fpecies  under  the  name  of 
Polzevera  •,  a  denomination  fuggefted  to  him  by  the  place  where 
it  is  found.     See  his  Letters  on  Italy. 

SPECIES  vr. 

Serpentine,  Schorl,  and  Calcareous  Stone* 

This  (lone  furrounds  the  veins  of  the  mine  of  St.  Simon 
and  Jude,  at  Dognafta,  in  the  Bannat  of  Temefward  :  it  is  like- 
wife  found  in  copper  mines  of  Salka  ;  and  at  Hoferfchlag,  near 
Schnemniz,  in  Lower  Hungary. 

SPECIES    VII. 

Steatites,  Mica,  and  Garnets. 
This  ftone  is  found  at  Handol  in   Jempterland,  towards  the 
north  of  Sweden. — Born.  Ind.  FofT.  par.  ii. 

SPECIES  VIII. 

Steatites,  Mica,  and  Schorl. 

This  ftone  was  found  at  Salbury  in  Weftmanland,  a  province 
of  Sweden. — Born.  Ind.  FofT.  par.  ii. 

SPECIES.     IX. 

Garnets,  Quartz,  Mica,  and  Serpentine. 
This  contains  a  fmall  quantity  of   pyrites.     It   is  found  at 
Pufterthal  in  Tyrol, — See  Bruckman. 
2...I 


2^5^  27jf  DiamofiiT, 


SPECIES        X. 


Feld  Spar,  Quartz,  Mica,  Steatrtes. 

Several  granites  are  formed  by  a  mixture  of  this  natirfe. 
Such  are  found  at  Sunnefkog  in  Sweden,  and  at  Guten  HofF- 
nangfban  iiear  Altwofchitz  in  Bohemia  :  it  is  iho^  granites  fleatite 
'mixtus  of  Born. 


SPECIES       XI. 

Quartz,  Mica,  and  Clay. 

Tliis  rock  is  the  matrix  of  the  ore  of  tin  at  Platte,  and-  at 
Gottefgab  in  Bohemia. 

SPECIES     XI  I. 
Quartz,  Clay,  and  Steatites. 
This  is  found  at  Mount  St.  Godard  in  Switzerland. 

Concerning  the  Diamond. 

The  Diamond  forms  an  appendix  to  the  hiflory  of  ftoneS, 
Its  combuflibility  is  a  chara<^er  which  prevents  its' being  afiimi- 
lated  to  any  known  fpecies. 

The  diamond  was  long  confidered  as  the  hardefl:  and  moft 
ponderous  of  (tones,  as  well  as  the  only  one  which  did  not 
caufe  a  double  refraction  ;  b'it  fubrenuent  obfervations  have  de- 
ftroyed  thefe  early  notions.  The  adamantine  fpar  appears  to 
equal  it  in  hardnefs  ;  the  oriental  ruby,  and  the  jargon  of  Ceylon 
are  more  ponderous  ;  and  the  oriental  precious  ftones  exhibit 
one  refra£lion  only,  as  does  hkewife  the  phofphorick  fpar. 

This  precious  (lone  is  found  on  the  coaft  of  Coromandel, 
and  principally  in    the    kingdoms  of  Golconda   and   Vifapour. 

The  earth  which  ferves  as  its-  gangue  is  red,  ochreous,  and' 
foils  the  fingers. 

The  general  procefs  of  exploring  the  diamond  mines  or  earths 
confifts  in  mixing  the  earth  with  water,  after  which  the  fluid  is 
poured  off,  and  the  fand  which  remains  at  the  bottom  is  dried 
by  the  (Irong  heat  of  the  fun. — ^^See  the  Memoirs  of  the  Compte 
Marechal- 

Other  naturalifts  inform  us  that,  when  the  earths  have  been 
Washed,  the  refidue  is  left  to  dry,  and  is  fifted  in  baikets  made 
lor  the  purpofe.  The  workmen  afterwards  feek  for  the  dia- 
monds with  their  hands. 


The  Diamond,  259 

Biamohtls  in  their  native  flate  are  covered  with  two  crufts  ; 
4:he  one  earthy,  and  the  other  fparry. — Rome  de  Lille. 

When  lapidaries  undertake  to  work  them,  they  are  obliged  to 
iind  the  grain  of  the  ftone,  in  order  to  fpiit  or  cleave  the  dia- 
inond.  If  the  fracture  be  not  uniform,  they  call  the  ftone  a 
Mfrmond  of  nature.  The  hardnefs  of  the  diamond  is  fuch,  that 
it  refifts  the  moft  highly  polifhed  fteel  j  which  circumltancc 
renders  it  neceflary  to  attack  it  by  diamond  powder. 

The  manner  or  form  in  which  ^diamonds  are  cut,  diftin- 
guifnes  them  into,  rofe  diamonds^  and  brilliants,  or  brilliant  dia- 
rnonds.  The  brilliant  diamond  is  cut  into  facets  on  both  fides. 
The  variety  of  forms  given  to  thefe  facets,  and  their  difFereni: 
inclinations  with  refpejft.to  each  other,  multiply  the  refradlions, 
and  contribute  to  afford  thofe  reflections,  and  ftreams  of  pure 
and  vivid  light,  which  characterize  the  diamond. 

The  diamond  is  divided  in  two  -kinds  j  the  oriental  diamond 
and  the  Brazilian  diamond. 

The  oriental  diainond  cryftalli^es  in  o£lahedrons,  and  ex- 
hibits all  the  varieties  of  this  primitive  form. 

The  Brazilian  diamond  cryftallizes  in  dodecahedrons  :  It  is 
neither  fo  hard,  fo  heavy,  fo  perfect,  nor  fo  valuable,  as  the  ori- 
ental diamond. 

The  colcurlefs  diamond  has  a  fpecifick  gravity  which  is  la 
proportion  %  that  of  water  as  35.212  to  10.000.  Mr.  Briflbu 
has  derived  this  fpecifick  gravity  from  an  experiment  on  the 
Pitt  diamond  of  the  French  crown.  A  cubick  foot  of  this  dia- 
mond would  weigh  two  hundred  and  forty-fix  livres,  feven 
ounces,  five  gros,  fixty-nine  grains. 

The  diamond  is  fometimes  coloured  green,  violet,  black,  &c. 
The  green  are  the  moll  efteemed,  becaufe  they  are  the  moft, 
fcarce.  The  weight  of  coloured  diamonds  is  more  confiderable 
4:han  that  of  the  white  diamonds  :  becaufe  it  is  augmented  by 
the  v/eight  of  the  colouring  principle  which  is  of  a  metallick 
nature. 

•  The  brilliancy,  hardiiefs,  and  fcarcity  of  the  diamond  have 
prelerved  it  in  the  moft  extravagant  degree  of  eftimation.  A  di- 
amond is  laid  to  be  of  a  fine  water  when  it  prefents  no  defect 
or  fpot  ;  and  the  price  is  proportioned  to  its  purity. 

When  a  diamond  is  without  fault,  its  value  is  eftimated  ac- 
cording to  its  weight ;  which  is  determined  or  divide^!  into  ca- 
rats, each  carat  being  equivalent  to  about  four  grains. 

The  moft  beautiful  diamonds  hitherto  known  are — i.  Tiie 
two  In  the  cro^'n  of  the  king  of  France  ;  one  of  which  is  the 
"Grand  Sancy,  weighing  one  hundred  and  fix  carats  ;  and  the 
father  the  Pitt,  which  weighs  feven  gros,  twenty-five  grains  and 


26o  The  Diamonds 

one  fixteenth.  It  is  fourteen  lines  long,  thirteen  and  a  half 
broad,  and  nine  and  one  third  thick.  2.  The  diamond  whi<:h 
at  prefent  belongs  to  the  Czarina  weighs  feven  hundred  and  fev- 
enty-nine  carats.  The  emprefs  purchafedit  in  i772for  12  tons 
of  gold  (100,000  florins,)  and  granted  a  penfion  of  four  thou- 
fand  roubles  to  the  feller.  It  is  pretended  that  this  fine  diamond 
•was  one  of  thofe  which  ornamented  the  eyes  of  the  famous  ftatue 
Scheringham,  which  has  eight  eyes  and  four  heads  ;  and  that  it 
was  carried  off  by  a  French  deferter  who  had  procured  himfelf 
to  be  appointed  as  a  guard  to  the  temple  of  Brama.  This  dia- 
mond was  at  firft  fold  for  fifty  thoufand  livres,  afterwards  for 
about  four  hundred  thoufand  livres,  and  was  at  length  purchafed 
by  the  Emprefs  of  Ruffia. 

The  combuftibility  of  the  diamond  is  a  phenomenon  fuffi- 
ciently  interelling  to  induce  us  to  give  a  faithful  extrad  of  the 
principal  experiments  which  have  ferved  to  advance  our  knowl- 
edge upon  this  fubjedl:. 

Boyle  obferved,  long  fince,  that  the  diamond,  expofed  to  a 
violent  fire,  emitted  acrid  vapours. 

The  emperor  Francis  the  Firft  caufed  crucibles  to  be  expofed 
to  a  reverberatory  fire,for  twenty-four  hours,  into  which  veflels 
the  value  of  fix  thoufand  florins  in  diamonds  and  rubies  were 
put.  The  diamonds  difappeared,  but  the  rubies  were  not  alter- 
ed. Thefe  experiments  were  repeated  with  great  expenfe  :  and 
It  was  afcertained  that  the  diamond  loft  its  poliih,  fcaled  off,  and 
■was  dilTipated. 

The  Great  Duke  of  Tufcany,  in  1694,  caufed  experiments  to 
be  made  by  Mr.  Averoni  and  Targioni,  by  the  mirror  of  Tfchir- 
iiaufen,  and  it  was  found  that  the  diamonds  difappeared  in  a  few 
^ninutes. 

In  1772,  thefe  experiments  wererefumed  by  the  (kijful  chem- 
ifts  of  Paris^ — Darcet,  the  Comte  de  Laraguais,  Cadet,  Lavoifier, 
3Mitouard,  Macquer,  &c.  The  details  of  the  interefting  expe- 
riments made  on  this  fubje£l  may  be  feen  in  the  volumes  of  the 
Academy  of  Sciences,  and  the  Journeaux  de  Phyfique,  of  that 
year.     We  (hall  fimply  relate  the  refults. 

1.  Meflirs.  Darcet  and  the  Comte  de  Laraguais  proved  that 
the  diamond  is  volatilized  in  balls  of  porcelain. 

2.  Mr.  Macquer  took  notice  that  the  diamond  dilated  and 
fwelled  up  ;  and  that  a  blue  flame  was.  obfervable  on  its  furface^ 
during  the  combuftion. 

3.  Meflis.  Lavoifier  and  Cadet  proved,  that  the  combuftion 
of  diamonds  in  clofed  vefl~els  ceafed  as  foon  as  the  oxigene  was 
deftroyed ;  and  that  the  diamond  did  not  burn  but  in  propor- 
tion to  the  oxigene  prefent,  like  all  other  gombuftible  fubftaucea. 


Geological  Ohfervat'wns,  261 

The  jewellers,  who  expofe  their  diamonds  to  very  violent  fires 
to  render  them  colourlefs,  are  careful  to  wrap  them  up  in  fuch  a 
manner  as  to  fecure  them  from  the  contaft  of  air. 

Mr.  De  SaulTure  burned  a  diamond  by  the  blow-pipe  ;  Mr. 
Lavoifier  has  proved  that,  when  it  is  expofed  to  the  burning 
glafs,  a  dull  arifes  which  precipitates  lime-water. 

The  diamond  is  therefore  a  combultible  fubftance,  which 
burns  in  the  fame  manner  as  other  bodies.  This  ftridt  and  ac- 
curate confequence  is  deduced  from  all  the  experiments  which 
can  be  imagined  to  acquire  a  perfect  demonftration. 

Within  a  few  years  chemifts  have  difcovered  a  very  fingular 
Hone,  to  which  the  name  of  Adamantine  Spar  has  been  given 
by  Bergmann. 

It  is  black,  and  fo  hard  that  its  powder  may  be  ufed  to  cut 
the  diamond  ;  from  which  circumftance  it  has  obtained  its 
name. 

It  cryftallizes  in  hexahedral  or  fix-fided  prifms,  two  of  which 
are  large,  and  four  fmall. 

It  fpecifick  gravity  is  38.732  with  refpecl  to  water,  which  is 
aflumed  at  10.000.  See  BriiTon. — The  cubick  foot  weighs  two 
hundred  and  feventy-one  livres,  one  ounce,  feven  gros,  fixty- 
three  grains. 

The  moft  violent  fire  produces  only  a  flight  foftening  of  this 
fpar,  according  to  the  experiments  of  Mr.  Lavoifier. 

The  analyfis  made  by  Mr.  Klaproth  of  this  flone,  has  exhib- 
ited a  peculiar  earth,  which  is  fufpecled  to  be  likewife  one  of  the 
principles  of  precious  ftones,  &c. 


GENERAL  VIEWS 

RESPECTING 

The  Decotnpofttions  and  Changes  to  ivhich  the  Stony   Part  of  tur 
Globe  has  been  fubjeEied^ 

If  it  were  permitted  man  to  follow,  during  feveral 
ages,  the  various  changes  which  are  produced  on  the  furface  of 
our  globe  by  the  numerous  agents  that  alter  it,  we  fhould  at  this 
time  have  been  in  poflefTion  of  the  moft  valuable  information 
refpecking  thefe  gi^at  phenomena  :  but  thrown,  as  we  are,  al- 
moft  by  accident,  i!^)on  a  fmall  point  of  this  vaft  theatre  of  ob- 
fervation;  we  fix  our  attention  for  a  moment  upon  operations 


262  ideological  Ohfcrvations. 

which  have  err^ployed  the  works  of  nature  for  ages  ;  and  we 
aic  unable  either  to  perceive  or  to  foretel  the  refults,  becaa fc 
feveral  ages  are  icarcely  lufficient  to  render  the  etFecls  or  chan- 
ges perceptible.  Nature  never  ceafes  to  exift  :  her  a<fl:ivity  has 
been  coeval  with  the  exiftence  of  matter  ;  her  operations  are  not 
circumfcribed  within  limited  times ;  (lie  difpofes  of  whole  ages 
in  the  arrangemen:  of  her  combinations  •,  while  man  can  com- 
mand no  more  than  a  few  inftants,  and  himfelf  difappears  at  the 
moment  wherein  he  has  proceeded  fo  far  as  to  conned:  a  few 
fa£ls  together.  Hence,  no  doubt,  it  arifes,  that  nature  is  incom- 
prehenfible  in  fome  of  her  operations,  and  inimitable  in  all  thofe 
which  require  a  long-  feries  of  time. 

It  muft  be  allov/ed  that  thofe  men  who,  by  the  mere  efforts  of 
their  imagination,  have  endeavoured  to  form  ideas  refpefting  the 
conftruftion,  and  the  great  phenomena  of  this  globe,  have  nu- 
merous titles  to  our  indulgence.  In  their  proceedings  we  be- 
hold the  efforts  of  genius,  tormented  with  the  defive  of  acquir- 
ing knowledge,  and  irritated  at  the  profpect  of  the  fcanty  means 
■which  nature  has  put  in  its  power  :  and  when  thefe  naturalifls, 
fuch  as  Mr.  DeBuffon,  have  polTeffed  the  power  of  embellifning 
their  hypotheles  with  every  ornament  which  imagination  and  el- 
oquence can  furnilh,  either  as  initruments  of  iilufion  or  enter* 
tainment,  we  ought  to  confider  ourfelves  indebted  to  them. 

For  our  part,  we  (liall  confine  ourfelves  to  exhibit  a  fev/  ideas 
refpe6ling  the  fuccellive  decompofitions  of  our  planet,  and  Ihall 
endeavour  to  avjoid  every  departure  from  obfervation  and  matter 
of  faa. 

The  flightefl  obfervation  (hews  us  that  living  beings  are  kept 
up  and  perpetuated  only  by  fucceffive  decompofitions  and  com- 
binations. A  flight  view  of  the  mineral  kingdom  exhibits  the 
fame  changes  \  and  our  globe,  in  all  its  productions,  prefents 
continual  modifications,  and  a  circle  of  activity,  u^hich  might 
appear  incompatible  with  the  apparent  inertia  of  lithologick  pro- 
duas. 

In  order  to  arrange  our  ideas  with  greater  regularity,  we  may 
confider  this  globe  in  two  different  flates.  We  will  firft  exam- 
ine the  primitive  rock  which  forms  the  nodule  or  central  part. 
This  appears  to  contain  no  germ  of  life,  includes  no  remains  or 
part  of  any  living  being,  and  from  evttry  circumftance  appears 
to  have  been  of  primitive  formation,  anteriour  to  the  creation  cf 
animated  or  vegetating  bodies.  We  fliall  purfuc  the  various 
changes  which  are  daily  produced  by  the  dedruaive  aaion  of 
fuch  a^Qjents  as  alter  or  modify  this  fubflance.% 

We  (hall  then  proceed  to  examine  what  ^nes  have  been  fuc- 
cefTively  placed  upon  this,  and  what  are  the  decompofitions  to^ 
which  thefs  fecondary  rocks  have  been  fubjeaed. 


Geclogkal  OSfervaiions.  26:^. 

I.  The  obfervations  of  naturalifts  all  unite  to  prove,  that  the 
central  part  of  the  globe  confills  cf  the  flone  known  by  the 
name  of  Granite.  The  profound  excavations  which  the  art  of 
man,  or  currents  of  water,  have  made  in  the  furface  of  our  plan- 
et, have  all  uncovered  this  rock,  and  have  been  incapable  of  pen- 
etrating lower  :  we  may  therefore  confMer  this  fubftance  as  the 
nucleus  of  the  globe  ;  and  upon  this  fubftance  it  is  that  all  mat- 
ters of  pofteriour  formation  reft. 

Granite  exhibits  many  varieties  in  its  form,  compofition,  and 
difpofition  :  but  it  in  general  confifts  of  an  afTemblage  of  certain 
filiceous  ftones,  fuch  as  quartz,  fchorl,  feld  fpar,  mica,  &c.  ;  and 
the  more  or  lefs  confiderable  magnitude  of  thefe  elements  of 
granite,  has  caufed  it  to  be  divided  into  coarfe-grained  granite, 
and  fine-grained  granite. 

It  appears  to  me  that  there  Is  rro  denying  but  that  thefe  rocks 
owe  their  arrangenrrent  to  water  :  and  if  we  may  be  permitted 
to  recur,  by  an  effort  of  the  imagination,*  to  that  epocha  in' 
which,  according  to  facred  and  profane  hiftorians,  the  water  and 
earth  were  confounded,  and  the  confufed  mixture  of  all  princi- 
ples formed  a  chaos,,  we  fhall  fee  that  the  laws  of  gravity  inhe- 
rent in  matter  muffe  have  carried  it  dov/n,  and  neceffarily  produc- 
ed the  arrangement  which  obfervatlon  at  prefent  exhibits  to  us. 
The  water,  as  the  leaft  heavy,  muft  have  purified  itfelf,  and 
arifen  to  the  furface  by  a  filtration  through  the  other  materials  :■ 
while  the  earthy  principles  muft  have  prcrcipitated,  and  formed 
a  mud,  in  which  all  the  elements  of  ftones  were  confounded. 
In  this  very  natural  order  of  things,  the  general  law  of  aflinities^ 
which  continually  tends  to  bring  together  all  analagous  parts, 
muft  have  exerted  itfelf  with  its  whole  adlivity  upon  the  princi- 
ples of  this  almoft  fluid  pafte  ;  and  the  refult  muft  have  been  a 
number  of  bodies  of  a  more  definite  kind,  in  cryftals  more  or 
lefs  regular:  and  from  this  muddy  fubftance,  in  which  the  prin- 
ciples of  the  ftones  were  confounded  that  compofe  the  granite^ 
a  rock  muft  have  been  produced,  containing  the  elementary 
ftones  all  in  poflefPion  of  their  diftinct  forms  and  characters. 
In  this  manner  it  is  that  we  obferve  falts  of  very  different  kinds 
develope  themfelves  in  waters  which  hold  them  ni  folution  :  and 
in  this  m.anner  it  ftiii  happens  that  cryftals  of  fpar  and  gypfum^ 
are  formed  in  clays  vi'hich  contain  their  component  parts. 

*  This  is  the  firft  and  the  laft  fuppofition  in  which  I  Hi:)!!  indulge  my- 
fclf.  It  is  a  conje(5ture,  however,  wiiich  is  indifferent  vviih  refpct^t  to  the 
bafisof  the  fubjcv^l:  itll-IF;  finceit  relates  only  to  an  hypothefis  refpeding. 
the  manner  in  which  a  rod:  might  be  fo:med  that  at  prefent  exifts,  and 
whofe  decoinpofitions  alone  can  form  the  fuhievftof  our  oblervations. 


264  Geological  Ohfervations. 

It  may  eafily  be  conceived  that  the  laws  of  gravitation  mufi 
have  influenced  the  arrangement  and  difpofition  of  the  produftg. 
The  moil  grofs  and  heavy  bodies  muft  have  fallen,  and  the  light- 
eft  and  moll  attenuated  fubftances  muft  have  arranged  thcm- 
felves  on  the  furface  of  the  foregoing  :  and  this  it  is  which  con- 
ftitutes  the  primitive  fchifti,  the  gneis,  the  rocks  of  mica,  &c. 
which  commonly  repoie  upon  mafles  of  coarfe-grained  granite. 

The  difpofition  of  the  fine-grained  granite  in  ftrata  or  beds, 
appears  to  me  to  depend  on  this  pofition,  and  the  finenefs  or 
tenuity  of  its  parts.  Being  placed  in  immediate  conta£t  with 
water,  this  fluid  muft  naturally  have  influenced  the  arrangement 
which  it  prefents  to  us  ;  and  the  elements  of  this  rock  being 
fubje£led  to  the  efFecl  of  waves,  and  the  adtion  of  currents, 
muft  have  formed  ftrata. 

The  rocks  of  granite  being  once  eftabliflied  as  the  nucleus  of 
our  globe,  we  may,  from  the  analyfis  of  its  conftituent  principles, 
and  by  attending  to  the  action  of  the  various  agents  capable  of 
altering  it,  follow  the  degradations  to  which  it  has  been  fubjedl- 
ed,  ftep  by  ftep. 

Water  is  the  principal  agent  whofc  efl^efls  we  fliall  examine. 

This  fluid,  colle£led  in  the  cavity  of  the  ocean,  is  carried  by 
the  winds  to  the  tops  of  the  moft  elevated  mountains,  where  it 
is  precipitated  in  rain,  and  forms  torrents,  which  return  with 
various  degrees  of  rapidity  into  the   common  refervoir. 

This  uninterrupted  motion  and  fall  muft  gradually  attenuate 
and  wear  away  the  hardeft  rocks,  and  carry  their  pulverulent 
parts  to  diftanccs  more  or  lefs  confiderable.  The  adion  of  the 
air,  and  varying  temperatures  of  the  atmofphere,  facilitate  the 
attenuation  and  the  deftruckion  of  thefe  rocks.  Heat  dries  their 
furface  and  renders  it  more  acccffible  and  more  penetrable  to 
the  water  which  fucceeds  -,  cold  divides  them,  by  freezing  the 
water  which  has  entered  into  their  texture  ;  the  air  itfelf  aflx)rds 
the  carbonick  acid,  which  attacks  the  lime-ftone,  and  caufes  it  to 
cfllorefce  -,  the  oxigene  unites  to  the  iron,  and  calcines  it ;  info- 
much  that  this  concurrence  of  caufes  favours  the  difunion  of 
principles  ;  and  confcquently  the  adlion  of  water,  which  clears 
the  furface,  carries  away  the  produdls  of  decompofition,  and 
makes  preparation  for  a  fucceeding  procefs  of  the  fame  nature. 

The  fiirft  effe(ft  of  the  rain  is  therefore  to  deprefs  the  moun- 
tains. But  the  ftones  which  compofe  them  muft  refift  in  pro- 
portion to  their  hardnefs  5  and  we  ought  not  to  be  furprifed 
when  we  obferve  peaks  which  have  braved  the  deftruflive  ac- 
tion of  time,  and  ftill  remain  to  atteft  the  primitive  level  of 
the  mountains  which  have  difappeared.  The  primitive  rocks^ 
^ike  inacceflfiblc  to  the  injuryof  ages  as  to   the   animated  bc-» 


Geological  Ohfervations,  265 

lags  which  cover  lefs  elevated  mountains  with  their  remains, 
may  be  confidcred  as  the  fource  or  origin  of  rivers  and  ftreams. 
The  water  which  falls  on  their  fummits,  flows  down  in  torrents 
by  their  lateral  furfaces.  In  its  courfe  it  wears  away  the  foil 
upon  which  it  inceffantly  a£f s.  It  hollows  out  a  bed,  of  a  depth 
proportioned  to  the  rapidity  of  its  courfe,  the  quantity  of  its  wa- 
ters, and  the  hardnefs  of  the  rock  over  which  it  flows  \  at  the 
fame  time  that  it  carries  along  with  it  portions  and  fragments 
of  fuch  itones  as  it  loofens   in  its  courfe. 

Thefe  ftones,  rolled  along  by  the  water,  muft  flrike  together, 
and  break  off  their  projecting  angles:  a  procefs  that  muft 
quickly  have  afforded  thofe  rounded  flints  \vhich  form  the  peb- 
bles of  rivers.  Thefe  pebbles  are  found  to  diminifh  in  fizc,  in 
proportion  to  the  diftance  from  the  mountain  which  affords 
them  5  and  it  is  to  this  caufe  that  Mr.  Donhes  has  referred 
the  difproportionate  magnitude  of  the  pebbles  which  form  our  an- 
cient worn  flones,  when  compared  with  thofe  of  modern  date  : 
for  the  fea  extending  itfelf  formerly  much  more  inland,  in  the 
dir€£lionof  the  Rhone,  the  flones  which  it  received  from  the 
rivers,  and  threw  back  again  upon  the  fhores,  had  not  run 
through  fo  long  a  fpace  in  their  beds  as  thofe  which  they  at  pre- 
fent  pafs  over.  Thus  it  is  that  the  remains  of  the  Alps,  carried 
along  by  the  Rhone,  have  fucceffively  covered  the  vafl  interval 
Compriled  between  the  mountains  of  Dauphiny  and  Viva- 
rais  ;  and  are  carried  into  our  feas  which  depofite  them  in  fmall 
pebbles  on  the  (bore. 

The  pulverulent  remains  of  mountains,  or  the  powder  which 
refults  from  the  rounding  of  thefe  flints,  are  carried  along  with 
greater  facility  than  the  flints  themfelves  :  they  float  for  a  long 
time  in  the  water,  v/hofc  tranfparence  they  impair  ;  and  when 
thefe  fame  waters  are  lefs  agitated,  and  their  courfe  becomes 
fiackened,  they  are  dcpofited  in  a  fine  and  light  pafte,  forming 
beds  more  or  lefs  thick,  and  of  the  fame  nature  as  that  of  the 
rocks  to  which  they  owe  their  origin.  Thefe  (trata  gradually 
become  drier  by  the  agglutination  of  their  principles  ;  they  be- 
come confiftent,  acquire  hardnefs  and  form  filiceous  clays,  {^iX^-ii^ 
petrofilex,  and  all  the  numerous  clafs  of  pebbles  which  are  found 
difperfed  in  Itrata,  or  in  banks,  on  the  ancient  beds  of  rivers. 

Mr.  Pallas  has  obferved  the  tranlition  of  clay  to  the  (late  of 
filex  in  the  brook  of  Sunghir,  near  Wolodimir.  Mr.  J.  W. 
Baumer  has  likewife  obferved  it  in  Upper  Heffe. 

The  mud  is  much  more  frequently  depofited  in  the  intcrftices 
left   between   the  rounded  flints  themfelves,  which  intervals  it 
fills,  and  there  forms  a  true  cement  that  becomes  hard,  and  con- 
flit  utes  the  compound  ftones  known  by  the  nam.e  of  pudding- 
2...K 


,..'  '  Geolcgical  Ohfefvatlons. 

flones  and  grit-ftones  ;  for  thefe  two  kinds  of  flone  do  not  ap- 
l^car  to  me  to  differ  but  in  the  coarfcnefs  of  the  grain  which  forms- 
them,  and  the  cement  which  connects  them  together. 

We  fometimes  obferve  the  granite  fpontaneoully  decompofed* 
The  texture  of  the  ftones  which  form  it  has  been  deftroyed  ; 
the  principles  or  component  parts  are  difunited  and  feparated,- 
and  they  are  gradually  carried  away  by  the  waters.  I  have  ob- 
ferved  near  Mende,  towards  Caillenouvel,  the  moft  beautiful  ka- 
olin on  the  furface  of  a  granite,  in  a  ftate  of  decompofition  ;  and 
this  fame  rock  is  decompofsd  in  feveral  other  parts  of  our  prov- 
ince. It  appeared  to-me  that  the  feld  fpar  was  particularly  fub- 
jtdi  to  be  altered  the  firft. 

Moft  filiceous  ftones,  formed  by  the  depofition  of  fluvia- 
tilc  waters,  and  hardened  by  the  lapfe  of  time,  are  eafily  fub- 
ie£ledto  a  fecond  decompofition.  Iron  is  the  principal  agent  of 
thefe  fecondary  alterations  ;  and  its  calcination  determined  by 
air  or  water,  produces  a  difunion  of  principles.  Nature  may 
be  obferved  in  this  procefs,  by  an  attentive  examination  of  fuch 
alterations  as  gun  flints,  varoilites,  porphyries,  ja:fpers,  and  the 
like  are  fubjected  to. 

The  decompofition  of  flints,  cakedonies,  agates,  and  generally" 
all  ftones  of  this  kind  which  pofl^efs  a  certain  decree  of  tranfpar- 
ence,  appears  to  me  to  be  referable  to  the  volatilization  of  the 
water  which  forms  one  of  their  principles,  and  is  the  caufe  of 
their  tranfparency; 

Thefe  ftones  may  be  confidered  as  commencements  of  cryf- 
talUzation  •,  and,  when  the  water  is  diflipated,  they  efliorefce  af- 
ter the  manner  of  certain  neutral  falts.  Hence  it  arifes  that  the 
decompofition  is  announced  by  opacity,  a  white  colour,  lofs  of 
confiilence  and  hardncfs  ;  and  terminates  by  forming  a  very 
attenuated  powder,  fometimes  of  extreme  whitenefs.  It  is  this 
decompofition,  more  particularly,  which  forms  clays. 

There  are  ffints  whofe  alterations  form  eflTervefcent  marles. 
Thefe  do  not  appear  to  me  to  be  of  the  nature  of  primitive 
rocks  ;  they  have  the  fame  origin  as  the  calcareous  ftones,  from 
which  they  diflxir  only  in  confequence  of  a  very  confiderable' 
proportion  of  clay.  The  ftones  which  we  fo  abundantly  find  of 
this  nature  around  us,  among  calcareous  decompofitions,  may 
be  confidered  as  of  this  kind. 

Water  filtrating  through  mountains  of  primitive  rock,  fre- 
quently carries  along  v/ith  it  very  minutely  divided  particles  of 
quartz  *,  and  proceeds  to  form  by  depofition,  ftaladtites,  agates, 
rock  cryftal,  &c. 

Thefe  quartzofe  ftala£lites  differently  coloured,  are  of  a  form- 
ation conivderably  analagous  to  that   of  calcareous   alabaft^rs  >- 


.Geological  'Obfefvaiims,  267 

/:snd  we  perceive  no  other  difference  between  them  than  that  of 
•their  conftituent  parts. 

III.  Thus  far  we  have  exhibited,  in  a  few  words,  the  princi- 
,pal  changes,  and  various  modifications,  to  which  the  primi- 
tive rocks  have  been  fubje(fled.  We  have  not  yet  obferved  ei- 
ther germination  or  life  ;  and  the  metals,  fulphur,  and  bitumens, 
have  not  hitherto  prefented  themfelves  to  our  obfervation. 
Their  formation  appears  to  be  pofteriour  to  the  exiftence  of  this 
primitive  globe  ;  and  the  alterations  and  decompofitions  which 
now  remain  to  be  enquired  into,  appear  to  be  produced  by, the 
dais  of  living  or  organized  beings. 

On  the  one  hand,  we  behold  the  numerous  clafs  of  (hell  ani- 
mals, which  caufe  the  (tony  mafs  of  our  globe  to  increafe  by 
their  remains.  The  fpoils  of  thefe  creatures,  long  agitated  and 
driven  about  by  the  waves,  and  more  or  lefs  altered  by  collifion, 
form  thofe  ftrata  and  banks  of  lime-ftone,  in  which  we  very  of- 
ten perceive  imprefTions  of  thofe  (hells  to  which  they  owe  their 
.origin. 

On  the  other  hand,  we  obferve  a  numerous  quantity  of  veg- 
etables that  grow  and  perifh  in  the  fea  5  and  thefe  plants  like- 
wife,  depofited  and  heaped  together  by  the  currents,  form  ftrata, 
which  are  decompofed,  lofe  their  organization,  and  leave  all  the 
principles  of  the  vegetable  confounded  with  the  earthy  princi- 
ple. It  is  to  this  fource  that  the  origin  of  pit-coal,  and  fecond- 
ary  fchiltus,  is  ufually  attributed  ;  and  this  theory  is  eftablifhed 
on  the  exiftencecf  the  texture  of  .decompofed  vegetables  very 
ufually  feen  in  fchifti  and  coal.;  and  likewife  on  the  prefence  of 
iliells  and  fifh  in  moll  of  thefe  produQs. 

It  appears  to  me  that  the  formation  of  pyrites  ought  to  be  at- 
tributed to  the  decompofition  of  vegetables :  It  exifts  in  great- 
er or  lefs  abundance  in  all, fchifti  and  coal  I  have  found  a 
wooden  fliovel  buried  in  the  depofitions  of  the  river  De  Ceze, 
converted  into  jet  and  pyrites.  The  decompofition  of  animal 
fubltances  may  be  added  to  this  caufe  ;  and  it  appears  to  me 
.to  be  a  confirmation  of  thefe  ideas,  that  we  find  many  fhells 
pafled  to  the  ft  ate  of  pyrites. 

Not  only  the  marine  vegetables  form  confiderable  ftrata  by 
their  decompofition  ;  but  the  remains  of  thofe  whichgrowon  the 
-furface  of  the  globe  ought  to  be  confidered  among  the  caufes  or 
agents  which  concur  in  producing  changes  upon  that  furface. 

We  fhall  feparately  confider  how  much  is  owing  to  each  of 
.thefe  caufes  ;  and  fhall  follow  the  effe£ls  of  each,  as  if  that  caufe 
alone  were  employed  in  modifying  and  altering  our  planet. 

I.  The  calcareous  mountains  are  conltantly  placed  upon  the 
^fv^riace  of  the  primitive  mountains  j  and  though  a  few  folitary 


268  Geolcgtcal  Obfervations, 

obfervations  prefent  a  contrary  order,  we  ought  to  conficler  this 
inverfion  and  derangement  as  produced  by  (liocks  which  have 
changed  the  primitive  difpofition.  I  mult  obferve  alfo  that  the 
diforder  is  fometimes  merely  apparent ;  and  that  fome  natural- 
ifts  of  little  information  have  deicribed  calcareous  mountains  as 
inclining  beneath  the  granite,  becaufe  this  laft  pierces,  as  it  were, 
through  the  envelope,  rifes  to  a  greater  height,  and  leaves  at  its 
feet,  almofl  beneath  it,  the  calcareous  remains  depofited  at  its 
bafe. 

Sometimes  even  the  lime-flone  fills  to  a  very  great  depth  the 
crevices  or  clefts  formed  in  the  granite.  I  have  ittn  in  Gevau- 
<ian,  towards  Florae,  a  profound  cavity  in  the  granite  filled  with 
calcareous  ftone.  This  vein  is  known  to  poflefs  a  depth  of  more 
than  one  hundred  and  fifty  toifes,  with  a  diameter  of  about  two 
cr  three. 

It  likewife  happens  frequently  enough  that  fuch  waters  as  are 
loaded  with  the  remains  of  the  primitive  granite,  heap  them  to- 
gether, and  form  fecondary  granites,  which  may  exift  above  the 
calcareous  Hone. 

Thefe  calcareous  mountains  are  decompofed  by  the  combined 
a<5lion  of  air  and  water  ;  and  the  produ6l  of  their  decompofition 
fomtiimes  forms  chalk  or  marie. 

The  iightnefs  of  this  earth  renders  it  eafy  to  be  tranfpcrted 
by  water  ;  and  this  fluid,  which  does  not  poflefs  the  property 
of  holding  it  in  folution,  foon  depofites  it  in  the  form  of  gurhs, 
alabafters,  ftala6tites,  &c.  Spars  owe  their  formation  to  no  other 
caufe.  Their  cryftallizatlon  is  poileriour  to  the  origin  of  calca- 
reous mountains. 

Waters  wear  down  and  carry  away  calcareous  mountains  with 
greater  eafe  than  the  primitive  mountains  ;  their  remains  being 
very  light,  are  rolled  along,  and  more  or  lefs  worn.  The  frag- 
ments of  thefe  rocks  are  fometimes  connected  by  a  gluten  or 
cement  of  the  fame  nature  ;  from  which  procefs  calcareous  grit 
and  breccias  arife.  Thefe  calcareous  remains  formerly  depolk- 
ed  themfelves  upon  the  quartzofe  fand  •,  and  the  union  of  prim- 
itive matter  and  fecondary  products,  gives  rife  to  a  rock  of  a  mix- 
ed nature,  which  is  common  to  our  province. 

2.  The  mountains  of  fecondary  fchillus  frequently  exhibit  to 
lis  a  pure  mixture  of  earthy  principles,  without  the  fmalleft  vef- 
tige  of  bitumen.  Thefe  rocks  aflt)rd,  by  analyfis,  filex,  alumine, 
magnefia,  lime  in  the  ftate  of  carbonate,  and  iron  •,  principles 
which  are  more  or  lefs  united,  and  confequently  acceffible  in 
various  degrees  to  the  adlions  of  fuch  agents  as  deltroy  the  rocks 
hitherto  treated  of. 


Geological  Obfervatlons.  26 i) 

Thefe  fame  principles  when  difanited,  and  carried  away  by- 
waters,  give  rife  to  a  great  part  of  the  ilones  which  we  have  com- 
prifed  in  the  magnefian  genus.  The  fame  elements,  v/orn  down 
by  the  waters,  and  depofited  under  circumftances  proper  to  fa- 
cilitate cryftallization  form  the  ichcrls,  tourmaline,  garnets,  c^c. 

We  do  not  pretend  by  this  to  exclude  and  abfolutely  rcje<^ 
the  fyftem  of  fuch  naturahils  r.s  attribute  the  formation  of  mag- 
iiefia  Itones  to  the  decompoiition  of  the  primitive  rocks.  But 
we  think  that  this  formation  cannot  be  objedled  to  for  feveral  of 
them,  more  cf^iecially  fuch  as  contain  magnefia  in  the  greateft 
abundance. 

It  frequently  happens  that  the  fecondary  fchifll  are  interfperf- 
ed  with  pyrites  ;  and,  in  this  cafe,  the  flmple  contact  of  air  and 
water  facilitates  their  decompofition.  Sulphurick  acid  is  thus 
formed,  which  combines  with  the  various  conllitucnt  principles 
of  the  ftone  ;  whence  refult  the  fulphates  of  iron,  of  magnefin, 
of  alumine,  and  of  lime,  which  efTiorefce  at  the  furface,  and 
remain  confounded  together.  Schifti  of  this  nature  are  v/roughc 
in  m.oit  places  v/here  alum  works  have  been  eftablifned  ;  and 
the  moft  laborious  part  of  this  undertaking  confifls  in  feparating 
the  fuiphates  of  iron,  of  lime,  and  of  magnefia  from  each  other, 
which  itre  mixed  together.  Sometimes  the  magnefia  isfo  abun- 
dant that  its  fulphate  predominates  :  I  have  feen  mountains  of 
fchiftus  of  this  nature.  The  fulphate  of  lime  being  very  fpar- 
ingiy  fohihle  in  water,  is  carried  away  by  that  liquid,  and  de- 
pofited  to  form  gypfum  *,  while  the  other  m.ore  foluble  faits  re- 
maiinng  fufpended,  form  vitriol ick  mineral  waters. 

The  pyritous  fchifti  are  frequently  impregnated  with  bitumen, 
and  the  proportions  conftitute  the  various  qualities  of  pit-coal. 

It  appears  to  me  that  we  may  lay  it  down  as  an  incontedible 
principle,  that  the  pyrites  is  abundant  in  proportion  as  the  bitu- 
minous principle  is  more  fcarce.  Hence  it  arifes,  that  coals  of  a 
bad  quality  are  the  moft  fulphureous,  and  deflroy  metallick  vefTels 
by  converting  them  into  pyrites.  The  focus  of  volcanoes  ap- 
pears to  be  formed  by  a  fchiltus  of  this  nature  j  and  in  the  anal- 
yfes  of  the  Itony  matters  which  are  ejefted  we  find  the  fime. 
principles  as  thofe  which  conftitute  this  fchiftus.  We  ought 
not  therefore  to  be  much  furprized  at  finding  fchorls  among  vol- 
canick  produfls  ;  and  ftill  lefs  at  obferving  that  fubterranean 
fires  throw  fulphurick  falts,  fulphur,  and  other  analogous  pro- 
ducts out  of  the  entrails  of  the  earth. 

3.  The  remains  of  terreftrlal  vegetables  exhibit  a  mixture  of 
primitive  earths  more  or  lefs  coloured  by  iron  :  we  may  there- 
jfore  confider  thefe  as  a  matrix  in  which  the  feeds  of  all  ftony 
combinations  are  difperfed.     The  earthy  principles  nfibrt  them- 


270  _  Geological  Ohjervations. 

felves  according  to  the  laws  of  their  affinities  ;  and  form  cry  flat  l 
of  fpar,  of  phifter,  and  eveu  the  rock  cryftals,  according  to  all 
appearance  :  for  we  find  ochreous  earths  in  which  thefe  cryftals 
•are  abundantly  difperfed,;  we  fee  them  formed  almoft  under  our 
eyes.  I  have  frequently  obferved  indurated  ochres  full  of  thcfc 
,cry(lals  terminating  in  two  pyr?„mids. 

The  ochreous  earths  appear  to  qie  to  deferye  the  greateft  at- 
tention of  naturalills.  They  conftitute  one  of  the  mod  fertile 
means  of  adion  which  nature  employs  ;  and  it  is  even  in  earths 
nearly  fimilar  to  thefe  that  flie  elaborates  the  diamond,  in  the 
rkingdoms  of  Golconda  and  Vifapour.  If  it  were  allowable  to 
indulge  in  a  fid^ion  purely  poetical,  we  might  affirm  that  the  el- 
ement of  fire,  fo  far  from  being  loft  by  the  difperfion  of  thecom- 
buflible  principles  of  vegetables,  becomes  purified  to  form  this 
precious  flone  fo  eminently  combuflible  ;  that  nature  has  been 
iefirous  of  proving  that  the  terms  Deftrudion  and  Death  are 
relative  only  to  theimperfeftion  of  our  fenfes  ;  and  that  (he  is 
•never  more  fruitful  than  when  we  iuppofe  her  ;to  be  at  the  mo- 
/nent  of  extin£lion. 

The  fpoils  of  animals  which  live  on  the  furface  of  the  globe^ 
are  entitled  to  fome  ccnfideration  among  the  number  of  caufes 
•which  we  affign  to  explain  the  various  changes  our  planet  is 
fubjected  to.  *  We  find  bones  in  a  ftate  of -confiderable  preferva- 
tion  in  certain  places  ;  we  can  even  frequently  enough  diflin- 
guifh  the  fpecies  of  the  animals  to  which  they  h^ve  belonged. 
From  indications  of  this  fort  it  is  that  fome  writers  have  en- 
deavoured to  explain  the  difappearance  of  certain  fpecies  ;  and 
to  draw  conclulions  from  thence,  either  that  our  planet  is  per- 
/ceptibly  cooled,  or  that  a  fenfible  change  has  taken  place  in  the 
pjQijtion  of  the  axis  of  the  earth.  The  phofphorick  falts  and 
phofphorus  which  have  beenfofead,  in  our  time,  in  combination 
with  lead,  iron,  &c.  prove  that,  in  proportion  as  the  principle 
are  difengaged  by  animal  decompofition,  they  combine  with  othr 
.er  bodies,  and  form  the  nitrick  acid,  the  alkali3,  and  in  ge-uer^, 
fihe  numerous  kinds  of  nitrous  falts. 


PART  THE  THIRD 

CONCERNING  METALLICK  SUBSTANCES. 


INTRODUCTION. 


iMeTALLICK  fubftances  are  diftinguifhed  from  all 
{ht  other  produ£tions  of  our  globe,  by  an  abfolute  opacity,  a 
ihuch  greater  fpecifick  gravity  than  that  of  any  other  fubftancCy 
and  a  degree  of  brilliancy  peculiar  to  bodies  of  this  clafs. 

The  multiplicity  of  ufes  to  which  metals  are  applied  in  the 
arts,;  and  in  medicine,  as  well  as  the  place  which  they  occupy 
in  the  natural  hiftory  of  our  planet,  render  the  ftudy  of  thenr 
both  intereftirig  and  neceflary. 

I.  One  of  the  diftinclive  charadlers  of  metals  is  their  opacity. 
The  moft  opaque  (lone,  divided  into  very  thin  Jaminie,  becomes 
franfparent  *,  whereas  the  thinneft  plate  of  metal  preferves  the 
fame  opacity  as  the  mafs  itfelf."^  This  truly  charafterilUck  pro- 
perty has  induced  artifts  to  employ  metals  to  reflect  the  images 
ofobje£ls.  A  thin  covering  of  tin  and  mercury  fixed  on  the 
furface  of  a  glafs,  forms  a  mirror  or  looking-glafs  ;  and  well 
polifhed  fteel  conftitutes  the  mirrors  of  telefcopesf  The  hard* 
nefs  of  a  metal  contributes  fingularly  to  facilitate  the  refle<51ion 
of  objedls,  as  it  renders  it  capable  of  taking  a  very  fine  polilh, 

*  Gold  excepted  :  whichj  when  beaten  into  leaf  of  about  the  two  hun- 
dred and  eighty  thoufanddi  part  of  an  inch  in  thicknds,  tranfmits  light 
of  a-  beautiful  green  colour.  It  is  highly  probable  that  other  metals- 
would  become  tranfparent  if  they  could  be  mechanically  divided,  or 
beaten  out  into  laminae  of  fufficient  thinnefs,  or  if  artiits  had  fulficient 
motives  to  attempt  it. 

See  Newton  on  Light  and  Colours,  for  the  proofs  on  which  he  ground* 
His  generalinference — that  all  bodies  are  traniparent  when  fuiiiciently  di- 
vided.   T. 

f  I  do  not  find  that  fteel  has  ever  been  in  general  ufe  for  reflecTting  tel- 
efcopes,  though  it  has  doubtlefs  been  tried  among  the  many  expe- 
riments made  for  the  improvement  oi  thefe  inllrunients.  A  kind  of 
bell-metal,  confilling  of  one  third  tin,  and  two  thirds  copper,  is  com- 
monly employed  for  this  purpoie  :  the  addition  of  about  a  fiftieth  part  of 
arfenick  fingularly  contributes  to  the  clofenefs  of  its  grain.  On  this  fubjeft 
confult  the  Treatife  of  Mr.  Edwanls,  annexed  to  the  Nautical  Almanack- 
for  178-7.    T.  ". 


272  Genera!  Properties  of 

but  its  colour  ma'l  necefiarily  concur  to  render  It  perfe£t  ; 
for  thefe  tinges  caufe  it  to  abiorb  a  greater  or  lefs  quantity  of 
the  rays.  The  great  defect  of  metaliick  mirrors  is,  that  their 
furface  becomes  tarnhlied  by  the  inevitable  alteration  which  the 
action  of  the  air  and  moifhire  mu(l  produce. 

2.  The  relative  weight  is  likewife  a  character  by  which  we 
may  diftinguifli  a  metaUick  fubftance.  A  cubick  foot  (French) 
of  marble  weighs  190  pounds  (livres) ;  a  cubick  foot  of  tin 
weighs  510;  and  a  cubick  foot  of  gold  1348. 

The  metals,  in  general,  likewife  poflefs  the  facility  of  being 
extended  and  flattened  when  ftruck,  or  fubjetted  to  a  ftrong 
and  gradual  prelUire  :  this  property  Is  known  by  the  name  of 
Daclility.  All  the  metals  do  notpofiefs  this  quality  ;  but  thofe 
ivhich  poffefs  the  metaliick  qualities  moft  eminently,  exhibit  this 
likewife.  We  may  diftinguifh  three  (lates  of  duclility  relative 
to  the  manner  In  which  it  is  modified  by  various  known  procef- 
les.  1.  Ductility  under  the  hammer.  2.  DucSliiity  through 
the  plate  of  the  wire-drawer.  3.  Duclihty  between  the  lami- 
nating rollers. 

Metals  duiflile  under  the  hammer  prefent  themfelves  in  the 
following  order  :  Gold,  Silver,  Copper,  Iron,  Tin,  and  Lead. 

Metals  duclile  through  the  wire-drawer's  plate  form  the  fol- 
lowing feries  :  Gold,  Iron,  Copper,  Silver,  Tin,  and  Lead. — As, 
in  the  operation  of  wire-drawing,  the  metal  is  ftrongly  drawn, 
to  caufe  it  to  pafs  through  holes  of  various  diameters,  and  to  re- 
duce it  into  threads,  the  metals  do  not  refift  this  prodigious  ex- 
tenfion  but  in  proportion  to  their  greater  or  lefs  tenacity.  Mr. 
I)e  Fourcroy  has  therefore  dirtinguiHied  this  ductility  from  the 
foregoing,  by  attributing  it  merely  to  the  tenacity  of  the  metals. 

There  are  fome  metals  which  are  not  duttile  either  under  the 
hammer  or  through  the  wire-drawer's  plate,  but  become  very 
ronfiderably  ^o  when  an  equal  and  gradual  preffure  is  applied. 
Zinck  is  of  this  nature.  Mr.  Sage  has  reduced  it  into  very  thin 
and  very  flexible  leaves,  by  paffing  it  between  the  laminating  cy- 
linders. 

Heat  afiafls  the  duclillty  of  all  metals,  by  feparating  their  in- 
tegrant parts,  and  forming  fpaces  or  interfl:ices  which  permit  the 
comprefled  molecules  to  flatten  and  extend  themfelves.  This  cir- 
cumllance  has  induced  artiils  to  avail  themfelves  of  the  affiilance 
of  heat  in  the  working  of  metals.  Without  this  precaution 
they  would  cither  become  hard,  or  crack  ;  becaufe  the  particles, 
being  too  near  each  other  would  be  no  longer  capable  of  givirig 
way  under  the  hammer. 

The  ductility  of  metals  permits  us  to  faQiion  them  as  we  think 
fit ;  and  it  is  upon  this  admirable  property  that  almott  all  the 


Metal  lick  ^ubflances,  ty^ 

ans  are  founded  which  relate  to  the  working  of  metals.  With- 
out this  property,  metallick  bodies  would  confill  cither  of  fhape* 
lefs  mafles,  or  large  pieces  of  fuch  figures  as  cafting  might  pro* 
duce.  But  we  fhould  be  deprived  of  the  number  of  various  ob- 
jects which  the  arts  have  fucceffively  afforded  to  fupply  our  wants 
Or  luxuries. 

Nature  very  feldom  prefents  us  with  metals  pofTefTed  of  the 
degrees  of  perfection  here  enumerated.  She  has  concealed  them 
in  the  bowels  of  the  earth,  combined  with  various  fubftances ; 
which,  by  mafking  or  chariging  the  metallick  properties,  have 
left  to  the  induftry  of  man  the  laborious  tafk  of  extracting  them, 
clearing  them  of  their  original  combinations,  and  giving  them  the 
valuable  qualities  which  are  peculiar  to  metals.  The  metals, 
thus  buried  and  concealed,  form  ores.  Thefe  ores  ufually  exift 
in  clefts  or  crevices  of  rocks,  which  are  diftinguifhed  by  the 
name  of  Veins.  Thefe  veins  are  more  or  lefs  inclined  to  the 
horizon  ;  and  the  degrees  of  inclination  have  caufed  them  to  be 
diftinguifhed  by  the  names  of  direct,  oblique,  inclined,  or  level 
veins,  according  to  the  angle  they  make  with  the  horizon.  The 
part  of  the  rock  which  refts  upon  the  fuperiour  part  of  the  vein, 
is  called  the  Roof  ;  and  that  part  upon  which  the  vein  itfelf  refts, 
is  called  the  Bed  of  the  vein.  Thefe  veins  are  of  various 
breadths,  and  are  accordingly  diftinguifhed  by  the  names  of 
Slips  of  Veins. 

They  pofTefs  a  greater  or  lefs  degree  of  continuity,  according 
to  which  they  are  diftinguifhed  by  the  names  of  continued  or 
broken  veins  ;  and  when  the  ore  is  found  in  fpherical  parts  or 
mafTes,  from  fpace  to  fpace,  thefe  mafles  are  called  Bellies  or 
Stock-works.  A  vein  which  does  not  penetrate  to  a  confiderabb 
depth  in  the  earth,  is  called  by  us  Goureur  de  Gazon. 

The  characters  from  which  mineralogifts  pretend  to  alTert: 
the  exiftence  of  an  ore  in  the  bowels  of  the  earth,  are  all  equiv- 
ocal and  fufpicious.  The  favage  afpedl  of  a  mountain,  the  na- 
ture of  the  plants  which  grow  upon  it,  the  exhalations  which 
arife  from  the  earth,  all  aflbrd  characters  too  doubtful  for  a  rea- 
fonable  man  to  rifk  his  fortune  upon  fuch  indications  alone. 
Tiie  dipping  wand,  or  divining  rod,  is  the  fruit  of  fuperftition 
and  ignorance ;  and  the  ridicule  which  has  been  fuccefhvely 
thrown  upon  this  clafs  of  impoftors,  has  diminilhed  their  num- 
h^x ;  at  the  fame  time  that  the  numerous  dupes  of  this  clafs  of 
men  have  rendered  their  fucceflbrs  more  prudent 

The  nature  of  the  ftones  which  compofe  a  mountain  is  capa- 
ble of   furjiidiing  fome  indications.       We  know,    for  example, 
that  ores    are  feldom  found  in  granite,  and  the  other  primitive 
mountains  j  we  know  llkewife  that  mountains  of  toa  modera  a 
2...L 


2^74  Mines  and  Mdallich  Ores. 

formation  contain  them  very  rarely  5  and  we  find  them  only  in' 
fecondary  mountains,  in  which  the  fchiitus  and  ancient  calcare- 
ous ftone  are  void  of  all  impreffions  of  (hells. 

The  prefence  of  ponderous  fjjar,  forming  a  ftratum  or  vein  at 
the  furface  of  the  earthj  has  been  confidered  by  many  mineral- 
Ggifts  as  a  very  good  indication.  It  appears  to  me  even  that  this 
ftone  is  the  fame  which  Becher  has  fpoken  of  in  his  works,  un- 
der the  name  of  Vitrifiable  Earth,  which  he  confidered  as  a  prin- 
ciple of  metals ;  and  that  it  has  been  very  improperly  taken 
for  quartz  by  his  readers. 

The  vitrifiable  ftone  of  Becher — <«  lapidis  fpecies  quae  in  igne 
lluit,  et  fluens  vitrum  exhibet," — and  elfewhere,  «<  tranfparens^ 
enim  nonnihil  eft;  albus,  et  quafi,  argenteis  foUis  interfperfus, 
ad  ignem  facile  liquabiiis," — was  confidered  by  him  as  a  certain 
indication  of  the  prefence  of  ores,  as  appears  by  the  following 
paflTage  :  "  Sine  quo  lapide,  nulla  minera  bona  eft,  nee  fertilatem 
promittit ;  adeo  enim  ifte  lapis  mineris  neceflarius  eft,  ut  vel 
nude,  et  fine  uUo  mctallo,  in  montibus  exiftens,  infallible  fignum 
futuri  metalli  fit ;  quod,  hoc  figno  freti,  non  fine  magnis,  inter- 
dum  fumptibus,  qujerunt  minerarum  indagatores  ;  hanc  ergo 
five  terram  five  lapidem,  non  fine  pregnatibas  caufis,  pro  princi- 
pioprimo  omnium  metallorum,  minerarum,  et  lapidum  ac  gem- 
marum,  ftatuimus  et  agnofcimus  ;  certis  freti  experimentis,  ut 
in  fequentibus  demonftrabimus,  quibus  evincere  poflumus  prx- 
fatam  terram  a£lu  in  metallis  et  mineralibus  omnibus,  nee  non 
lapidibus  et  gemmis,  exiftere,  eorumque  mixtum  ut  bafim  et  fun- 
damentum  ingredi  \  unde  ea  hypoftafin  fuam,  oppofitatem,  dia- 

phaneitatem,  et  fluxum  nancifcuntur Haec  ergo  terra  non 

niodo  cum  prefens  adeft  infallibile  fignum  aft'uturi  metalH  eft,  {t6, 
et  abfens  idem  fignum  exiftit,  defuturi  nempe  metalli de- 
fect us  hujus  terrje  proxima  et  frequentiflima  caufa  fteriliuni 
ininerarum  exiftit ....  lapis  de  quo  egimus,  non  modo  ut  matrix 
fed  ut  ingrediens  ct  principium." 

When  wepoflefs  indications  of  the  exiftence  of  an  ore  in  any 
place,  we  may  ufe  the  borer,  to  confirm  or  dcftroy  thefe  fuf- 
picions,  at  a  fmall  expenfe. 

It  frequently  happens  that  the  veins  are  naked  or  uncovered  ; 
the  mixture  of  ftones  and  metals  forms  a  kind  of  cement  which 
refifts  the  deftrudlive  adion  of  time  longer  than  the  reft  of  the 
mountain  ;  and  as  thefe  parts  of  rocks  conncdled  by  a  metallick 
cement,  prefent  a  ftronger  refiftance  to  the  adtion  of  waters, 
which  inceflantly  corrode  and  diminifh  mountains,  and  carry 
away  their  parts  into  the  fea,  we  frequently  obferve  the  veins 
projecting  on  the  fides  of  the  mountains  incrufted  with  fome^" 
flight  metallick  impreflion  altered  by  the  lapfe  of  time. 


The  JJfaying  sf 'Ores.  275 

Before  we  proceed  to  treat  of  metallick  works  In  the  large 
way,  it  will  be  proper  to  explain  the  methods  of  judging  of  the 
nature  and  value  of  an  ore,  in  order  that  the.  members  of  fo- 
ciety  may  not  raflily  hazard  their  fortunes.  The  nature  of  an 
ore  is  judged  from  infpe<ftion.  A  flight  acquaintance  with  this 
fubje6t  is  fufficient  to  enable  the  obferver  to  form  an  immediate 
judgment  of  the  nature  of  an  ore.  The  blow-pipe  is  an  inflru- 
ment  by  the  afTiftance  of  which  we  may  in  a  (hort  fpace  of  time 
become  acquainted  like  wife  with  the  fpecies  of  the  ore.  This 
knowledge  forms  thedocimaftick  art,  or  docimafia.  In  order 
to  make  the  aflay  of  an  ore,  in  general,  (for  all  ores  do  not  re- 
quire the  fame  procefs,  as  we  Ihall  hereafter  obferve,)  fmall  pie- 
ces of  the  mineral  are  examined.  Thefe  are  cleared  from  for- 
eign and  flony  fubftances  as  much  as  poflible.  The  pure  min- 
eral is  then  pounded,  and  a  certain  quantity  weighed,  which  is 
torrefied  in  a  veiTel  larger  and  lefs  deep  than  a  common  crucible. 
By  this  means  the  fulphur  or  the  arfenick  in  combination  with 
the  metal  are  dilTipated  ;  and  by  the  Jofs  of  weight  refulting 
from  the  calcination,  a  judgment  is  formed  of  the  proportion 
of  foreign  volatile  matter  it  contained. 

This  firft  operation  {hews  the  proportion  and  quantity  of  ful- 
.phur  and  arfenick  which  may  be  mixed  with  the  metal.  The 
fulphureous  fmell  may  eafily  be  didinguifhed  from  the  fmell  of 
garhck,  which  characterizes  arfenick.  T-hefe  foreign  fubftan- 
-ces  mixed  with  the  metal  are  called  Mineralizers. 

In  order  to  obtain  an  accurate  judgment  of  the  weight  of  the 
mineralizer,  the  augmentation  in  weight  which  the  metal  has 
undergone  in  pafling  from  its  metallick  ftate  to  that  of  oxide  or 
calx,  muft  be  added  to  the  lofs  occafioned  by  the  calcination. 

Two  hundred  grains  of  this  roafted  ore  are  then  to  be  taken, 
and  mixed  with  fluxes  capable  of  fufing  and  reducing  it.  In 
this  operation  a  crucible  is  made  ufe  of;  and  a  fuflicient  degree 
of  heat  being  applied,  the  nietal  is  precipitated  to  the  bottom  of 
the  crucible  in  a  buttoji,  whofe  weight  indicates  the  quantity  of 
metal  contained  in  the  ore. 

Thefe  fluxes  muft  be  varied  according  to  the  nature  of  the 
;,ores  under  examination.  It  is  neceflary  that  they  {hould  all 
contain  the  coaly  principle,  to  difengage  the  oxigene  with  which 
4:hefe  metals  are  impregnated  by  the  calcination.  But  the  na- 
ture of  the  flux  muft  be  varied  according  to  the  fufibility  of  the 
metal.     The  three  following  will  anfwer  all  thefe  purpoles. 

I.  The  fufible  material  called  black  flux  is  made  with  two 
parts  of  tartar,  and  one  part  of  nitre  melted  together.  TJie  coaly 
and  alkaline  refidue  is  ufed  to  reduce  the  ores  of  lead,  copper, 
sntimony,  &c. 


?7^  W^^^^^g  of  M'tnes. 

2.  Two  hundred  grains  of  calcined  borax,  and  one  hundred 
grains  of  nitre,  twenty  grains  of  flacked  lime,  and  one  hundred 
grains  of  the  ore  Intended  to  be  affkyed,  form  the  flux  of  fcopoli, 
of  which  I  have  found  the  advantage  in  the  aflay  of  iron  ores. 

The  vitreous  flux  of  Mr.  De  Morveau,  made  with  eight  parts 
of  pounded  glafs,  one  of  borax,  and  half  a  part  of  powder  of 
charcoal,  may  be  employed  for  the  fame  purpofe. 

3.  Arfenick  and  nitre,  in  equal  parts  form  likcNvife  a  yery 
a£live  flux. 

The  neutral  arfenical  fait  has  been  ufed  with  fuccefs  to  fufe 
platina. 

As  foon  as  the  exiflence  of  a  mine,  and  its  nature  and  riches 
?ire  afcertained,  it  is  in  the  next  place  neceiiary  to  be  aflTured  of 
a  fufl&cient  abundance  and  continuity  of  water  to  anfwer  the 
purpofes  of  the  works.  It  is  likewife  necefiary  to  be  aflured  of 
pofieflTmg  a  fufficient  quantity  of  wood  or  charcoal ;  and  more 
efpecially,  a  good  director  muftbe  procured  :  for,  in  my  opin- 
ion, a  poor  mine  well  managed  is  preferable  to  a  rich  one  ill  con- 
duaed. 

Thefe  preliminary  circumftances  being  accompli{lied,the  moPt 
fimple  and  lead  expenfive  procefles  muft  be  employed  In  extrac- 
ting the  mineral  from  the  bowels  of  the  earth.  For  this  pur- 
pofe, ihafts  pr  galleries  muft  be  dug,  accordjrig  to  the  pofition 
of  the  vein,  and  the  nature  of  its  fituation. 

When  it  is  pra£licable  to  arrive  at  the  fide  of  the  vein,  and  ^t 
a  certain  depth,  by  a  horizontal  gaUery,  the  works  become  more 
fimple  and  economical  ;  the  fame  opening  ferylng  to  draw  off 
jLhe  waters,  and  extract  the  ore.  Galleries  are  then  to  be  carried 
on  to  the  right  and  left  ;  and  iliafts  funk,  which  communicate 
with  the  open  air,  as  likewife  others  carried  down  into  the  vein. 
Galleries  are  likewife  conftru£ted,  one  above  the  other,  and  th^ 
communication  of  the  works  kept  up  by  ladders.  When  the 
foil  is  friable,  and  defetlive  in  folidity,  care  muft  be  taken  to 
fupport  it  with  timbers  of  fufl^clent  ftrength,  to  prevent  its  fall- 
ing in. 

Pickaxes,  wedges,  and  levers  are  ufed  to  detach  the  ore, 
when  the  rock  is  foft  ;  but  it  is  moft  commonly  neceflary  ts) 
employ  gunpowder,  and  to  form  mines. 

Want  of  air,  and  the  abundance  of  water,  arc  almoft  always 
noxious,  and  derange  mine  works.  The  water  is  carried  off  by 
ftre-engincs,  wind-mill  pumps,  and  other  fuitable  apparatus. 

Currents  of  air  are  produced  by  eftabliftiing  communications 
with  the  galleries  by  horziontal  apertures.  Furnaces  ereded 
on  the  fide  of  a  (liaft,  to  which  a  long  tube  is  adapted  at  ouv? 
end,  communicating  with  the  afli  hole,  and  at  the  other  plung- 


Working  of  Mines,  277 

iiig  into  the  fliaft  to  draw  up  the  air,  or  ventilators  placed  in  the 
fame  fituation,  aniwer  a  fimilar  purpofe.  The  foul  air  is  de- 
ft royed  by  rendering  a  lixivium  ot  aihes  cauitick  ;  and  I'prinkling 
quick-hme  about  ihe  mine  likewile  produces  the  Hmie  et^e^l. 

A  prudent  company  ought  to  extract  the  larged:  pofiible  quan- 
tity of  ore,  before  they  detqrniine  upon  conltrudiisg  the  necefia- 
ry  woiks  for  the  fubfequent  procefles.  We  cannot  fee  into  the 
bowels  of  the  earth.  Appearances  are  often  deceitful  ;  and  wc 
havefecn  companies  either  ruined  or  difcouraged,  becaufe  they 
had  employed  immenfe  fums  to  conftrutl  the  neceilary  furnaces 
to  work  an  ore  whofe  exiftence  was  doubtful.  When  the  pro- 
f:eedings,  in  an  undertaking  of  this  kind,  are  carried  on  with 
proper  precaution,  and  no  more  expenfe  is  entered  into  than 
what  the  ore  extracled,  and  of  a  known  value,  is  capable  of  rep- 
refenting,  the  probable  Ipiles  are  very  flight,  even  in  the  poorefl: 
niine. 

The  works  ought  to  be  varied  according  to  the  nature  and 
{late  of  the  mineral.  It  is  found  in  three  dates — i.  In  the  form 
of  a  native  metal  :  in  this  cafe  nothing  more  is  neceflary  than 
to  extra^  it  out  of  the  mine,  to  clear  it  of  the  extraneous  lub- 
ilances,  and  to  fuf^  it.  %.  In  the  form  of  calx  or  oxide  ;  and 
in  this  ftate  it  isfuflicient  if  it  be  forted  and  fufed.  3.  Combine 
ed  with  fulphur  or  arfenick,  jn  which  cafe  it  muft  be  made  to 
undergo  fome  other  operations. 

Although  in  this  lalt  cafe,  the  works,  fubfequent  to  the  extrac- 
tion, vary  according  to  the  nature  of  the  ore,  there  are  never- 
thelefs  certain  general  operations,  to  which  every  kind  <  f  ore  is 
fubjedted,  which  we  (hall  here  fpeak  of. 

The  metal  is  always  mixed  with  ftony  fubftances,  which  are 
called  the  Gan^ue.  The  firit  bufinefs  muft  therefore  be  to  clear 
the  metal  of  this  foreign  fubftance.  For  this  purpofe,  when 
the  ore  is  extra6led,  children  are  employed  who  examine  it,  and 
feparate  the  pure  ore  or  rich  mineral  from  that  which  is  mixed 
with  the  gangue.  As  in  this  fecond  quality  the  ftone  is  mixed 
with  the  ore,  the  whole  is  pulverized  by  means  of  a  damping 
mill,  confifting  of  pelHes  of  wood,  fliod  with  iron,  and  armed 
with  cocks,  which  are  raifed  by  levers  proceeding  from  the  axis 
of  a  wheel  that  conftantly  returns.  The  mineral  is  by  this 
means  crufiied  and  pulverized  ;  and  a  flream  of  water  which  is 
made  to  pafs  over  it,  carries  away  both  the  metallick  and  llony 
particles  -,  the  former  being  depofited  in  the  firft  velFels  through 
wjiich  the  water  is  made  to  circulate,  while  the  latter  or  ftony 
part  is  carried  to  a  greater  diftance  on  account  of  its  lightnefs. 
This  pulverized  ore  is  called  Sclich  ;  and,  in  order  to  feparate 
a|i   t,he  earthy  parts,  it  is  ^vaflled  upon  tables  flightly  inclined, 


2/8  Bloiving  Machines. 

over  which  a  conflant  ftream  of  water  is  made  to  flow.  The 
fciich  is  agitated  with  brooms  ;  the  water  carries  away  all  the 
fragments  of  ftone,  and  leaves  the  pure  ore  upon  the  table. 

The  calcination  of  the  mineral  fucceeds  the  wafliing.  In  this 
.operation  the  mineralizer  is  carried  off.  Fire  is  always  the  agent 
made  ufc  of.  Sometimes  the  pounded  mineral  is  difpofed  in 
piles  upon  heaps  of  wood,  which,  being  fet  on  fire,  heat  the 
ore  ftrongly,  and  drive  off  the  mineralizer.  This  calcinatioii 
jxjirefles  the  double  jidvantage  of  difpofmg  the  metal  for  fufion, 
as  well  as  clearing  it  of  the  minerahzing  fubllance.  When  the 
ore  is  more  friable  it  is  fpread  out  in  a  reverheratory  furnaCe^ 
and  the  flame  which  reverberates  upon  it  deprives  it  of  its  min- 
eralizer, at  the  fame  time  that  it  partly  fufes  it. 

Mr.  Exchaquet  has  propofed  to  deftroy  the  fulphur  by  nitre. 
This  procefs  is  excellent  for  copper  ores.  The  quantity  of  nitre 
varies  according  to  the  quantity  of  fulphur  ;  but  there  is  no  dan- 
ger of  adding  too  much.  In  this  operation  the  mixture  is 
thrown  into  an  ignited  crucible,  and  kept  at  a  moderate  heat  for 
fome  minutes. 

The  fufion  is  effe£ted  in  fu.rnaces,  excited  by  a  current  of  air, 
kept  up  by  means  of  large  bellows,  or  a  machine  called  a 
ircmpe. 

The  trompe,or  blowing  machine,*  is  formed  of  a  hollow  tr6e 
which  refts  upon  a  cafic  whofe  lower  hetid  is  knocked  out,  and 
the  open  part  of  the  cafk  itfelf  plunged  to  a  certain  depth  un- 
der water.  A  current  of  water  is  made  to  fall  through  this 
■wooden  trunk  upon  a  flone  which  is  ereifled  in  the  middle  of  the 
calk.  The  air  becomes  difengaged,  and  is  obliged  to  pafs  out  at 
a  collateral  aperture  in  the  cafk,  by  means  of  a  tube  which 
carries  it  to  the  lower  part  of  the  furnace.  This  air  is  afforded 
—  I.  By  that  air  which  the  water  carries  along  with  it.  2.  By 
a  current  which  pafTcs  through  apertures  made  at  the  diflance 
of  fix  feet  from  the  fummit  of  the  tree,  and  called  trompilles. 

The  dimenfions  of  a  good  trompe  are  the  following  : 

Length  of  the  tree  or  wooden  trunk,  from  its  fummit  to  the 
fide  apertures  or  trompilles,  fix  feet. 

Length  of  the  tree  from  the  trompilles  to  the  calk,  eighteen 
feet. 

Height  of  the  calk,  five  feet. 

Diameter  of  the  cafit,  four  feet  fix  inches* 

*  I  do  not  find  in  Lewis's  Commerce  of  Arts,  where  this  fubje<5t  h 
well  treated,  that  the  Englilh  havf  called  this  machine  by  any  appropn- 
^ted  name.    T. 


Properties  of  Metatr,  279 

iThe  form  of  the  Internal  part  of  the  trunk  above  the  trom- 
pllles,  is  that  of  a  funnel,  whofe  fuperiour  opening  is  eighteen 
inches,  and  its  inferiour  diameter  five. 

The  diameter  of  the  cavity  of  the  tree,  below  the  trompilles> 
h  eighteen  inches. 

The  diameter  of  the  trompillesis  fix  inches. 
The  (tone  upon  which  the  waterfalls  is  eighteen  inches  in  di- 
ameter. 

When  the  mineral  is  once  cleared  of  its  gangue,  its  mineral- 
rzer,  and  all  other  foreign  matter,  it  conftitutes  what  is  called  a 
metal,  or  regulus.- 

Every  facS  appears  to  prove  that  metals  are  fimple  fubftances  j- 
the  various  alterations  to  which  they  are  fubjedled,  being  combi- 
nations of  the  metal  itfelf  with  other  fubitances.  None  of  thefe 
operations  either  difengage  or  feparate  any  conftituent  part  of  the 
metal  itfelf,  as  we  fhall  fee. 

Every  metal  is  fufed  at  a  certain  deg^ree  of  heat,  more  or  lefs 
inrenfe  ;  and  in  this  fituation  their  furface  is  convex. 

Meflrs.  MacqjLier  and  Lavoifier  having  expofed  gold  to  the  fo- 
cus of  the  lens  of  Tfchlrnhaufen,  obferved  that  this  metal  exhal- 
ed in  fumes,  without  being  decompofed  ;  as  v/as  proved  by  col- 
lecting it  unaltered  upon  prefenting  a  plate  of  filver,  which  be- 
came gilt.  Silver  is  volatilized  in  the  fame  manner  without 
decompofition. 

Metals  fufed^and  cooled  flowly,  exhibit  cryfliallizations  of  con- 
fiderable  regularity.  The  abbe  Mongez,  and  Mr.  Brogniart, 
have  fucceededin  cryflallizing  mofl  of  them,  by  varying  the 
proccfs  ufed  by  the  celebrated  Roulle  in  the  cryftallization  of 
fulphur. 

•  Mod  metals  kept  in  a  ftate  of  fufion  lofe  their  metallick  bril- 
liancy, and  become  converted  into  an  opaque  povrder  called  Ox- 
ide, or  Metallick  Galx.  The  oxides,  when  urged  by  a  (ironger 
heat,  arc  reduced  into  a  vltriform  fubdance,  known  bv  the  name 
of  Metallick  Glafs. 

Metals  acquire  weight  in  their  tranfiticn  to  the  ftatc  of  oxide. 
This  circumftance  has  led  feveral  adepts  into  errour,  who  im- 
'.igined  they  had  increafed  the  weight  of  the  metal. 

Geber  ooiervcs,  <*  Ubi  vel  minimum  augmenti  metallici  in- 
veneris,  ibi  te  decimus  efie  ante  fores  philofophorum." — «  Et 
fane  conveniens  judicium  elt,"  adds  Bccher  ;  <*  idenim  per  quod' 
corpus  homogeneuni  augmcntum  capit,  id  ipfiim  eft  quod  pro 
priucipio  ilfius  corporis  haberi  potell."- — Phyf.  Subt. 

Stahl  pretended  that  the  calcination  of  metals  arofe  from  the 
difengagement  of  phlogidon  5  and- he  confidered  their  calces  as 
an  eatth,  or  metallick  bafio. 


2-8  o  Proper  tics  of  Meials, 

Boyle  affirmed  that  the  lacreafe  of  weight  in  calcined  metals 
was  owinp;  to  the  combination  of  matter  of  fire  j  and  Boerhaave 
ventured  to  attribute  it  to  the  furrounding  bodies,  which  dcpofit- 
ed  themfelves  upon  the  meral.  Of  all  the  hypothefes  which 
haA-e  been  formed  upon  this  fubject,  that  of  Stahl  has  raet  with 
the  greateft  number  of  fupporters  :  and  the  blind  zeal  of  his  fol. 
lowers  hns  carried  them  fo  far  as  even  to  difguife  an  unanfwera- 
ble  obje(Stion  ;  namely,  that  it  can  never  be  explained  how  met- 
als, by  the  lofs  of  one  principle,  at  the  fame  time  that  they  do 
not  acquire  another,  can  become  heavier.  The  redudion  of 
the  oxides  or  metallick  calces,  without  any  addition  of  the  char- 
coal, cannot  be  explained  on  this  hypothefis. 

It  mud  be  confefled  that  all  chemiiis  were  not  of  this  way  of 
thmkmg :  and  we  find  in  the  writings  of  Jean  Rey,  a  Phyfician 
of  Pengcrd,  that  he,  in  the  year  1630,  attributed  the  increafe 
of  v/eight  in  calcined  metals  to  the  combination  of  air  with  the 
metal.  He  aflirms  that  agitation  facilitates  this  combination  in 
no  other  manner  than  water  renders  the  fand  heavy  which  is 
thrown  and  agitated  in  that  fluid. 

He  reafons  like  a  chemiil  of  confiderable  fkill,  to  prove  that 
the  increafe  of  weight  cannot  be  carried  beyond  a  point  of  fatu- 
ration  ;  and  he  concludes  his  obfervations  in  thele  words:  Le 
tra'uail  a  eie  mien  ;  le  profit  en  foit  an  lecieur^  et  a  Dieu  feiil  la 
glo'trc — '*  Mine  has  been  the  labour  ; ,  let  the  reader  enjoy  the' 
advantage,  and  to  God  alone  be  the  glory."* 

All  thefe  fev«Tal  {ketches  were  never  formed  into  a  conne£led 
fyltem  5  and  this  doclrine  was  even  completely  unknown,  when 
Mr.  Lavoifier  proved  to  us  th?t  the  calcination  of  metals  was 
owing  merely  to  the  fixation  of  oxigenous  gas,  and  their  reduc- 
tion to  the  difengagement  of  this  gas,  eiFe£\ed  by  fimple  heat,  or 
by  its  combin.itlon  with  various  bales  in  fuch  inftances  whercirt 
its  adhefion  to  the  metal  is  too  ftrong  to  be  overcome  by  mere 
heat.  The  proofs  upon  which  this  celebrated  chemifl:  has  eftab- 
liflied  \\\'i:  opinion,  are  the  following  facfts. 

I.  Metals  are  not  oxided  either  in  a  vacuum,  or  in  air  which 
contains  no  part  of  oxigenous  gas.  The  Count  Mo^ozzo,  Priefl;- 
ley,  Lametherie,  and  Piglet  appear  to  have  oxided  lead,  tin,  and 
fiiercury  in  the  carhi^nick  acid.  See  the  Memoir  of  Mr.  Sennc- 
l>ier.  Journal  de  Phvfique,  Fevrier,  1787. — But  this  pretended 
cxide  is  nothing  but  a  mctallick  carbonate,   or  the  combinatiork 

*  This  13  the  fame  Jean  R'V'  u-ho,  beinp;  under  the  necefiity  of  contra- 
cii:'r"ng  his  friend  Likivin:- on  the  theory  of  the  calcination  of  metals,  ex- 
claims— "  O  tnith,  hov/  ric^r  art  tliou  to  me  !  iince  it  is  in  thy  power  to 
make  me  cnicr  into  a  conieft  with  fc  dear  c  friend  " 


Properties  of  Metals,  281 

of  a  metal  with  an  acid,  which  is  very  far  from   calcination  or 
oxidation. 

2.  Metals  inclofed  under  a  glafs,  and  properly  heated,  are  ox- 
idcd  only  by  abforbing  the  oxigenous  gas  contained  in  the  mafs 
of  air  which  is  infulated  ;  and  when  this  abforption  is  ended,  it 
is  impoflible  to  carry  the  oxidation  any  further. 

3.  Metals  oxided  in  an  atmofphere  of  oxigenous  gas  abforb  it 
to  the  laft  drop. 

4.  Such  oxided  metals  as  are  capable  of  being  reduced  in  clo- 
fed  vcfTcly,  give  out,  on  their  return  to  the  metallick  ftate,  the 
fame  quantity  of  oxigenous  gas  as  they  had  before  abforbed. 

This  do£lrine  appears  to  me  to  be  eftablilhed  on  the  moft 
complete  feries  of  proofs  which  can  be  defired  in  matters  ca- 
pable of  demonftation. 

The  concurrence  of  air  and  of  humidity  finguiarly  afiifts  the 
alteration  of  metals.  The  water  is  decompofed  in  this  procefs, 
and  its  hydrogene  is  diffipated,  while  its  oxigene  combines  with 
the  metal.  This  is  doubtlefs  the  theory  of  fuch  oxidations  as  are 
effected  beneath  the  furface  of  water  ;  and  when  we  find 
oxides,  or  metallick  calces,  in  the  bowels  of  the  earth,  defended 
from  the  conta<fl:  of  air,  the  fadts  ought  to  be  referred  only  to 
the  decompofition  of  water,  or  of  acids  which  have  oxigene  for 
their  bafe. 

Hence  it  follows  that  the  alteration  of  a  metal  will  be  the 
more  fpeedy — i.  In  proportion  as  the  affinity  of  the  metal  to 
oxigenous  gas  is  ftronger.  2-  As  the  quantity  of  oxigenous  gas 
is  greater.  3.  As  the  air  is  more  humid,  &c.  Metals  decom- 
pofe  certain  fubftances  in  order  to  unite  with  their  oxigene,  and 
by  that  means  to  pafs  to  the  ilate  of  oxide.  This  is  obferva- 
ble  when  the  nitrick  acid  is  digefted  upon  certain  metals. 

Metallick  fubftances  being  confiderably  numerous,  it  is  necef- 
fary  to  clafs  them,  that  we  may  bring  together  fuch  as  pofTefs 
fimilar  properties,  and  feparate  others  which  differ  from  them. 

Ductility  ferves  as  a  leading  character.  Metals  may  be  dif- 
tinguifhed  into  fuch  as  are  du£tile,  and  fuch  as  do  not  poflefs 
this  property.  The  name  of  Metal  has  been  peculiarly  applied 
to  the  former,  and  that  of  Semi-Metal  to  the  latter  kind. 

Among  the  metals  there  are  fome  which  are  changeable  by 
expofure  to  air,  while  others  are  not  fenfibly  altered  in  the  fame 
fituation.  This  difference  has  caufed  a  fubdivifion  of  the  metals 
into  perfe<fl:  and  imperfect  metals. 

We  {hall  begin  by  treating   of  the  femi-metals,  becaufe  for 

the  moft  part  they  approach  to  the  faline  or    ftony  fubftances  in 

their  qualities  ;  and  we  ftiall  conclude  with  the  perfedl   metals, 

becaufe  they  pofiefs  the  metallick  qualities  in  a  higher   degree., 

2...M 


atS*  Arfimck* 

CHAPTER  I. 

Go-ncerning  Arfenlck* 

iTHE  fubftance  which  is  fold  in  commerGe  under  the  name- 
df  arfenick,  is  a  metallick  oxide  of  a  glittering  whitenels,  fome- 
timesof  a  vitreous  appearance  ;  exciting  an  impreffion  of  an  ac- 
rid tafte  on  the  tongue  5  volatile  when  expofed  to  fire,  in  vi^hich- 
fituation  it  rifes  in  the  form  of  a  white  fume,  with  a  very  evi- 
dent fmell  of  garlick. 

Although  arfenicfo is  mod  commonly  met  with  under  this  form^ 
it  may  be  reducedto  the  metallick  ftate  by  treating  it  with  oils, 
foaps,  or  charcoal  in  clofed  veffels.  The  celebrated  Becher  was 
perfectly  acquainted  with  this  procefs — «  Si  oleum,  vel  quod- 
ctanque  pitigue,  arfenico  mifceas,.  et  per  retortam  diitilles  urgen- 
ti  igne,  fublimabitur  in  collum  arfenicum,  infignitur  aiitimonii 
ihftar  metaHizatum."-^The  arfenick  which  fublimes  is  of  a  bril- 
liant grey  colour,  refembling  fteel,  but  it  fpeedily  becomes  black 
in  the  air  :  it  forms  cryftals,  which  Mr.  De  lifle  confiders  as 
uluminiform  o^ahedrons. 

Arfenick  is  fometimes  found  native;  and  it  is  met  with  in 
ftalaclites,  or  in  protuberant  depofitions  formed  of  layers  more 
or  lefs  diftin£l  and  concentrick,  which  are  feparable  from  each 
dtherlike  the  coats  of  an  onion,  or  the  laminsc  of  {hells,  from 
which  it  has  obtained  the  name  of  tellaceous  arfenick.  In  other 
inftances  the  malTes  are  formed  cf  very  fmall  fcales ;  which 
renders  the  furfacc  of  the  fpecimen  fometimes  granulated,  and 
fometimes  full  of  fmall  cavities  :  it  is  then  called- fcaly  arfenick. 
Arfenick  is  alfo  found  in  friable  maiies,  polTeffing  fcarcely  any 
donfiftence.  In  thefe  various  forms  we  receive  it  from  Bohemia,- 
Hungary,  Saxony,  Saint  Marie  aux  Mines,  &c. 

Arfenick  is  volatilized  by  an  heat  of  about  144  degrees  of 
Reaumur.  In  order  to  fet  fire  to  this  metal,  it  muii  be  thrown- 
ihto  a  crucible  flrongiy  ignited  ;  and  then  it  exhibits  a  blue  flame, 
and  rifes  in  the  form  of  a  white  oxide. 

If  it  be  fublimed  by  a  gentle  heat,  it  cryftallizes  in  trihedrar 
pyramids  or  in  octahedrons. 

Arfenick  is  not  foluble  in  water.  Its  fpecifick  gravity  is^ 
57633,  according  to  Brifibn.  Its  fraClure  refembies  that  of- 
iteel,  but  it  eafily  tarniihes. 

Arfenick  appears  to  exift  in  the  metallick  ftate  in  its  combi-" 
nations  with  cobalt  in  the  teltaceous  cobalt  are,  or  with  iroain' 
mifpickel,  according  to  the  obfervation  of  Bergmann* 


AricrJck  unites  by  fufion  with  rnqft  of  the  metals  5  but  thofe 
.•yrhich  were  duiSHle  before  this  addition,  become  brittle  after- 
wards. Thofe  which  are  of  difficult  fujion  alone  flow  mo;.e 
■eafily  by  heat  with  the  addition  of  arfeniek,  and  thofe  which 
^tre  very  fufible  become  refractory  by  the  fame  addition.  The 
yellow  or  red  metals  become  white  with  this  alloy. 

Arfeniek  is  often  combined  with  metals  in  various  ores,  arjd 
S3  difengaged  from  them  by  calcination.  In  various  mine  works, 
long  winding  chimneys  are  conftru^ted,  through  which  the 
?»rfenieal  vapours  pafs,  and  in  which  they  attach  themfelves. 
The  cruft  which  is  formed  in  procefs  of  time  againft  the  intern- 
al furface  of  thefc  chimneys  is  taken  away,  and  is  the  fubftance 
met  with  in  commerce  iinder  the  name  of  arfeniek.  The  co- 
balt ores  of  Saxony,  which  are  torrefied  to  feparate  this  fcmi- 
metal,  afford  almofl  the  whole  of  what  is  fold.  This  oxide  of 
Arfeniek  is  fometimes  native,  and  has.  been  found  in  Saxony  and 
Bohemia.  It  is  very  abundant,  infuch  places  as  are  fituated  in 
the  vicinity  of  fubterranean  fires,  fuch  as  the  Solfatara.  It  is 
often  found  cryftailized  in  o6lahedrona,  according  to  Mr.  Sage. 

The  oxide  is  lefs  volatite^han  the  metal  itfelf;  and,  as  we 
have  before  obferved,  it  ennits  a  very  evident  fmell  of  gariick. 
If  it  be  fublimed  by  a  ftrong  fire  in  clofed  yeflels,  it  becomes 
tranfparent  hke  glafs ;  but  its  furface  is  foon  rendered  opaque 
again  by  expofure  to  air.  It  is  not  rare  to  find  arfenical  glafs 
in  the  arfeniek  of  commerce  :  it, is  yellowifh,  and  fopn  lofes  its 
tranfparency  by  expofure  to  air.  This  glafs  is  fometimes  found 
native  in  the  cobalt  mines,  and  among  vo'canick  produ£ts. 

Eighty  parts  of  diftilled  water,  at  the  temperature  of  twelve 
degrees,  are  required  to  difiblve  one  part  of  the  oxide  of  arfen- 
iek ;  but  fifteen  are  fuffieient  at  the  boiling  heat. 

One  part  of  arfeniek  is  foluble  in  between  feventy  and  eighty 
parts  of  alcohol  at  the  boiling  heat. 

The  oxide  of  arfeniek  partakes  therefore,  of  the  properties  of 
faline  fubftances,  and  difiers  from  the  other  metallick  oxides-— 
I.  Becaufe  it  is  perfectly  foluble  iii  water.  2.  Bccaufe  the  oth- 
er metallick  oxides  are  without  fmell,  and  fixed  in  the  fire.  3. 
Becaufe  thofe  oxides  do  not  contract  any  union  with  metals. 

On  the  other  hand  it  refembles  the  metaiiick  oxides — i.  In 
becoming  converted  into  a  metallick  glafs  by  a  ftrong  heat.  2. 
In  forming  an  opaque  infoluble  fubftance,  poflefling  the  met^l- 
hck  brilliancy  when  deprived  of   oxigene. 

The  oxide  of  arfeniek  is  capable  of  combining  with  fulphur ; 
and  the  refult  is  either  orpiment  or  realgar,  according  to  |hc 
.manner  of  operating. 


284  JRjalgar.       Ofpiment. 

Moft  chenilfts  have  a  notion  that  the  realgar  contains  more 
fulphur  than  the  orpiment;  and  they  have  prefcribed  difFerem 
proportions  to  form  thefe  two  fuhftances.  Bat  it  has  been  prov- 
ed by  Mr.  Bucquet,  that  this  difference  of  colour  arifes  only 
from  the  manner  of  applying  the  fire  ;  nothing  more  being  ne- 
ceflary  to  convert  orpiment  into  realgar,  than  the  expofmg  it  to  a 
ftrong  heat :  and  with  the  fame  mixture  w€  may  at  pleafure  ob- 
tain either  of  thefe  produces,  according  to  the  manner  of  apply^ 
jng  the  heat. 

Orpim.ent  and  realgar  are  found  native  in  certain  places ;  Lin- 
naeus, Wallerius,  Bergmann,  and  Cronftedthave  defcribed  them. 

Cryftals  of  realgar  are  found  in  Solfatara  near  Naples,  accord- 
ing to  Ferber  ;  in  the  mines  of  Nagyag  in  Tranfylvania  (fee 
Forfter's  Catalogue  ;)  in  the  mines  of  Felfobanya  in  Upper  Hun- 
gary ;  in  thofe  of  Joachimftal  in  Bohemia,  and  of  Mari^nburg 
in  Saxony 

Realgar  is  common  in  China  ;  it  is  made  into  vafes,  pagods^ 
5ind  other  ornamental  works.  The  Indians  make  ufe  of  thefe 
veflels  to  procure  a  purgative  medicine :  for  this  purpofe  they 
leave  vinegar  or  lemon  juice  for  feveral  hours  in  the  veiTel,  and 
afterwards  drink  it 

Realgar  is  commonly  found  in  the  waters  of  volcanoes.  I  have 
almort  always  obferved  it  in  comprefled  hexahedral  prifms,  ter- 
minating in  two  tetrahedral  fumniits. 

Orpiment  is  lefs  fcarce  than  the  realgar.  It  almoil  always  ac- 
companies this  fubflance ;  but  the  orpiment  of  commerce  com.es 
to  us  from  various  countries  up  the  Levant,  in  irregular  maflcs, 
folid  or  lamellated,  and  of  a  beautiful  orange  yellow.  The 
Baron  de  Born  informs  us  that  it  is  met  with,  in  polyhedral  cryf- 
tals, in  a  bluiOi  clay  nearNewfoiin  Hungary. 

Lime  and  the  alkalis  decompofe  thefe  two  fubftances,  and 
difengage  the  oxide  of  avfenick. 

The  acids  and  the  alkalis  exhibit  interefting  phenomena  with 
arfenick. 

The  fulphurick  acid,  when  boiled  on  the  oxide  of  arfenick, 
attacks  and  difTolves  it  ;  but  this  oxide  is  precipitated  by  cool- 
ing. If  the  whole  of  the  acid  be  dillipated  by  a  (trong  heat,  the 
arfenical  acid  remains  behind. 

The  nitrick  acid,  alFifted  by  heat,  diffolves  the  oxide  of  arfen- 
ick,  and  forms  a  deHquefcent  fait,  of  wl«ch  v/e  fhall  prefently 
treat. 

The  muriatick  acid  attacks  arfenick  very  feebly.  MefTrs. 
Bayen  and  Char  lard  found  its  a  A  ion  very  weak  whether  heated; 
qr  cooled* 


Sublimed  Muriate^  atul  Ox'uk  of  Arfemck.  285 

In  order  to  form  the  fubllmcd  muriate  of  arfenick.  or  butter 
of  arfenick,  equal  parts  of  orpiment  and  corrofive  fublimate  of 
mercury  are  mixed  together.  Tlie  mixture  is  diftilled  by  a  gen- 
tle heat  ;  and  the  receiver  is  found  to  contain  a  blackifii  corro- 
five liquor,  which  forms  the  fublimed  muriate  of  arfenick.  Cin- 
nabar comes  over  if  the  heat  be  increafedj  according  to  the  ob- 
iei'vation  of  Mr.  Sage. 

If  pure  pot-afh  be  boiled  on  the  oxide  of  arfenick,  the  alkali 
becomes  brpwn,  gradually  thickens,  and  at  laft  forms  a  hard 
brittle  mafs.  This  arfenical  fait  of  Mr.  Macquer  is  deliquef- 
cent.  It  is  foluble  in  water,  which  lets  fall  brown  flocks.  It  is 
(decompofed  by  fire,  and  the  arfenick  eicapes.  Acids  deprive  it 
of  its  alkali,  &c. 

Soda  exhibits  phenomena  nearly  fimilar  with  this  oxide  ;  and 
Mr.  Macquer  even  affirms  that  he  obtained  this  fait  in  cryff  als. 

1  have  proved  that  ammoniack  diflblves  the  oxide  of  arfenick 
by  heat  j  and  I  have  feveral  times  obtained  cryftals  of  arfenick 
by  fpontaneous  evaporation.  I  am  even  of  opinion  that  the  al- 
kali is  decompofed  in  thefe  circumflances,  that  the  nitrogene  is 
idiffipated,  while  the  hydrogene  unites  with  the  oxigene  of  the 
oxide,  and  forms  water. 

The  oxide  of  arfenick  haftens  the  vitrification  of  all  the  earths  ; 
but  the  glaffes  into  which  it  enters  as  a  component  part,  have 
the  property  of  cafily  becoming  tarniflied. 

Equal  parts  of  nitre  and  oxide  of  arfenick,  diftilled  in  a  retort, 
afford  a  very  red  and  almoil  incoercible  nitrick  acid.  Stahl  and 
Kunckel  obtained  it  by  a  procefs  nearly  fimiiar.  Macquer  hav- 
ing refumed  this  work,  carefully  examined  the  refidue  in  the  re- 
tort, and  found  that  it  was  a  lalt  foluble  in  water,  capable  of 
cryflallizing  in  tetrahedral  prifms  terminated  by  four-fided  pvra- 
2"nids,  unalterable  in  the  air,  fulible  by  a  moderate  heat,  but  with- 
out becoming  alkalized.  Mr.  Macquer  called  it  the  neutral  ar- 
fenical fait  :  he  fuppofcd  that  no  acid  could  deccmpofe  it.  But 
Mr.  Pelletier  proved  that  the  fulphurick,  when  diftilled  with  it, 
difTengaged  its  acid. 

The  arfeniate  of  foda  differs  little  from  the  arfeniate  of  pot- 
afli.  Mr.  Pelletier  obtained  this  fait  cryftallized  in  hexahedral 
prifms,  terminated  by  planes  perpendicular  to  their  axes. 

By  thefe  feveral  experiments,  Mr.  Macquer  had  fhewn  that 
arfenick  anfwered  the  purpofe  of  an  acid  in  thefe  combinations. 
There  remained  only  one  flep  therefore  to  be  made,  to  prove  that 
it  was  really  metamorphofed  into  an  acid  in  thefe  feveral  ope- 
rations ;  and  it  is  to  the  celebrated  Scheele  that  wc  are  indebt- 
ed for  this  difcovery.  His  capital  experiments  upon  inanganefe 
fiaturally  led  him  to  it. 


«^$  Acid  of  ArfenicL 

He  has  given  U3  two  procefies  to  obtain  this  arfenical  aciti,; 
:the  firft  by  mevnis  of  the  oxi^^enated  muriatick  acid,  and  the  oth- 
er by  the  nitiick  acid.  Thete  acids  are  diiHIled  from  the  oxide 
of  arfcnick  :  the  muriatick  acid  abandons  its  oxigene  to  the  osi^ 
ide  of  arfenick,  and  refuses  the  characters  of  the, ordinary  nnu- 
3:i?itick  acid.  The  nitrick  acid  is  itfelf  decorapofed  ;  and  one 
of  its  principles  is  diffipated,  while  the  other  is  fixed  and  com- 
.|)ines  with  the  arfenieal  oxide. 

This  acid  is  at  prefent  obtained  by  diftilliBg  ftx  parts  of  nitrick 
acid  from  one  of  oxide  gf  arfenick. 

Mr.  Pelletler  like  wife  propofes  to  decompofe  the  nitrate  of 
ammoniack  by  the  oxide  of  arfenick.  The  refidue  in  the  retort 
is  the  arfcniate  of  ammoniack,  from  which  the  alkali  may  bo 
driven  by  a  fire  long  kept  up.  The  refidue  is  a  vitreous  mafs, 
ilropgly  attrading  humidity,  and  falling  into  deliquium.  It  is 
the  pure  arfenieal  acid. 

Mr.  Pelletier  has  like  wife  decompofed  the  neutral  arfenieal 
fait,  by  mining  it  with  half  a  part  of  oil  of  vimol,  and  urging  ths 
tire  to  fuch  a  degree  as  to  ignite  the  veifels.  The  refidue  at  the 
bottom  of  the  retort  is  a  white  mafs,  which  attracts  humidity, 
and  is  the  arfenieal  acid.  A  white  powder  is  observable,  which 
is  found  to  be  the  fulphate  of  pot-afh  or  of  foda,  accordingly  as 
-th^  arfenieal  fait  has  foda  or  pot-alh  for  its  bafis. 

From  the  various  procefles  made  ufe  of  to -form  the  arfenieal 
acid,  it  is  evident  tliat  this  fubftance  is  nothing  but  the  arfenieal 
"QKide,  faturated  with  the  oxigene  which  it  takes  from  the  various 
bodies  digefted  upon  it.  The  nitrick  acid,  or  the  nitrates  ufed 
for  this  purpofe,  are  decompofed  ;  the  nitrous  gas  pafTes  over 
^ery  abundantly,  and  the  o^xgtn^  remains  mixed  and  united  wiih 
the  oxide  of  arfenick. 

This  acid  poiTeffes  the  concrete  form  »  but  it  attra£ls  the  hu* 
iTiidjiy  of  the  air,  and  becornes  refolved  into  a  fluid. 

It  h  fixed  in  the  fire  ;    but  if  it  be  heated  in  contact  with  a 
eoaly  fubft ance,  it  is  dcjcompofed,  and  the  oxide  exhnles  in  the 
•  -form  of  fumes.     It-is  reduced  into  arfenick,  according  to  M,r. 
Pellettier,  by  paffing  hydrogenous  gas  thr<)ugh  it. 

At  the  temperature  of  twelve  degrees  of  the  thermometer  of 
■Reaumur,  this  acid  requires  only  two  thirds  of  its  weight  of  w«- 
ifcer  to  diflblve  it  j  whereas  one  part  of  the  oxide  of  arfenick  re- 
quires twenty- four  of  water  tp  diflblve  it  at  the  fame  tempera- 
ture. 

This  acid,  when  difiblved  in  water  may  be  ag^in  concentraeeei^ 
.  afui  carried  to  the  ftate  of  a  tranfparent  glafs  without  any  alt^- 
ation  ;  for  it  is  not  by  this  treatment  deprived  of  its  power  of  at" 
trading  humidity  from  tiae  air. 


I 


Coanterpoifofi  agauijl  Arfen'ich,  ftg j^ 

When  k  is  id  this  ftate  of  concentration,  it  acls  ftrongly  on- 
^le  crucible,  and  dii?blves  the  alumine,  according  to  Mr.  JBcr* 
dioJlet's  experiments. 

Tfie  arfenical  acid,  faturated  with  ammoniack,  and  duly  evap^ 
orated,  forms  a  fait  cryftallized  in  rhomboids  which,  when  urg- 
ed by  heat,  lofes  its  water  of  cryftallization,  next  its  alkali,  and^ 
is  refolved  into  a  vitreous  mafs. 

Barytes  and  magnefia  appear  Ukewife  to  have  a  flronger  affini- 
ty with  this  acid  than  the  alkalis,  according  to  Bergmann.  Lime 
decompofes  the  neutral  falts  with  bafc  rif  alkali,  according  to  the 
experiments  of  the  fame  chcmift. 

Arfenick  is  ufed  by  the  dyers  *,  it  is  likewife  lifed  as  a  flux  in* 
glafs-houfes,  and  in  docimaftick  works  ;  it  alfo  enters  as  a  com- 
ponent part  into  fome  glazes.  Orpiment  and  realgar  are  very 
much  ufed  by  painters  ;  but  arfenick  i&  one  of  th^fe  produ<flion& 
whofc  advatitages  are  not  fufHcient  txD  compenfate  for  its  bad 
eiTecfls.  This  me^'ah  which  is  very  abundant,  and  very  fretquent- 
ly  met  with  in  mines,  caufes  the  dclirudtion  of  a  number  oP 
^'orfcmen  who  explore  them  :  being  very  volatile,  it  forms  a  dud 
■which  afi^e6i:s  and  deftroys  the  lungs  ;  and  the  unhappy  miners, 
after  a  langtiindng  lifie  of  a  few  years,  all  perifn,  fooner  or  later. 
The  property  which  itpoflelles  of  being  fbluble  in  water,  multiplies' 
and  facilitates  its  deftru£live  power ;  and  it  ought  to  be  profcrib- 
ed  in  commerce,  by  the  flritl  law  v.'hlch  prohibits  the  fale  of 
poifon  to  unkno\^^l  perfons*  Arfenick  is  everyday  the  inftrti- 
ment  by  which  vi<ftlms  are  facrificed,  either  by  the  h^nd  of 
wickednefs  or  imprudence.  It  is  oftcti  miftaken  for  fugar  ;  and 
rhefe  midakes  are  ?.ttended  with  the  moft  dreadful  confequenccs. 
Whenever  there  is  the  icafi:  reafoii  to  fufpe^l  its  preftncc,  the 
doubt  may  be  cleared  up  by  throwing  a  fniall  quantity  of  the 
powder  upon  heated' coals.  The  fmell  of  garlick,  and  the  white 
fumes,  arc  indications  of  the  pretence  of  arfenick.  The  fymp- 
toms  which  characterize  this  poifon  are,  a  great  conftriftion  of 
tlie  throat,  the  teeth  feton  edge,  and  the  mouth  Rrouj^ly  heated  y^ 
an  involuntary  fpitting,  with  extreitlc  pains  in  tlie  llomach  ; 
vomiting  of  glsirous  and  bloody  matter,  with  cold  fsveats  and- 
convulfions. 

Mucilaginous  drinks  have  been  long  ago  given  to  peffons 
poifoned  by  arfenick.  Milk,  fat  oiks,  butter,  &c.  have  been  fuc- 
ceirively  employed.  Mr.  Navier  has  projyofed  a  more  dirc£t 
«Jaunterpoifon.  He  prefcribes  one  dram  (gros)  of  falphure  of 
pot-afli,  or  liver  of  fulphur  to  be  diffolvcd  in  a  pint  of  water, 
which  the  patient  is  directed  to  drink  at  feveral  draughts  :  the 
fa-lphure  Urnites  to  the  arfenick,   and  deftroys  its  caullioiiy  and' 


i88  Cobalt. 

cfFeft.  When  thefe  firft  fymptoms  are  diffipated,  he  advifes  the 
ufe  or  mineral  falphureous  waters.  He  likewife  approves  of 
miik,  but  condemn;:,  the  ufe  of  oils.  Vinegar^  which  diflblves 
arfenick,  has  been  Hkcwife  recommended  by  Mr.  Sage. 


CHAPTER    11. 

Concerning   Cobalt. 

COBALT  was  employed  by  artiits  to  give  a  blue  col- 
our to  glafs,  long  before  it  was  fuppofed  to  contain  a  femi-metal. 
"We  are  indebted  to  Brandt,  a  celebrated  Swedifh  mineralogift, 
for  the  knowledge  of  its  properties,  and  metallick  chara£ler. 

The  fpecifick  gravity  of  fufed  cobalt  is  78 1 19.     See  Briflbn. 

Cobdt  is  combined  in  the  bowels  of  the  earth  with  fulphur, 
arfenick,  and  other  metallick  fubftances. 

1.  The  arfenical  cobalt  ore  is  of  a  grey  colour  more  orlefs 
deep,  dull  in  its  fracture,  and  becoming  black  on  expofure  to 
the  air,  in  confequence  of  an  alteration  in  its  arfenical  part. 

This  ore  of  cobalt  cryftallizes  in  fniooth  cubes,  and  aifecls 
feveral  varieties.  I  have  a  piece  which  has  the  form  of  tetrahe- 
dral  pyramids,  joined  bafe  to  bafe.  Thisfpecies  of  cobalt  fome- 
times  affects  a  confufed  crydaliization  in  dendrites,  and  is  then 
called  Knit-cobalt  ore.  Sometimes  it  is  found  in  protuberances, 
ftalaftites,  &c. 

2.  The  fulphureous  ore  of  cobalt  refembles  the  grey  filver  ore 
in  its  texture  :  it  contains  iron  and  filver  •,  and  efflorefces  of  a 
lllack  colour,  mixed  with  a  yellowilh  green. — Sage,  Annal. 
Chem.  t.  ii. 

Mr.  De  Lifle  pofTclTes  fpecimens  of  this  kind,  which  came 
from  the  mine  of  Batnaes  at  Riddarhyttan. 

3.  Cobalt  is  mineralized  by  fulphur  and  arfenick,  in  the  mine 
of  Tunaburg  in  Sundermania. 

The  crydaliization  of  this  fpecies  is  a  cube  ftriated  on  its  fix 
faces,  and  commonly  truncated  more  or  lefs  deeply  on  its  edges. 

This  ore  contains,  according  to  Mr.  Sage,  fifty- five  pounds  of 
arfenick,  eight  of  ful4)hur,  tvvo  of  iron,  and  tWrty-five  of  cobalt. 

4.  The  ores  of  cobalt  are  fomctimes  in  efflorefcence  ;  and 
the  fulphureous  ore  forms  by  its  decompofition  the  fulphate  of 
cobalt. 

The  fulphure  of  cobalt,  and  the  arfenical  cobalt  ore,  pafs  ta 
the  (late  of  oxide  in  their  decompofition  ;  and  the  furface  be- 
comes covered  with  a  colour  of  peach  flosvers,  rnore  pr  lefs  in- 


'  Afay  of  Cobalt  Ores,     Zaffer,  a  89 

tenfe.     It  is  fometlmes  coloured   with  an  elHorefcenCe  in  the 

I  figure  of  ftars  formed  by  radii  applied  to  each  other  collaterally, 
and  all  tending  to  a  common  centre.  This  is  an  indiftincSt  cryf- 
tallization,  in  which  Mr.  De  Lifle  thinks  he  obfer/ed  te^rahedral 
prifms  terminated  by  dihedral  fummits.  The  flowers  of  cobalt 
are  frequently  a  mere  pov/der,  more  or  lefs  coloured.  Thofe 
ores  which  are  in  a  ftate  of  complete  decompofition  are  called 
Soft  or  Earthy  cobalt  ores. 
i  To  aflay  an   ore  of  cobalt,   the  firft  procefs  is  torrefaftion. 

Two  hundred  grains  are  afterwards  fufed  with  an  ounce  and 
an  half  black  flux.  Mr.  Sage  is  confident  that  more  metal  is  ob- 
tained by  mixing  the  oxiJe  of  cobalt  with  two  parts  of  white 
glafs,  and  a  fmall  quantityef  coal. 

When  cobalt  is  mixed  with  biimuth  and  iron,  its  oxide  muft 
be  diftilled  with  equal  parts  of  the  mu'-iate  of  arnmoniack,  until 
the  fait  which  fublimes  in  the  neck  of  the  retort  has  acquired 
a  green  tinge.  Mr.  Sage,  who  gives  us  this  procefs,  obferves 
that  feven  or  eight  fublimations  are  fometimes  neceflary  to  de- 
prive the  cobalt  of  all  the  iron  andbifmuth  which  it  conraiir*. 

Cobalt  is  of  a  light  grey  colour,  compact  and  brittle.  It  is  not 
eafily  fufed,  is  not  volatile,  refills  cupellation,  and  refufes  to 
amalgamate  with  mercury. 

The  working  of  cobalt  ores  is  very  fimple.  It  confifts  in 
roafting  the  ore  in  a  revcrberatory  furnace  terminating  in  a  long 
chimney,  into  which  the  vapours  are  received.  Thefe  vapours> 
or  arfenical  fumes,  attach  themfelves  to  the  fides,  and  form  a 
crufl,  which  is  cleared  off  by  criminals,  who  are  condemned  to 
this  work  for  crimes  that  by  the  law  deferve  death.  The  cobalt 
ores  of  Saxony  afford  all  the  arfenick  of  commerce.  When  the 
oxide  of  cobalt  is  cleared  of  arfenick,  it  is  known  by  the  name 
of  ZafFer.  The  zafFer  of  commerce  is  mixed  with  three  fourths 
of  fand.  This  oxide,  fufed  with  three  parts  of  fand,  and  one  of 
pot-afh,  forms  a  blue  glafs,  which,  when  pounded,  fifted,  and 
afterwards  ground  in  mills,  included  in  large  caflcs,  forms  Smalt. 
In  order  to  obtain  the  blue  of  various  degrees  of  finenefs,  the 
fmalt  is  agitated  in  caflcs  filled  with  water,  and  pierced  with 
three  openings  at  difl^erent  heights.  The  water  of  the  upper 
cock  carries  out  ihe  lighteft  blue,  which  is  called  Azure  of  the 
Firft  Fire  :  the  heavier  particles  fall  more  fpeedily  •,  and  the 
azure  brought  out  by  the  water  of  the  three  cocks,  forms  the 
different  degrees  of  finenei's,  known  under  the  names  of  Azure 
of  the  Firft,  Second,  and  Third  Fire. 

Bohemia  and  Saxony  have  hitherto  poiTefl'ed  the  exclufive 
power  of  fupplying  us  with  thefe  products.      A  defcription  of 
thefe  capital  works  may  be  fecn  in  the  mincralogical  production* 
2...N 


ap^  '      Habitudes. of  Cobalt  nvith  Acids* 

of  Meflrs.  Jars.  The  works  of  Saxony  have  been  fupplied,  foir 
feveral  years,  by  the  cobalt  ore  difcovered  in  the  Pyrenean 
Mountains,  in  the  valley  of  Giften.  But  the  Comte  de  Beufi;  has 
formed  eftablifhmcnts  which  fecure  to  us  the  benefit  of  thi& 
commerce  y  and  he  has  even  been  fo  fortunate  as  to  find,  near 
the  village  of  Juget,  a  quartz  fufficicntly  charged  with  cobalt  to 
admit  of  being  fufed  without  any  addition  of  colouring  matter. 

The  eftablifhment  of  the  Comte  de  Beuft  is  capable  of  manu- 
fedluring  fix  thoufand  qAiimals  of  azure,  or  enamel  blue  j  and  is 
able  not  only  to  fupply  our  own  wants,  but  to  enter  into  compe- 
tition with  the  works  of  Saxony  for  thie  foreign  trade.* 

He  has  likewife,  in  concert  with  the  Baron  Dietrich,  difcov- 
ered the  procefs  of  making  powdeii  blue  ;  a  fecret  which  was 
cxclufively  in-  the  pofiefllon  of  the  Hollanders  till  the  prefent 
time. 

Smalts  are  ufed  iti'  the  prfeparadoiv  of  cloths,  laces,  linenSi? 
muilins,  thread,  &c. 

The  azures  are  mixed  with  ftarch,  and  form  the  bke  {\)  well 
known  and  univerfally  ufed  by  laundrefles. 

It  is  likewife  employed  in  forming  blue  paintings  on  fayence,' 
porcelain,  and  other  potteries  *,  cryftals  and  glaiTes  arc  coloured 
blue  by  this  fubftance  ;  and  it  is  alfo  ufed  in  painting  in  frefco* 

The  coarfeft  blues  are  ufed  by  the  confeclioners  and  others,, 
iai  the  way  of  ornament ;  and  in  Germany  they  are  ufed  as  fand 
for  writing-paper. 

The  confumption  of  fmalt,  azure,  blue  fands,  and  zafFers,  in 
^e  kingdom  of  France  only,  is  eftimated  at  four  thoufand  quin- 
tals, which  are  fold  from  feventy-two  to  fix  hundred  .Uvres  the 
quintal. 

Cobalt  is  foluble  in  the  acids.- 

Gne  part  of  this  metal,  diftilled  with  four  parts  of  fulphurick 
acid,  affords  the  fulphureous  acid  ;  and  the  refidue  in  the  retort 
li'S  the  fulphate  of  cobalt,  foluble  in  water,  and  capable  of  cryf- 
tallizing  in  tetrahedral  rhomboidal  cryftals,  terminating  in  a 
dihedral  fummit. 

Barytes,  magnefia,  lime,  atid  alkalis  de^cornpofe  this  &k,  and 
precipitate  the  cobalt  in  the  form  of  oxide. 

Gne  hundred  grains  of  cobalt  diflblved  in  the  fulphurick  acid, 
and  precipitated  by  foda,  afford  one  hundred  and  forty  grains  of 
precipitate,  and  one  hundred  2aid  fixty  when  precipitated  by 
chalk. 

*  A  defcfiptioa  of  the  works  of  the  Comte  de  Beufl:  rri^y  be  feen  i& 
the  Defcription  des  GlUs  des  Miner a'ny  dss  Forga,  st.  dif  &alinr  dc^s  Py- 
rsnsesjp  r  M*  h  Baron  da  J>ietrich* 


Nickel.  ap^t 

The  nltrick  acid  diflblves  cobalt  with  effervefcence.  The  fo- 
,;lution  affords  cryftals  in  needles,  which  have  not  been  ftriclly 
examined.  This  fah  is  deliquefcent,  boils, on  the  coals  without 
-detonating,  and  leaves  a  deep  red  calx.  I  have  feen  this  fait  in 
very  fliort  beautiful  hexahedral  pyramids.  It  decrepitates  and 
i'ufes  on  charcoal. 

The  muriatick  acid  does  not  diffolve  cobalt  in  the  cold,  but  by 
the  affiftance  of  heat  it  diffolves  a  portion  of  jit.  This  acidac^s 
more  effe6lually  upon  the  zaffer,  and  the  folution  is  of  a  very 
iine  green,  and  when  diluted  with  water  conftitutes  a  very  fin- 
.gular  fympathetick  ink  ;  for  it  pafles  from  a  lilack,  or  violet  col*» 
our,  to  purple,  green,  and  black. 

The  nitro-muriatick  acid  likewife  diffolves  cobalt,  and  rforms 
the  fympathetick  ink,  which  Hellot  has  called  the  Irik  of  Bifmuth, 

Ammoniack  likewife  diffolves  zaffer,  and  prqduces  a  liquor 
of  a  beautiful  red  colour. 


CHAPTER  ffL 

Concerning  Nickd, 

HYERNE  appears  to  have  been  the  firft  Who  treated  of  nick- 
el, under  the  name  of  Ivupfernickel,  in  1794,  in  a  work  on 
tiiinerals. 

Henckel  confidered  it  as  a  fpecies  of  cobalt,  qr  arfenick 
^ixed  with  copper. 

Cramer  has  likewife  placed  it  among  the  ores  of  copper  ;  and 
St  was  not  until  the  year  1751,  that  Cronlledt  obtained  a  new 
femi- metal  from  this  pretended  mixture. 

Kupfernickel  is  found  not  only  in  the  German  diftri6ts,  but 
likewife  in  Pauphlny  and  in  the  Pyrenean  Mountains.  In  dig- 
ging out  a  calcareous  ftone  for  building,  at  Bareges,  and  oppo- 
iite  St.  Sauveur,  fmall  veins  and  lumps  of  nickel  were  found  m 
the  calcareous  fpar,  fome  parts  of  which  were  reduced  to  tkc 
ilate  of  green  oxide.  Mr.  Sage,  v/ho  analyfed  that  of  Biber  ia 
Heffe,  and  that  of  Allemont,  found  it  to  contain  gold. 

In  order  to  obtain  nickel  from  its  ore,  it  muft  firlt  be  torrefied 
to  difengage  the  arfenick  ;  and  the  oxide  muft  then  be  fufed 
with  three  parts  of  black  flux,  and  a  fmall  quantity  of  coal. 
This  metal  is  of  a  reddifli  grey  colour. 

The  fpecifickgravity  of  fufed  nickel  is  7,8070.     Briffon. 

As  it  is  very  difficult  to  drive  off  all  the  arfenick  by  a  previ- 
ous torrefadion,  the  metal,  when  urged  by  a  violent  fire,  ftil! 
f-  ff:-rq  nrfenick  f^  efnne. 


2p  2  Prcperiies  of  Nickel  and  Bifmuth, 

The  methods  pointed  out  by  Bergmann  and  Arvidfon  to  pa* 
rify  nickel,  confill  in  repeated  calcinations  and  reductions  ;  but 
thefc  operations  feparate  the  arfenick  only  j  and  Bergmann  ad-* 
jnits  that  he  did  not  fucceed  in  completely  depriving  it  of  its  x-. 
ron,  though  he  treated  it  by  every  fuitable  method.  He  feems 
difpofed  to  confiderit  as  a  modification  of  iron. 

The  Diflertation  of  Bergmann  De  Nicolo,  Opufcula,  t.  ii. 
man  be  confulted  on  the  nature  of  this  metal ,  and  alfo  the  A« 
aalyfe  Chimique  of  Mr,  Sage,  &c. 

The  fulphurick  acid  diftilled  upon  nickel  affords  fulphureous 
acid,  and  leaves  a  greyifti  refidue,  which,  when  diffolved  in  wa- 
ter, communicates  to  it  a  green  colour. 

The  fulphate  of  nickel  efRorefces  in  the  air. 

Nickel  is  attacked  very  {Irongly   by  the  nitrick  acid. 

The  folution,  when  evaporated,  affords  cryftals  of  a  beautiful 
green,  in  rhomboidal  cubes. 

The  nitrick  acid  likewife  diflblves  the  oxide  of  nickel,  anxi 
forms  with  it  deliquefcent  cryftals  of  a  fine  emerald  green,  and 
of  a  rhomboidal  form,  according  to  Bergmann. 

The  muriatick  acid  diflblves  nickel  when  heated.  The  folu- 
tion produces  cryftals  of  the  mofl  beautiful  emerald  green,  and 
of  the  figure  of  long  rhomboidal  o6lahedrons. 

Cronftedt  has  taught  us  that  nickel  combines  with  fulphur 
by  fufion,  and  that  the  refult  is  a  hard  yellow  mineral,  with 
fmall  brilliant  facets.  The  fame  chemift  diflTolved  this  laft  met-, 
al  in  the  fulphure  of  pot-afh,  and  fprm^ed  a  compound  refem- 
t>Ung  the  yellow  copper  ores. 

Nickel  dqea  not;  arnalgamate  with  mercury. 


CHAPTER  IV. 

Concernl/tg  Btfrnuih* 

BISMUTH,  or  tin-glafs,  is  a  femi-metal  of  a  fliining  yellow-. 
i{h  white,  difpofed  in  plates  and  chatoyant.  It  has  fome  analo- 
gy  with,  lead  ;  and,  like  that  metal,  it  paflies  off  on  the  cupel, 
carrying  the  bafer  metals  along  with  it. 

The  fpecifick  gravity  of  fufed  bifmuth  is  9,^227. — See  Brif- 
fon. 

Bifmuth  is  the  rgoft  eafily  fufed  of  all  the  femi-metals,  afte:: 
till.     It  requires  only  the  ^ooth  degree  of  heat. 

It  is  found  in  various  ftates  in  the  bov/els  of  the  earth,  eithe;? 
native,  or  coja:;bined  with  fulphur,  arfenick,  or  pxigeae. 


Ores  of  B'lfmuth,  20 3 

1 .  Native  bifmutli  is  fometimes  cryftalHzed  in  cubes :  Walle- 
rius  and  Cronftedt  found  it  in  this  form  in  the  mines  of  Schnee- 
burg  in  Saxony.  Thefe  cryllals  often  re-unite  in  the  form  of 
dendrites,  in  the  fpathofe  or  quartzofe  gangues.  Native  bif- 
muth  is  found  in  mafl'es,  covered  with  protuberances  refemblin<j 
italadlites. 

Native  bifmuth  is  frequently  altered  by  a  flight  decompofi- 
tion  of  its  raetalick  furface. 

The  native  bifmuth  of  Saxony  is  fometimes  irifed,  and  mixed 
with  arfenick  :  it  has  a   reddifh   jafper  for  its  gangue. 

2.  Arfenical  bifmuth  is  of  a  whitifti  and  brilliant  grey  colour. 
This  ore  is  fometimes  covered  with  an  ochre  of  bifmuth,  and 
often  contains  cobalt.  I  have  feen  pieces  of  arfenical  bifmuth, 
/rom  Schneeburg,  in  the  form  of  dendrites  on  a  gangue  of 
jafper. 

3.  We  are  indebted  to  Mr.  Cronftedt  for  the  knowledge 
of  a  fulphureous  ore  of  bifmuth.  That  which  he  has  defcribed 
is  of  a  bluifh  brilliant  grey  colour. 

This  fpecies  frequently  pofTefTes  the  lamellated  texture  of  the 
large  plated  galena,  which  has  caufed  Linnaeus,  Wallerius,  and 
and  others,  to  give  it  the  name  of  Galena  of  Bifmuth.  It  i$ 
found  at  Batneas,  at  Riddarrhitan  in  Weflmanland.  It  decrep- 
itates on  heated  coals,  and  reijuires  to  be  pulverized,  in  order 
%Q  torrefy  it  without  lofs. 

The  galena  of  Bifmuth  is    fometimes  flriated. 

The  fulphureous  ore  of  Bifmuth  is  fometimes  compadf,  of 
an  obfcure  colour,  fprinkled  with  fmall  brilliant  points.  That 
of  Schneeburg,  in  Saxony  is  of  this  kind. 

Mr.  De  la  Peroufe  difcovered,  in  I773>  ^^  ^^^^  mountains  of 
Melles  in  Cominges,  in  the  quarter  called  Les  Raitz,  an  ore  of 
bifmuth,  which  refembles  this  fmall  plated  galena,  and  has  no 
external  difference,  excepting  that  it  is  lefs  heavy.  This  ore  is 
mineralized  by  fulphur,  in  the  proportion  of  thirty-five  livers 
per  quintal. 

4.  Cronftedt,  Linnaeus,  Jufti,  and  De  Born,  have  fpoken  of  a 
l^ifmuth  ore  of  a  greenifti  yellow,  found  in  Saxony,  and  in  Swc- 
<}en.  Mr.  Sage  communicated  to  the  Academy,  on  the  17th  of 
Auguft,  1780,  the  analyfis  of  an  earthy  folid,  yellowifh  green 
ore  of  bifmuth.  He  obtained  quartz  in  the  proportion  of  one 
third,  feme  carbonick  acid,  thirty-fix  pounds  of  bifmuth  per 
quintal,  and  twenty-four  grains  of  filver:  he  found  neither  cop- 
per nor  iron.  Befides  this  green  ore,  he  analyfed  a  yellow  acid 
(lightly  brilliant,  and  fometimes  femi-tranfparent  ore,  which  af- 
forded him  nearly  the  fame  refults,  but  nine  pounds  more  of 
^ifmi^th. 


2^4  Habltuifes  avd  Magtftery  of  Bifmuih, 

This  oxide  niufl:  be  fufed  in  the  blaft  furnace. 

The  fufibility  of  bifmuth  renders  the  working  of  this  ere  ve- 
ry hnipie,  and  the  apparatus  may  be  varied  in  feyeral  ways. 
Nothing  more  is  neceifary  than  to  throw  the  ore  into  the  fire, 
and  to  make  a  cavity  underneath  to  receive  the  femi-metal. 

Bifmuth,  when  heated  to  rednefs,  burns  with  a  blue  flame, 
fcarcely  perceptible.  Its  oxidp  rifes  in  the  form  tjf  a  yellowiil) 
fume,  which,  when  condenfed,  forms  the  flowers  of  bifmuth- 
Its  weight  is  increafed,  twelve  per  cent,  in  pafiing  to  the  ftate  of 
oxide. 

Mr.  Darcet  has  converted  Bifmuth  into  a  gl^ft  of  a  dull  vio, 
let  colour. 

Bifmuth  may  be  fubftituted  inftead  of  lead,  in  the  procefs  of 
cupellation.     Its  vitrification  is  even  more  fpeedy. 

The  fulphurick  acid,  boiled  on  bifmuth,  fufl^ers  fulphureou^ 
acid  to  cfcape,  and  partly  difTolves  the  forji-metal.  The  ful- 
phate  of  bifmuth  does  not  cryftallize,  but  is  very  deliquefcent. 

The  nitrick  acid  attacks  bifmuth,  and  is  very  fpeediiy  decom- 
pofed.  Nitrous  gas  is  difengaged,  while  the  oxigene  is  fixed  in^ 
combination  with  the  metal.  There  is  nevcrthelefs  a  pqrtioi^ 
diflblved  which  is  capable  of  forming  a  fait  in  rhomboidal,  tetra- 
hedral  prifms,  terminating  in  a  tetrahedral  pyramid  with  unequal 
faces.  This  nitre  detonates  weakly  with  reddifi>  fcintiilations  ; 
and  melts,  fwelis  up,  anfi  leaves  an  oxide  of  a  greenifli  yellow? 
colour. 

This  fait  lofes  its  tranfparency  in  the  air*  at  the  fame  time 
that  its  water  of  cryftallization  flies  off. 

The  muriatick  acid  does  not  2i€t  on  bifmuth  but  in  the  courfe 
of  a  confiderable  time  ;  and  for  this  purpofe  it  muft  be  highly 
concentrated.  The  muriate  of  bifnmth  is  of  difficult  cryflalli- 
zatlon,  and  ftrongly  attracts  the  humidity  of  the  air. 

Water  precipitates  this  femi-metal  from  all  its  folutions; 
and  the  precipitate,  when  well  wafhed,  is  known  by  the  name  of 
Magiftery  of  Bifmuth,  or  white  paiiit  for  the  complexion.  This 
"white  is  ufed  as  a  pigment  for  the  Ikin  ;  but  itrong  or  fulphu- 
-reous  vapours,  and  even  the  animal  tranfpiration,  convert  it  into 
rnetal,  and  alter  its  colours.  The  hair-dreflers,  when  they  are 
^efirous  of  converting  hair  to  a  black  colour,  fmear  it  with  po- 
matum prepared  with  the  magiftery  of  bifmuth. 

Bifmuth  is  ufed  by  the  pewterers  to  give  hardnefs  to  the  mCr 
tallick  compofition  of  pewter. 

Mr.  Pott  has  publiflied  a  differtation,  in  which  he  affirms  that  ; 
phyficians  have  made  ufe   of  fome  preparations  of  this  femi- 
metal  :    but  it  is  proper  that  it  fhould  be  prohibited,  becaufe  it 
almoft  always  retains  a  portion  of  arfeiii^k,  aad  itfelf  partakes  of 
the  noxious  prppcrties  of  le^d, 


jllloy  of  Bifmuth,     Anthmny,  2p^ 

The  white  of  bifmuth  is  very  much  ufed  as  a  paint  for  the 
complexion.  Its  various  folutions  form  fympathetick  inks, 
which  are  more  or  lefs  curious,  on  account  of  the  facility  with 
which  this  oxide  is  altered,  and  becomes  black. 

Schluter,  in  hisTreatife  of  the  Fufion  of  Ores,  pretends  tliat 
it  mav  be  ufed  in  making  the  azure  blue  glafs.  But  it  appears, 
from  his  own  account,  that  he  made  ufe  of  a  bifmuth  ore  very 
rich  in  cobalt.  For  he  fays,  that  a  moderate  fire  caufes  this  ore 
to  fvfFer  its  bifmuth  to  flow  out,  and  that  refidue  is  a  grey  and 
fixed  earth,  which  may  be  employed  to  advantage  in  making  the 
blue. 

This  femi-metal  unites  with  all  the  metals  ♦,  but  very  difficult 
ly,  in  the  way  of  fufion,  with  the  other  femi-metals,  or  the  me.- 
tallick  oxides.  Antimony,  zijic,  cobalt,  and  arfenick  refufe 
this  union. 

Bifmuth,  fiifed  with  gold,  renders  it  eager,  and  communi- 
cates to  it  its  own  colour.  It  does  not  render  (ilver  fo  brittle  as 
gold  :  it  diminifhes  the  fed  colour  of  copper,  but  is  deprived  of 
its  own  colour  by  uniting  with  lead  5  the  two  metals  in  this  cafe 
forming  an  alloy  of  a  grey  colour.  When  bifmuth  is  mixed  ia 
a  fmall  proportion  with  tin,  it  gives  it  a  greater  degree  of  bril- 
liancy and  hardnefs.  It  may  be  united  with  iron  by  a  violent 
heat. 

Bifmuth  amalgamates  with  mercury,  and  forms  a  fluid  alloy  ; 
d  circumftauce  which  has  induced  certain  unprincipled  drug- 
gifts  to  mix  it  with  that  metal.  The  fraud  may  be  known 
from  the  mercury  being  lefs  fluid  than  before,  and  no  other  teft: 
is  neceflary  than  to  diflbflve  the  mixture  in  fpirit  of  nitre  ;  for  the 
bifmuth  will  be  precipitated  by  the  addition  of  water. 

This  property,  however,  of  amalgamating  completely  with 
mercury,  may  caufe  it  to  be  applied  with  advantage  in  the  fil- 
vering  of  glafies,  by  an  amalgam  of  tin,  bifmuth,  and  mercury. 
This  is,  perhaps,  the  circumftance  which  has  obtained  it  the 
name  of  tin-glafs. 

The  fufible  alloy  of  Mr.  Darcet  is  a  mixture  of  eight  parts  of 
bifmuth,  five  of  lead,  and  three  of  tin.  It  melts  in  water  at  the 
feventy-third  degree  of  Reaumur,  and  Hows  like  mercury. 


CHAPTER    Y. 

Concerning  Antltnony, 

ANTIMONY  is  a  femi-metAl  which  has  fingularly  engfagcd 
the  attcntioi)  of  alchemilU.     They  confidercd  it  as  the  bafis  of 


±C}6  Ayfemdal  Ore  of  Antimony. 

their  great  work  ;  and  it  is  defcribed  in  their  writings  under 
the  names  of  the  Radical  Principle  of  Metals,  Sacred  Lead,  &c. 

This  femi-metal  is  famous  for  the  difputes  which  were  maiii- 
tained  concerning  it,  at  the  beginning  of  the  fixteenth  centur)\ 
It  was  prohibited  by  a  decree  of  parliament,  at  the  folicitaticn 
of  the  faculty  of  Paris.  Poumier  of  Caen,  a  fkilful  phyficiaa 
and  chemift,  was  degraded  by  the  Faculty  of  Medicine,  for  hav- 
ing employed  it  in  1609. 

This  fame  proscribed  metal  was  re-eftablifhed  in  1624;  and 
at  prefent  affords  the  moll  powerful  remedies  poflefled  by  the 
medical  art. 

Bazilius  VaJentinus,  a  zealous  partizan  of  antimony,  pleaded 
its  caufe  with  much  warmth  and  enthufiafm,  in  a  work  entitled 
Currus  Triumphalis  Antimonii  :  and  Lemery  has  written  a  large 
volume  to  decry  the  preparations  of  this  femi-metah 

As  this  fubftance  afforded  employment  for  a  long  time  to  the 
alchemifts,  its  fludy  is  rendered  particularly  difficult  by  the  mul- 
tiplicity of  preparations,  and  the  barbarous  names  which  have 
been  given  to  them,  and  to  the  variety  of  proceires.  But  by  con- 
founding preparations  of  the  fame  nature  *,  by  bringing  the  anal- 
ogous produOs  together,  rejecting  at  the  fame  time  the  numer- 
ous lift  of  barbarous  names  which  have  been  beftowed  on  one 
and  the  fame  thing  ;  and  by  reducing  the  procelTes  to  that  fim- 
plicity  of  which  the  well  known  preparations  are  fufceptible  ; 
we  mav  fucceed  in  forming  an  accurate  and  precife  idea  of  the 
nature  and  properties  of  this  metal. 

Antimony  is  found  in  the  bowels  of  the  earth,  in  four  differ- 
ent Hates. 

1.  In  the  metallick  form. 

2.  Combined  with  arfenick. 

3.  Mineralized  with  fulphur. 

4.  In  the  ftate  of  oxide. 

I.  Some  authors  pretend  that  antimony  in  the  metallick  llatj^ 
was  difcovered  in  the  year  1748,  by  Ant.  Swab,  in  the  mine  of 
Sahlburg,  in  Sweden.  Swab  affirms  that  it  has  the  colour  of 
filver,  that  its  texture  is  formed  of  large  brilliant  plates,  and  that 
it  eafily  amalgamates  with  mercury.  Cronltedt,  Wallerius, 
Linnseus,  and  Cartheufer,  do  not  hefitate  to  admit  of  native  an- 
timony ;  but  Lehman,  Jufti,  and  Vogcl  deny  its  exiftence  :  and 
Mr.  De  luiile  thinks  that  this  pretended  regulus  is  nothing  but 
the  white  arfenical  ore  of  antimony.  The  abbe'jMongez  affirms 
ihat  he  has  difcovered  native  antimony  at  Allemont  in  Dau- 
phiny.  It  is  the  fame  ore  which  Mr.  Sage  has  djfcribed  under 
the  name  of  the  Arfenical  Ore  of  Antimony. 


'Sulphureous    Ore   of  Antimony,  2py 

If  this  native  Antimony  really  exifts,  it  is  probably  cryflalliz- 
^^d  like  the  metal  itfelf,  which  is  known  to  us,  and  whofe  cryf- 
^Bals  are  either  o6lahedrons  inferted  one  in  the  other,  or  cubei 
^^Blaced  one  upon  each  other  flantwife. 

^H  2.  The  arfenical  ore  of  antimony  may  be  confidered  as  a  true 
^^Kegulus  by  thofe  who,  after  Bergmann,  do  not  admit  of  arfenick 
^HL  a  mineralizer :  for  the  ore  is  then  confidered  as  an  alloy  of 
^^Bie  two  reguli. 

^^F  This  ore  is  as  white  as  filver,  and  exhibits  large  facets  like  an- 
^^pmony.     The  fpecimcn  was  fent  from  Allemont  in  Dauphiny, 
^^o  Mr.  Sage.     Its  gangue  is  quartz.     Small  fafces  of  the  grey- 
and  red  ores  of  antimony  firiated  and  radiated,  and  rtot  contain- 
ing arfenick,  are  fometimes  found  in  the  cavities  of  this  ftone. 
The  antimony  and  the  arfenick  exift  in  the  metallick  ftate  irt 
this  ore.     The  arfenick  adheres  fo  (trongly  to  the  antimony  that 
It  cannot  be  difengaged  by  torrefa6lion.      Mr.  Sage  combined 
the  ore  with  fulphur,  and  obtained  orpiment  and  realgar.     This 
mineralogid  has  concluded,  from  his  analyfes,  that  the  arfenick 
exifted  in  the  proportion  of  fixteen  pounds  in  the  hundred. 

3.  Antimony  is  ufually  minerali:ied  by  fulphur,  in  which 
combination  it  exhibits  three  or  foiir  very  diftinO  varieties.  It 
is  fometimes  cryflallized  of  a  grey  colour  inclining  to  blue. 
The  cryftals  are  vety  frequently  flender,  oblong,  hexahedral 
prifms,  terminated  by  tetrahedral  pyramids.  The  mines  which 
are  wrought  in  Auvergne  afford  us  beautiful  prifms,  of  the 
fame  geometrical  form,  but  thicker  than  thofe  of  the  antimony 
of  Hungary.  Thefe  lad  cryftals  foon  become  of  an  irifed  coK 
our;  but  thofe  of  the  mines  of  Auvergne  are  not  fo  fpeediljr 
changed.  I  poflefs  a  large  fpecimen  of  antimony  from  the 
neighbourhood  of  Alais,  which  is  entirely  covered  with  cryftals 
perfe6lly  fimilar  to  thofe  of  Hungary.  It  frequently  happens 
that  thefe  cryftals  are  confufed  and  indiftin£l:,  in  which  cafe  the 
ore  appears  to  be  formed  of  very  llender  prifms  applied  fidewife 
to  each  other.  That  which  is  called  plumofe  antimony  does 
not  differ  from  thefe  varieties,  excepting  that  its  cryftals  are  very 
flender  and  detached.  They  are  ufually  of  a  blackifh  grey. 
This  variety  has  been  arranged  among  the  ores  of  fdver,  becaufe 
for  the  moft  part  it  contains  that  metal. 

Ores  of  antimony  have  been  found  in  feveral  parts  of  France; 
but  our  province  of  Languedoc  exhibits  very  curious  fpeci- 
mens.  We  have  them  at  Malbos  in  the  county  of  Alais.  This 
mineral  has  been  wrought  in  the  diocefe  of  Uzes;  but  the 
want  of  confumption  has  prevented  the  works  from  going  on 
with  fpirlt.  Mr.  De  Genfanne  hasobferved  in  Vivarais  a  large 
vein  of  ore  of  antimony  in  a  ftratum  of  pit-  coal. 
2..0 


apS  Procejfesy  isfc,  wiib  Antmo7ty. 

The  decompofition  of  the  fulphureous  ore  of  atitimony  pro* 
duces  the  red  antimonial  ore.  The  red  ore  more  efpecialljr  ac- 
companies the  fpecular  antimony  of  Tufcany.  Its  furfaces  ap- 
pear to  be  corroded  or  rendered  curious  by  decompofition  5  and' 
when  a  piece  is  broken,  it  emits  a  powder  which  has  the  proper- 
tics  of  kermes. 

The  decompofition  of  fulphureous  antimony  like  wife  produ-- 
ces  the  fulphate  of  antimony.  Some  varieties  of  thefe  antimo- 
nial decompofitions  may  likewife  be  fceii  in  the  Analyfe  Chim- 
jque  of  Mr.  Sage. 

Antimony  is  found  in  two  ftates  in  the  courfe  of  trade  ;> 
namely,  in  the  form  of  crude  antimony,  and  in  the  m'etallick 
form. 

Crude  antimony  is  nothing  c\(q  but  the  fulphureous  ore  of  an- 
timony cleared  of  its  gangue.  For  this  purpofe  the  ore  is  put 
into  pots  pierced  at  the  bottom,  and  difpofed  upon  other  pots> 
buried  in  the  earth.  The  uppermofl  pots  which  contain  the  min- 
eral are  then  heated  ;  the  antimony  becomes  fufed,  and  flows, 
together  with  its  fulphur,  into  the  lower  veflels,  while  the  gan- 
gue remains  in  the  upper  pots. 

i^s  the  mixture  of  antimony  and  fulphur  is  very  fufrble,  this 
procefs  may  be  varied  in  a  thoufand  ways.  I  have  myfelf  wrought 
-an  antimonial  ore  with  the  greateft  economy,  by  fufing  it  in  a 
furnace,  over  the  arch  of  which  I  had  difpofed  the  ore  broken 
into  pieces  of  five  or  fix  pounds  weight  each.  The  heat  was 
communicated  to  the  whole  mafs  by  five  openings  in  the  arch  or 
roof  J  and  the  antimony,  as  it  melted,  ran  down  on  the  outfide 
of  the  furnace  by  means  of  channels  cut  in-  the  convex  part  of 
the  dome.  This  method  afforded  forty  quintals  of  antimony  in 
twenty-feven  hours,  by  the  confumption  of  between  twenty  and 
thirty  quintals  of  combuflible  matter. 

We  are  acquainted  with  two  methods  of  depriving  crude  an- 
timony of  its  fulphur.  i.  The  flow  and  gradual  calcination  of 
the  ore,  which  affords  a'  grey  oxide,  and  this  urged  by  a  violent 
Keat  is  converted  into  a  reddilh  and  partly  tranfparent  glafs  of 
antimony.  It  does  not  affume  this  tranfparence  unlefs  it  has 
been  perfectly  fufedi  The  glafs  of  antimony  is  a  violent  corro- 
five,  but  is  capable  of  being  corrected  by  mixing  or  kneading  it 
with  yellow  wax,  and  afterwards  burning  off' the  wax  ;  or  other- 
wife  by  triturating  it  with  a  volatile  oil.  This  is  the  cerated 
antimony  of  Pringle,  fd  much  extolled  in  dyfenteries.  2.  Gr 
other  wife,  the  antimony  may  be  deprived  of  its  fulphur  by  pro- 
jelling  into  an  ignited  crucible  a  mixture  of  eight  parts  of  crude 
antimony,  fix  of  tartar,  and  three  of  nitre.  By  keeping  this 
mixture  for  a  certain  time  in  fufion,  the  antimony  is  obtained^ 
in  the  metalligk  ftate. 


'  Habitudes  of  Antimony,,  ,299 

In  the  large  works  antimony  is  torrefied  in  an  oven  refembling 

i^^at  of  the  bakers.     Fifty  pounds  of   dried  wine  lees  or  tartar 

H||re  mixed  with  a  hundred  pounds,  of  the  oxide  of  antimony,  and 

^^lie  mixture  is  then  fufed  in  proper  crucibles.      The    metallick 

button  contains  the  form. of  the  crucible  ;    and  thefe  loaves  of 

antimony  exhibit  a  ftar  on  their  upper  furface,    which  has  been 

confidered  as  peculiarly  chara(fteriftick  ;    but  is  in  facl  nothing 

.more  than  a  confufed  cryftallization  formed  by  odahedrpns  in- 

fcrted  one  in  the  other. 

Copper,  filver,  and  iron,  when  fufed  wifh  the  fulphure  of  an- 
timony, feize  its  fulphur,  and  reduce  it  to  the  ftate  of  regulus. 
This  has  been  diftinguifhed  by  the  name  of  the  metal  employ- 
,ed.     Thus  we  hear  of  the  regulus  of  Mars,  of  Venus,  &c. 

Antimony  is  difficult  of  fufion  *,  but  when  once  melted  it 
emits  a  white  fume  known  by  the  name  of  Argentine  Snow,  or 
FJowers  of  antimony.  Thefe  fumes,  when  coiledted,  form  very- 
brilliant  prifmatick  tetrahedral  cryftals :  Mr.  Pelletier  has  obtain- 
ed them  in  tranfparent  o£lahedrons.  The  argentine  flowers  of 
antimony  are  foluble  in  water,  which  they  render  emetick.  The 
volatility  and  folubility  of  this  fublimed  oxide  exhibit  a  refem- 
blance  with  the  oxide  of  arfenick  before  treated  of.  We  are  in- 
debted to  Rouelle  for  thefe  obfervations  on, the  properties  of  this 
antimonial  oxide. 

Antimony  is  very  flightly  changed  by  expofure  to  air,  in  which 
;it  long  preferves  its  brilliancy. 

The  fpecifick  gravity  of  fufed  antimony  is  6,7021. — See 
BriiTon. 

The  fulphurick  acid,  by  flow  ebullition  upon  this  metal,  is 
.partly  decompofed.  Sulphureous  gas  firft  efcapes,  and  fulphur 
itfelf  is  fublimed  towards  the  end.  When  four  parts  of  the  acid 
are  ufed  with  one  of  the  antimony,  therefidue,  after  the  action 
of  the  acid,  confifts  of  the  metallick  oxide,  with  a  fmall  quantity 
of  the  fulphate  of  antimony,  which  may  be  feparated  by  means 
-of  diftilled  water.  This  fulphate  is  very  deliquefcenr,  and  is 
eafily  decompofed  in  the  fire. 

The  nitrick  acid  is  decompofed  upon  this  femi-metal  with 
great  facility.  It  oxides  a  confiderable  part,  and  diflblves  a  por- 
tion, which  may  be  fufpended  in  water,  and  forms  a  very  deli- 
.quefcent  fait,  decompofable  by  heat.  The  oxide  prepared  by 
this  means  is  very  white,  and  very  difficult  of  reduction.  It  is 
a  true  bezoar  mineral. 

The  muriatick  acid  a6ls  upon  antimony  only  by  a  long  digef- 
,tion.  Mr.  Fourcroy  has  obferved  that  this  acid,  long  digefted 
upon  the  metal,  diflblves  it ;  and  that  the  muriate  of  antimony 
c/otained  by  a  (Irong  evaporation  in  the  form  of  fmall  needles, 


30O  Aniitnontal  Preparations, 

is  very  dellquefcent.  It  is  fufible  in  the  fire,  and  likewife  vol- 
atile. Mr.  Monnet  has  proved  that  twelve  grains  of  the  oxide 
of  antimony  are  fufficient  to  faturate  half  an  ounce  of  the  ordi- 
nary muriatick  acid.  Meflrs.  Monnet  and  De  Fourcroy  have  al- 
ways found  that  there  is  a  portion  of  the  muriate  of  antimony 
which  is  not  volatilized  by  the  fire  :  this  depends  upon  its  be- 
ing flrongly  oxided  or  calcined. 

If  two  parts  of  the  corrofive  muriate  of  mercury,  and  one  of 
antimony,  be  diftilled  together,  a  very  flight  degree  of  heat 
drives  over  a  butyraceous  matter,  which  is  called  butter  of  an- 
tirnony,  or  the  fublimed  muriate  of  antimony.  It  may  be  pre- 
fumed  that  the  acid  in  this  compofition  is  in  the  ftate  of  pxige- 
iiate4  muriated  acid,  as  it  is  in  the  corrofive  fublimate. 

The  fubhmed  muriate  of  antimony  becomes  fluid  by  a  very 
gentle  heat  ;  and  by  virtue  of  this  prpperty  it  may  conveniently 
be  poured  from  one  vefTel  to  another  :  for  nothing  more  is  nec- 
eflary  than  to  plunge  the  bottle  which  contains  it  into  hot  wa- 
ter, and  the  muriate  may  then  be  poured  put  in  its  hquid  ftate. 

I  have  feveral  times  obferved  this  muriate  of  antimony  cryf- 
tallized  in  hexahedral  prifms  with  dihedral  fummits  :  two  fide? 
of  the  prifm  are  inclined,  and  form  that  which  the  ancient 
chemifts  diftinguifhed  by  the  name  of  cryftals  in  the  form  of  a 
tomb.  This  muriate  is  ufed  as  an  efcharotick.  When  the  fait 
is  diluted  with  water,  a  white  powder  falls  down,  called  pow- 
der of  algarpth,  or  niercurius  vitie.  This  powder  does  not 
contain  an  atom  of  the  muriatick  acid,  and  is  merely  an  oxide 
of  antimony  produced  by  that  acid. 

Simple  water  has  fome  adion  upon  this  femi-metal ;  for  we 
find  that  it  becomes  purgative  by  remaining  in  contacTt  with  it. 
Wine,  and  the  acetous  acid,  completely  diflblve  it  :  but  the  e- 
nietick  wine  is  an  uncertain  remedy  ;  bccaufe  it  is  impoflTible 
to  determine  with  abfolute  certainty  the  degree  of  its  energy, 
which  depends  upon  the  very  variable  degree  of  acidity  of  the 
wine  made  ufe  of.  The  emetick  wine  ought  not  therefore  to 
be  ufed  but  in  external  applications. 

The  gaftrick  fluids  likewife  diflblvethis  femi-metal,  as  is  pro- 
ved by  the  famous  perpetual  pills.  This  purgative  has  been 
diftinguiflied  by  the  name  of  Perpetual  Pills ;  becaufe,  being 
very  little  alterable,  the  pill  may  be  tranfmitted  from  generation 
to  generation. 

The  acid  of  tartar  forms  a  very  well  known  fait  with  antimo- 
ny, which  is  much  employed  in  medicine  under  the  name  of  E^ 
metick  Tartar,  Stiblated  Tartar,  or  fimply  Emetick.  It  is  this 
fait  which,  in  the  New  Nomenclature,  is  diftinguifhed  by  the 
name  of  antimoniated  Tartrite  of  Pot- ufli.  ■•     ^ 


jintimonial  Preparations,  301 

In  the  examination  of  the  various  authors  who  have  treatd 
of  the  preparations  of  this  remedy,  as  well  as  by  comparing  the 
inoft  celebrated  difpenfatories,  we  do  not  find  two  which  pro- 
pofe  an  uniform  procefs  which  is  conftant  and  invariable  in  its 
efFeds. 

Some  prefcribe  the  crocus  m^tallorum,  or  femi-vitreous  ox- 
ide of  fulphurated  antimony  j  others  the  giafs  of  antimony ; 
others  the  liver  of  antimony,  or  fulphurated  oxide  of  antimony  : 
and  others  the  fublilned  oxide  :  fome  combine  feveial  of  thefe 
fiibflances.  But  all  in  general  adopt  cream  of  tartar,  or  the  acid- 
ulous tartrite  of  pot-a(h,  as  a  folvent. 

The  procefles  vary  not  only  in  the  choice  of  the  fubftances  to 
be  made  ufe  of,  but  even  in  the  proportions  in  which  they  are 
Xo  be  employed.  We  likewife  find  varieties  in  the  quantity  of 
"water  ufed  as  a  vehicle,  which  is  not  an  indifferent  circumftance  j 
in  the  time  prefcribed  to  digefl-  the  fubftances  together,  a  cir- 
cumftance of  the  greateft  conlequence  to  be  afcertained,  becaufc 
the  faturation  of  the  acid  depends  abfolutely  and  eilentially  upori 
it.  The  choice  of  vefTels  muft  likewife  influence  the  efFe(^  of 
this  remedy.  Hoffmann  has  affirmed  that  the  emetick  lolt  its 
cffedl  by  a  long  ebullition  5  and  Mr.  Baume  has  proved  that 
iron  precipitates  the  antimony  after  a  time,  and  confequently 
that  the  iron  veflels  prefcribed  in  certain  difpenfatories  ought  to 
be  rejeOed. 

This  variety  in  the  procefTes  muft  neceffarily  influence  the  re- 
fult  •,  and  we  cannot  be  much  furprifed  that  Geoffroy,  who  an- 
alyfed  feveral  antimoniated  tartritesof  pot-afli,  fhould  have  found 
from  thirty  grains  to  two  gros  and  ten  grains  of  metal  in  the 
ounce  of  this  fait. 

Is  it  not  therefore  of  great  confequence  to  prefcribe  a  uniform 
procefs,  whofe  product  fhould  be  invariable  ?  Thefe  heroick 
iremedies,  which  operate  in  fmall  dofes,  ought  to  produce  con- 
ftant and  invariable  efl^ec^s  through  all  Europe.  It  M'ould  be 
much  more  advantageous  that  folcmn  proceedings  fliould  be 
made  for  the  preparations  of  thefe  adiive  remedies,  than  for  the 
compofition  of  the  theriaca,  a  true  pharmaceutick  monfter,  the 
dofe  of  which  may  with  impunity  be  varied  from  a  few  grains 
up  to  three  hundred.  It  follows,  from  the  variety  of  the  effe^s 
of  thefe  fovereign  remedies,  that  confultations  become  almoft 
inefledlual ;  becaufe  the  phyfician  prefcribes  according  to  the 
cffefts  of  the  remedies  he  is  in  the  habit  of  ufing  ;  and  the  arc 
of  medicine  becomes  no  better  than  a  difcouraging  alternative 
^f  fuccefs  and  difappointment. 

At  MontpeUier>  the  emetick   a£ls  in  a  dofe  of  one   or   two 
grains  \    but  in  other  places   it  does  not  operate    in  a  lefs  dofe 


3C2  ji7itimomal  Preparations. 

than  ten  or  twelve  :  and  the  ftibiated  tartar  fold  by  thofe  wholcr 
iale  dealers  in  medicine,  who  fupply  the  country  apothecaries^ 
is  uliially  nothing  but  the  fulphate  of  pot-afh,  or  vitriolated  tar- 
tar moiftened  with  a  folution  of  emetick.  It  is  a  thing  greatly 
to  be  defired,  that  government,  which  does  not  apply  its  itamp  of 
approbation  to  objects  of  luxury  until  they  have  pafled  a  rigid 
infpe£tion,  fliould  prohibit  traders,  from  circulating  with  impu- 
nity, products  upon  which  the  health  of  the  citizen  ,fo  eiTentiai- 
ly  depends.  Thefe  are  the  frauds  and  deceptions  which  have 
engaged  me  to  form  an  eftabiiOiment  of  chemical  produi^s,  in 
-which  intelligence  and  probity  prefide  over  all  its  operations  5 
and  I  have  fucceeded  in  my  laboratories  fo  f in-  as  to  condudl  the 
proceiTes  with  fufficient  economy  to  afford  produds  faithfully 
made  up,  and  invariable  in  their  effects,  at  the  fame  price  as 
thofe  fophifticated  drugs  with  which  the  publick  has  hitherto 
-been  poifoned. 

The  mod  accurate  procefs  for  raakin^j  an  excellent  emetick 
confills  in  taking  very  tranfparent  glafs  of  antimony,  grinding 
it  fine,  and  boiling  it  in  water,  with  an  equal  weight  of  cream 
of  tartar,  until  this  fait  is  faturated.  By  filtration,  and  evapora- 
tion with  a  gentle  heat,  and  fubfequent  repofe,  cryffals  of  the 
antimoniated  tartritc  of  pot-afh  are  obtained,  whofe  degree  of 
emeticity  appears  to  be  fuliiciently  conftant.  The  cryftals  may 
be  obtained  in  feveral  fucceflive  produdls  by  repeated  evapora- 
tions, 

Macquer  propofed  the  powder  of  algaroth,  as  more  uniform 
in  its  power.  Meffrs.  De  Laffone  and  Durande  have  adopted 
the  opinion  of  Macquer  ;  and  the  celebrated  Bergmann  has  fol- 
lowed the  ideas  of  the  French  chemifts,  with  a  /ew  flight  modi- 
iications. 

Take  five  ounces  of  cream  of  tartar  reduced  into  powder,  and 
two  ounces  two  gros  of  the  powder  of  algaroth  precipitated  by 
liot  water,  walhed  and  dried.  Add  water  to  thefe,  and  boil 
them  gently.  By  filtration  and  evaporation  the  cryftals  of 
emetick  tartar  are  obtained  ;  which  may  be  given  in  the  dofe  of 
three  grains,  without  fatiguing  the  ftomach  or  inteftines. 

The  antimoniated  tartrite  of  pot-afti  cryftallizes  in  trihedraj 
pyramids.  It  is  very  tranfparent,  is  decompofed  on  the  fire 
^with  crackling,  and  leaves  a  coaly  refidue.  Sixty  parts  of  water 
<iiffolve  it.  It  efflorefces  in  the  air,  and  becomes  farinaceous. 
The  folutions  of  this  fait  throw  down  a  mucilage,  which  fixes, 
and  forms  a  pellicle  of  confiderable  thicknefs .:  it  is  the  mucil-f 
age  of  cream  of  tartar,  which  is  infoluble  in  water,  and  partly 
foluble  in  alcohol.  The  fulphurick  acid  blackens  it,  but  does 
not  i^felf  become  coloured  till  after  a  long  time.     The  nitiick 


Antimonlal  Preparatiotir,  303 

2tid  diffolvcs  it  partly  ;  and  is  itfelf  decompofed,  with  the  emif- 
fion  of  much  nitrous  gas. 

The  alkalis  and  lime  decompofe  the  antimoniated  tartrite  of 
pot-afli.  Antimony,  properly  mixed  with  the  nitrate,  decom- 
pofes  that  fait  completely.  Equal  parts  of  the  femi-metal  and 
rtitre  being  thrown  into  an  ignited  crucible,  the  fait  detonates^ 
its  acid  is  decompofed  ;  and' at  the  end  of  the  operation  the  cru- 
cible is  found  to  contain  the  alkali  which  ferved  as  the  bafe  of 
the  nitrate,  and  the  antimony  reduced  to  the  (tatc  of  white  ox- 
ide :  this  is  called  Diaphoretick  Antimony.  The  fame  prepar- 
ation may  be  made  by  iifing  the  fulphure  of  antimony  ;  in  which 
cafe  three  parts  of  the  nitrate  are  ufed  to  one  of  the  crude  anti- 
mony. The  refidue  in  the  crucible,  after  the  detonation,  is 
compofed  of  the  oxide  of  antimony,  fixed  alkali,  a  portion  of 
the  nitrate  not  decompofed,  and  a  fmall  quantity  of  fulphate  of 
pot-afh.  This  compound  is  dill  known  by  the  name  of  the  Sol- 
vent of  Rotrou.  Water  deprives  it  of  all  the  lalts  it  contains  ; 
and  leaves  only  the  oxide  of  antimony,  which  is  called  A¥afhed 
Diaphoretick  Antimony.  If  a  fmall  quantity  of  acid  be  pour- 
ed on  the  fluid  which  holds  the  falts  in  folution,  a  fmall  portion 
of  the  oxide  of  antimony  falls  down,  which  was  dilTolved  by  the 
alkali  of  the  nitre.  The  precipitate  forms  the  cerufe  of  antimo- 
rty,  or  the  pearly  matter  of  Kerkringius. 

Equal  parts  of  the  fulphure  of  antimony  and  of  nitrate,  de- 
tonated in  an  ignited  crucible,  form  the  liver  of  antim.ony  or 
fulphurated  oxide  of  antimony  ;  which,  when  pulverized  and 
wafhed,  produces  the  faffron  of  metals,  or  crocus  metallorum. 

The  oxides  of  antimony  have  been  confidered  as  very  diffi- 
cult of  reduflion  -,  and  it  was  not  without  furprize  that  I  at  firfl: 
obferved  the  facility  with  which  they  are  all  reducible  by  the 
black  flux.  This  prejudice  was  eftabhflied  and  propagated  for 
want  of  proper  experiments. 

The  alkalis  do  not  fcnfibly  aft  upon  antimony:  but  the  ful- 
phures  of  alkali  diflblve  it  completely  ;  and  it  is  upon  this  prin- 
ciple that  an  operation  is  founded  by  which  we  obtain  a  valuable 
remedy,  known  by  the  name  oF  Kermes  Mineral,  to  diflinguifh 
it  from  the  vegetable  kermes  ufed  in  dying.  The  preparation  is 
(imply  a  red  fulphurated  oxide  of  antimony.  This  remedy,  firft 
pointed  out  by  Glauber,  who  made  it  with  antimony  and  the  fo- 
lution of  nitre  fixed  by  charcoal,  is  indebted  for  its  celebrity  to 
the  wonderful  cures  it  performed  in  the  hands  of  Simon,  a 
Chartreux  friar  j  whence  it  obtained  the  name  of  the  Powder 
of  the  Chartreux.  This  religious  man  obtained  the  compofition 
from  a  furgeon  named  Laligerie,  to  whom  it  had  been  given  by 
Mr.  Chaftenay,  lieutenant  at  Landau.     Mr.  Dodart,  firll  phyfi- 


304  Antimoinal  P reparations . 

cian  to  the  kino:,  bought  the  fecret  in  the  year  17205  and  Mf* 
Laligerie  rendered  it  pubHck.  According  to  his  procefs,  the 
pounded  fulphure  of  antimony  is  boiled  for  two  hours,  with  one 
fourth  of  its  weight  of  the  folution  of  fixed  nitre  or  pot-afh,  in 
twice  its  weight  of  very  pure  water.  After  ebullition  the  fluid  is 
filtered  ;  the  kermes  falls  down  as  it  cools,  and  is  afterwards 
dried.  Laligerie  dire(fts  that  more  of  the  folution  of  fixed  nitre 
be  digefted  on  the  metal,  till  it  is  completely  diffolved.  Lali- 
gerie burned  fpirit  of  wine  or  brandy  upon  it.  The  liquor 
which  remains  after  the  Kermes  is  fallen  down,  contains  more 
kermes  which  may  be  difengaged  by  means  of  an  acid.  This 
kermes,  which  is  paler  than  the  former,  is  known  by  the  name 
of  Golden  Sulphur  of  Antimony  or  the  orange-coloured  ful- 
phurated  oxide  of   antimony. 

This  procefs  is  no  longer  ufed.  That  which  fucceeded  the 
beil  with  me,  confifls  in  boiling  tenor  twelve  pounds  of  pure  al- 
kaline folution  with  two  pounds  of  the  fulphure  of  antimony. 
The  ebullition  is  continued  for  half  an  hour  after  which  the  flu- 
id is  filtered  ;  and  much  kermes  is  obtained  by  mere  cooling. 
I  digeft  new  alkali  on  the  antimony,  until  it  is  confumed.  Tlic 
kermes  which  I  obtain  by  this  means  is  of  a  beautiful  tufted  ap- 
pearance 

GeoiFroy,  who  analyfed  the  kermes  in  1734  and  1735,  found 
that  one  gros  of  kermes  contained  from  fixteen  to  feventeen 
grains  of  antimony,  from  thirteen  to  fourteen  grains  of  alkali, 
and  from  forty  to  forty-one  of  fulphur.  But  Meflrs.  Baume, 
Deyeux,  de  la  Rochefoucauld,  and  De  Fourcroy,  are  not  con- 
vinced that  the  wafhed  kermes  contains  an  atom  of  alkali  which 
is  not  neceflary  to  its  virtues. 

Kermes  is  likewife  one  of  thofe  remedies  in  the  preparation 
of  which  th::  greateft  care  ought  to  be  taken.  It  is  neverthelefs 
a  fubftance  which  all  the  apothecaries  in  the  country  buy  at  the 
fair  of  Beaucaire  ;  and  the  analyiis  which  I  have  feveral  times 
made  of  this  kermes,  has  convinced  me  that  it  very  often  is 
nothing  elfe  but  pounded  brick,  mixed  with  vegetable  kermes, 
and  fprinkled  with  a  ftrong  folution  of  emetick  tartar.  I  have 
found  fomc  which  was  mereiy  a  mixture  of  the  fine  brown  red, 
and  the  calx  of  antimony. 

Lime  and  lime-water,  digefled  upon  pulverized  antimony,  af- 
ford, even  in  the  cold,  at  the  end  of  a  certain  time  a  kind  rC 
kermes,  or  golden  fulphur,  of  a  beautiful   red  colour. 

Antimony  enters  into  the  compofitionof  printers'  types.  It  h 
likewife  mixed  with  tin  to  increafe  its  hardnefs.  It  v/as  for- 
merly ufed  as  a  purgative  :  for  this  purpofe  it  was  made  into 
cups,  in  which  water  or  wine  was  fufibred  to  ftand  for  a  night 
and  taken  by  tlic  patient  the  i'oHowing  day. 


CharaSlers  and  Ores  of  Zinc,  305 

The  fulphure  of  antimony  Is  ufed  as  a  fudorifick  in  {kin  dlfor- 
ders.  For  this  purpofe  it  is  tied  in  a  cloth,  and  digefted  in  th<^ 
ptifans  appropriated  to  thefe  diforders.  It  is  adminiilered  ia 
pills  for  the  fame  purpofe. 

The  folvent  of  Rotrou  has  been  much  ufed  to  diflipate  lym- 
phatick  concretions,  and  pitultous  fwellings. 

Wafhed  diaphoretick  antimony  is  ufed  in  confiderabie  dofes 
to  excite  perfpiration.  Some  phyficians  have  confidered  it  as  a 
medicine  void  of  effedl  ;  and  Boerhaave  has  rriaintained  that  its 
cffe6t  is  not  more  confiderabie  than  that  of  Lemnian  earth. 

The  kermes  mineral  is  one  of  the  moft  valuable  medicines  that 
the  healing  art  is  acquainted  with.  It  i^  incifive  ;  and  may  be 
adminiftered  in  all  pituitous  cafes,  when  the  ftomach  fails,  and 
and  the  lungs  are  obftru<Sled.  Ii^a  more  confiderabie  dofe  it  is 
fudorifick,  and  a  ftill  larger  portion  is  emetick.  It  is  employed 
in  the  dofe  of  from  half  a  grain  to  three. 

The  tartar  emetick  has  received  its  name  from  its  ufes.  It  is 
diflblved  in  water ;  and  this  folution  produces  its  effeft. 

The  liver  of  antimony,  crude  antimony,  and  the  crocus  me- 
tallorum,  are  more  efpecially  ufed  as  purgatives  in  the  veterina- 
rian practice.  They  are  given  to  horfes  in  the  dofe  of  about  an 
ounce. 


CHAPTER     VL 

Concerning  Zim. 

ZINC  Is  a  metaliick  fubftance  of  a  blulfh  brilliant  white  col- 
cur,  very  difficultly  reducible  into  powder,  but  capable  of  being 
extended  into  very  thin  plates  by  the  equal  and  gradual  prefTure 
of  the  flatting  mill.  From  this  laft  property,  which  has  been 
proved  by  Mr.  Sage,  we  may  confider  zinc  as  the  intermediate 
fubftance  between  femi-metals  and  metals. 

Zinc  is  ftfund  naturally  in  various  ftates. 

I.  Cronftedt  affirms  that  he  faw  a  radiated  cryftallizatlon  of  a 
metaliick  appearance,  which  is  found  at  Schneeburg,  where  it  is 
called  flowers  of  bifmuth,  but  which  he  found  to  be  the  regulus 
of  zinc.  This  celebrated  mineralogift  does  not  venture  to  pro- 
nounce that  it  is  native  zinc. 

Mr.  Bomarc  affirms  that  he  found  it  in  fmall  pieces  in  the 
mines  of  lapis  calaminaris  in  the  duchy  of  Limbourg,  and  in 
the  zinc  mines  of  Goflar.  This  regulus  may  have  arifen  from 
the  fcorise  of  furnaces,  or  from  the  ancient  works ;  fo  that  the 
€xiftence  of  native  zinc  is  ftill  confidered  as  very  doubtful  by 
thefc  mineralogifts. 
2...P 


3o6  Ap^  of  Blende,    Ores  of  Zinc. 

2>  Zinc  IS  ufaally  mineralised  by  fulphur,  forming  an  o'rc 
known  by  the  name  df  Blende,  which  in  German  flgnifies 
blinding  or  deceitful ;  a  name  which  may  have  been  given  to  it 
becaufe  fuch  diftri£ls  as  abound  with  this  mineral  are  barren  of 
other  ores. 

The  determinate  cryftallization  of  blende  appears  to  be  the 
aluminiform  oftahedron,  and  fometimes  the  tetrahedron  \  but 
the  modifications  of  thefe  primitive  forms  are  fo  numerous,  that 
the  cryftals  are  found  in  an  aflonlfhing  variety  of  figures.  Moft 
Commonly  they  are  polyhedral  cryftals  of  an  indeterminate  form, 
or  fcarcely  capable  of  being  defcribed.  On  this  circumftance 
depend  the  denominations  of  Blende  with  Large  or  Small  Plates, 
Striated  Blende,  Compa6l  Blende,  and  other  fpecies,  which  may 
be  feen  in  the  works  of  Meffiip.  Sage,  De  Lille,  &c. 

The  colour  of  thefe  blendes  is  infinitely  various;  they  are 
found  yellow,  red,  black,  femi-tranfparent,  &c. 

All  the  blendes  emit  an  hepatick  fmell  when  grated  or  tritu- 
rated. 

There  is  a  kind  of  blende  which  exhibits  a  line  of  phofphorlck 
flame  when  fcratched  with  a  knife,  or  even  with  a  tooth-pick. 
Mr.  De  Bournon  found  this  yellowifli,  tranfparent,  and  phof- 
phorick  blende,  fimilar  to  that  of  ScharfFenburg,  at  Maronne  in 
the  mountains  of  Oifan,  at  the  diftance  of  nine  leagues  from' 
Grenoble.     The  phofphorick  blende  contains  fcarcely  any  iron. 

To  make  the  affay  of  a  blende,  Mr.  Monnct  advifes  folution  of 
the  ore  in  aqua  fortis.  The  acid  unites  with  the  metal,  and  fep- 
arates  the  fulphur  :  after  which  the  oxide  of  Zinc  may  be  ob* 
tained  by  diililiing  off  the  acid  ;  and  this  may  be  reduced. 
Bergmann  obtains  one  part  of  the  fulphur  of  thefe  ores  by  dif- 
tillation,  diffolves  the  refidufe  in  ax:idS)  and  precipitates  the  met- 
al from  its  folutions.  Mr.  Sage  diftils  blende  with  three  part* 
of  fulphurick  acid  :  the  fulphur  fublimes  by  this  operation  •,  and 
the  refidue  in  the  retort  is  the  fulphate  of  zinc,  mixed  with  a 
fmall  quantity  of  fulphate  of  iron,  and  other  fubftances  mixed 
with  the  zinc.  I  do  not  know  any  cou^ntry  where  blende  is 
wrought  to  obtain  the  zinc ;  but  it  is  fometilnes  mixed  with 
lead  ;  and  in  the  working  of  this  lad  metal  the  former  is  occa* 
fionally  obtained.  Such  is  the  ore  worked  at  Rammelfburg  near 
Goflar  in  the  lower  Hartz.  Great  part  of  the  zinc  is  diffipated 
during  the  fufion  of  the  lead  ore  ;  but  a  portion  of  this  metal  is 
obtained  by  a  very  ingenious  procefs.  Care  is  taken  to  keep  the 
anteriour  part  of  the  furnace  cool  •,  againll  which  a  ftone  is  plac- 
ed with  a  flight  degree  of  inclination.  The  vapours  of  the  zinc 
which  are  carried  againil  this  ftone,  are  condenfed,  and  fall  in 
drops  into  powder  of  charcoaJ ;    with  which  »  ftone  j^laced  at 


I 


uinalyfa  of  Calamine,  3^^ 

die  bottom  is  covered.  The  femi-metal  is  defended  from  oxi- 
dation by  means  of  the  charcoal ;  and  it  is  ^f|:crwar.ds  fufed  and 
•call  into  convenient  forms. 

This  zinc  is  always  united  with  a  fmall  quantity  of  lead,  and 
is  lefs  pure  than  that  which  comes  to  us  from  India,  under  the 
name  of  Tutenag. 

I  ftrongly  calcined  the  blende  of  St.  Sauveur,  and  mixed  the 
powder  with  charcoal.  I  then  put  the  whole  into  a  retort  whofe 
orifice  was  plunged  benesth  water ;  and  by  a  violent  heat,  kepf 
up  for  two  hours,  1  obtained  .much  zinc^  which  fell  to  the  bot* 
tom  of  the  water. 

3.  The  decompofition  of  blende  gives  rife  to  the  formation  of 
the  fulphate  of  zinc.  The  operation  of  nature  is  flow,  but  ^rt 
has  fupplied  its  defe(3;.  All  the  fulphate  of  zinc  which  is  met 
with  in  commerce,  is  prepared  at  Rammelfburg.  For  this  purpofe 
after  having  roaftcd  the  galena  mised  with  the  blende,  it  is 
thrown  ignited  into  cifterns  full  of  water,  vyhere  it  is  left  for 
twenty-four  hours.  The  roafted  mineral  is  three  times  extin- 
guiflied  in  the  fame  water  ;  after  which  the  lixivium  is  evapo- 
rated, and  put  into  coolers.  At  the  end  of  fifteen  days  the  wa^ 
ter  is  decanted,  in  order  to  feparate  the  eryftals  of  the  fulphate 
of  zinc.  Thefe  cryftals  are  afterwards  fufed  in  iron  veflels  \ 
and  the  liquor  is  poured  into  coolers,  where  it  is  flirred  till  it 
congeals.  We  fhiall  examine  the  properties  of  this  fait  in  due 
courfe. 

4.  Zinc  is  likewife  found  in  the  flate  of  oxide  ;  and  it  ap- 
pears to  me  that  nature  makes  ufe  of  two  means  of  converting  the 
metal  to  this  ftate.  i.  The  fulphur  is  fometimes  dllTipated  with- 
out the  produdion  of  fulphate  ;  in  which  cafe  it  is  replaced  hj 
the  oxigenous  gas,  and  the  refult  is  that  oxide  of  zinc  which  is 
known  by  the  name  of  Lapis  Calaminaris.  I  have  found  ftrataof 
lapis  calaminaris  at  St.  Sauveur,  intermixed  v/ith  layers  of  blende  ; 
and  the  tranfition  of  the  blende  to  the  flate  of  lapis  calaminaris 
may  be  followed  in  the  moll  interefling  manner.  2.  The  ful- 
phate of  zinc  produced  by  the  decompofiiion  of  blende  in  cer- 
tain circumftances,  is  itfelf  decompofed  by  calcareous  ftoneso 
In  the  rich  colledlions  of  MeflVs.  'Sage,  De  Lifle,  &c.  we  fee 
cryftals  of  calcareous  fpar  converted  into  calamine  at  one  end, 
and  calcareous  at  the  other. 

Calamine  cryftallizes  in  rhomboidal  tetrahedral  prifms,  or  in 
hexadral  pyramids. 

It  is  fometimes  covered  with  protuberances  j  often  has  the 
appearance  of  being  worm-eaten  5  and  is,  at  other  times,  either 
Spongy  or  compact. 

Its  colour  varies  greatly.  The  county  of  Spmerfet  affords  it 
9!  whitCj  green,  and  other  colours. 


3o8  Properties  of  Zim. 

To  make  a  good  analyfis  of  calamine,  Bergmann  advifes  fo=- 
lution  in  the  fulphurick  acid  ;  he  obtains  the  fulphates  of  iron 
and  of  zinc.  That  of  iron  is  decompofed  by  a  known  weight 
of  zinc  ,  and  the  metal  is  afterwards  precipitated  by  the  carbo- 
nate of  foda.  He  has  afcertained  that  ninety-three  grains  of 
this  precipitate  are  equivalent  to  one  hundred  grains  of  zinc  ) 
and  from  rhis  weight  he  deducts  that  of  the  zinc  made  ufe  of  to 
precipitate  the  iron. 

Zinc  may  be  obtained  from  calamine  by  diftillation.  For 
this  purpolif  I  have  ufed  the  fame  procefs  as  has  already  been 
inentioned  in  treating  of  blende. 

Z.nc  yields  beneath  the  hammer,  without  extending  itfelf. 
If  it  be  cad  into  fmall  plates,  it  may  then  be  laminated,  and  re^ 
duced  nito  very  thin  and  very  flexible  leaves. 

The  fpecifick  gravity  of  fufed  zinc  is  7,1908.  See  Briflbn. 
Zmc,  when  heated,  may  be  eafily  pulverized.  This  opera* 
tion  is  very  difhcult  without  this  precaution  indicated  by  Mac- 
quer  ;  /or  it  wears  and  choaks  up  files,  and  deftroys  them  in  a 
liiort  time  :  befides  which,  they  have  no  confiderable  aftion  up^ 
on  it.  it  may  like  wife  be  fufed  and  poured  into  water. — ^Thefe 
are  the  moil:  convenient  means  of  pulverizing  it. 

Zinc,  treated  in  clofe  veflels,  fublimes  without  decompofition  : 
but  when  it  is  calcined  in  the  open  air,  it  becomes  covered  with 
a  grey  powder,  which  is  a  true  oxide  ;  and,  if  it  be  heated  to 
rednefs,  it  takes  fire,  emits  a  blue  flame  ;  and  white  flocks  ifluc 
from  it.  which  are  called  Philofophical  Wool,  Pompholix,  or 
Nihil  Album.  This  oxide  may  be  fufed  into  glafe  by  an  ex^ 
ceedingly  violent  heat :  the  glafs  is  of  a  beautiful  yellow  colour. 
Zinc  laminated  into  very  thin  leaves,  takes  fire  by  the  flame  of 
a  taper,  and  burns  with  a  blue  colour  mixed  with  green. 

Mr.  De  LaiTone,  who  has  written  feveral  excellent  Memoirs 
on  zinc,  confiders  it  as  a  kind  of  metallick  phofphorus. 

"W  ater  appears  to  have  fome  adlion  upon  zinc.  When  this 
femi-metal  begins  to  be  ignited,  if  water  be  poured  on  it,  the 
fluid  is  decompofed,  and  much  hydrogenous  gas  is  difengaged. 
Mcli'rs.  Lavoiiier  and  Meuifner  have  afcertained  this  fact,  in 
their  line  experiments  on  the  decompofition  of  water. 

Sulphurick  acid  diflblves  it  in  the  cold,  and  produces  much 
liydrogenoub  gas.  A  fait  may  be  obtained  by  evaporation,  in 
tetrahedral  prifmatick  cryftals,  terminated  by  a  four-fidcd  pyra- 
mid. Mr.  Bucquet  has  obferved  that  thefe  prifms  are  rhomboi- 
dal.  This  fait  is  known  by  the  name  of  Vitriol  of  Zinc,  White 
Vitriol,  Sulphate  of  Zinc  :  its  tafl:e  is  confiderably  ftyptick.  It 
is  not  much  altered  by  expofure  to  air  when  pure  ;  but  fuflcKs 
its  acid  to  efcape,  at  a  degree  of  heat  lefs  than  is  required  by  the 
(ulphate  of  iron. 


Habitudes  cf  Zinc,  3C9 

The  nitrick  acid  attacks  zinc  with  vehemence,  even  when  di- 
luted with  water.  In  this  operation  a  great  part  of  the  acid  is 
decompofed  ;  but  if  the  rcfidue  be  concentrated  by  flow  evapo- 
ration, cryftals  are  obtained  in  comprefled  and  ftriated  tetrahe- 
<lral  prifms,  terminated  by  pyramids  with  four  fides.  Mr.  De 
Fourcroy  to  whom  we  are  indebted  for  this  obfervation,  adds» 
that  the  fait  melts  upon  heated  coals,  and  fpreads  abroad  with 
decrepitation,  and  a  fmall  reddifh  flame.  If  it  be  expofed  to 
heat  in  a  crucible,  it  emits  red  vapours,  aflumes  the  confiftencc 
of  a  jelly,  and  preferves  this  foftnefs  for  a  certain  time.  The  ni- 
trate of  zinc  is  very  deliquefcent. 

The  muriatick  acid  attacks  zinc  with  efFervefcence.  Hydro- 
genous gas  is  produced,  aad  black  flocks  are  precipitated,  which 
fome  chemifts  have  taken  for  fulphur,  others  for  iron,  and  which 
Mr.  De  Laffone  confiders  as  an  irreducible  oxide  of  zinc.  This 
evaporated  folution  becomes  thick,  and  rcfufes  to  crylbllize. 
It  fufters  a  very  concentrated  acid  to  efcape  when  heated,  and 
the  muriate  itfelf  fublimes  by  dillillation. 

The  pure  alkalis  boiled  on  zinc  obtain  a  yellow  colour,  and 
diflblve  a  part  of  the  metal,  as  Mr.  De  Lafl^one  has  proved. 
Ammoniack  digefted  in  the  cold  upon  this  femi-metal,  difen- 
gages  hydrogenous  gas  :  this  evidently  arifes  from  the  decom- 
pofition  of  the  water,  which  alone,  and  without  any  mixture,  is 
decompofed  upon  ignited  zinc,  as  we  have  already  obferved. 

Zinc  mixed  with  the  nitrate  of  pot-a(li,  and  thrown  into  an 
ignited  crucible,  caufes  this  fait  to  detonate  llrongly. 

Zinc  decompofes  the  muriate  of  ammoniack  by  limple  tritur- 
ation, according  to  Mr.  Monnet. 

Pott  has  obferved  that  a  folution  of  alum,  boiled  upon  the 
filings  of  zinc,  is  decompofed,  and  affords  the  fulphate  of   zinc. 

Zmc  fufed  with  antim.ony,  forms  a  hard  and  brittle  alloy. 

It  unites  with  tin  and  copper,  and  forms  bronze  •,  when  com- 
bined with  copper  alone,  it  forms  brafs. 

It  is  mixed  with  gunpowder,  to  produce  the  white  and  bril- 
liant ftars  of  artificial  fire- works. 

It  has  been  propofed  to  fubilitute  this  metal  in  the  room  of 
tin,  for  the  internal  lining  of  copper  veflels  ;  and  it  is  afcertain- 
ed  from  the  labours  of  Mr.  Malouin,  that  this  covering  would 
be  more  uniformly  extended  upon  the  copper,  and  would  be 
harder  than  tin.  It  has  been  remarked  that  vegetable  acids 
might  diflbJve  it,  and  that  ihefe  fults  are  dangerous  ;  but  Mr. 
de  la  Planclie  has  made  all  the  experiments  on  this  fubjecfl  which 
his  extenfive  knowledge,  and  zeal  for  the  publick  good  could  in- 
fpire  ;  and  he  is  convinced  that  the  falts  of  zinc,  taken  in  a 
more  confiderable  dofe  than  the  aliments  prepared  in  vefl^els  tin- 
ned with  this  femi-metal  might  conrain,  are  not  dangerous. 


310  Manganefe, 

The  fuyimed  oxide  of  zinc  is  much  employed  by  the  Oer* 
man  phylkians,  under  the  nanae  of  Flowers  of  Zinc.  This 
remedy  is  given  as  an  antifpafmodick.  It  may  be  adminiftered 
in  pills,  in  the  dofe  of  one  grain.  Tutty,  or  pompholix,  is  mix- 
ed with  frefli  butter,  as  an  excellent  remedy  in  diiorders  of  the 
eyes. 

Mr.  De  Morveaux  lias  fubftituted  the  precipitate  of  zinc  to 
white  lead,  wuh  the  greateil  advantage.  It  perfectly  anfwers 
the  intention  of  the  artift,  and  is  not  attended  with  any  daa^ 
gerous  cpnlequences  in  its  ufe. 


CHAPTER    VIL 

Concerning   Manganeje, 

A  MINERAL  of  a  grey  or  blackifh  colour,  foiling  the  fen-? 
gers,  and  ufed  in  glafs-boufes  under  the  name  of  8oap  of  the 
Glafs-makers,  has  been  long  known  in  commerce.  Mod  nat- 
uralifts,  fuch  as  Henckel,  Cramer,  Gellert,  Cartheufer,  and  Wal- 
lerius,  have  placed  it  among  the  iron  ores.  Pott  and  Cronftedt 
did  not  confider  it  as  a  ferruginous  fubftance.  The  latter  found 
it  to  contain  tin  j  and  Mr.  Sage  was  long  of  opinion  that  it  was 
an  intimate  alloy  of  zinc  and  cobalt. 

The  celebrated  Bergmann,  in  the  year  1764,  declared  in  prints 
that  black  manganefe  ought  to  contain  a  peculiar  metal  ;  but 
he  attempted  in  vain  to  extraft  it.  However,  Mr.  Gahn,  a  phy* 
fician  at  btockholm,  fucceeded  in  obtaining  a  metal  by  the  affilt- 
2nce  of  an  exceedingly  ftrong  fire.  We  Ihall  explain  his  procefs 
after  having  fpoken  of  the  different  forms  under  which  manga- 
nefe is  found  in  the  earth. 

Manganefe  appears  to  be  always  found  in  the  flate  of  oxide  ; 
but  this  oxide  exhibits  feveral  varieties. 

1.  It  is  fometimes  grey,  brilliant,  and  cryftallized,  formed  of 
very  (lender  prifms  confufedly  intertwined,  and  refembling  the 
ore  of  antimony  ;  from  which  however  it  may  be  eafily  diftin- 
guiflied  by  expofing  it  upon  charcoal.  For  antimony  fules,  and 
affords  vapours  ;  but  the  manganefe  remains  unchanged. 

The  cryftals  of  manganefe  are  (Iriated,  tetvahedral,  rhomboi- 
dal  prifm.s,  terminating  in  four-fided  pyramids.  They  fre- 
<]ueniJy  diverge  from  a  centre. 

2.  Manganefe  is  very  often  black  and  friable.  This  fpecies 
is  found  in  the  cavities  of  the  brown  hsematites  pf  the  Pyrei^e» 
an  Mountains. 


Ores  of  Manganep,  3,11 

I  have  difcovered  shi  ore  at  St.  Jean  de  Gardonenque,  in  the 
Cevennes.  it  is  prodigioully  light,  is  found  in  ftrata,  and  iti 
pieces  which  almofl  always  have  the  figure  of  an  hexahedral 
prifm,  eighteen  lines  in  length,  and  thirteen  or  fourteen  in 
thicknefs. 

This  ore,  upon  which  I  have  made  experiments  that  I  (liaH 
{>Tefently  recite,  is  the  pureft  and  fineft  I  am  acquainted  with. 

3.  Manganefe  is  fometimes  of  a  reddifh  white  colour,  and 
compo&d  of  groups  of  protuberances.  Its  fra£ture  is  lamellated. 
That  of  Piedmont  frequently  has  a  grey  reddifli  tinge,  and  ap- 
pears to  be  compofed  of  fmall  plates.  It  gives  fire  with  the 
fteel. 

The  Manganefe  of  Macon  in  Buf gundy  15  of  a  deeper  grey 
than  that  of  Piedmont. 

That  of  Perigueux  is  intermixed  with  yellow  martial  ochre. 
it  is  found  in  Separate  bodies,  and  not  in  veins  like  that  oi  Pied- 
momt. 

4.  Moft  of  the  white  fpathofe  iron  ores  contain  manganefe, 
and  may  be  confidered  as  ore's  of  this  femi-metal.  Manganefe 
is  likewife  mixed  with  calcareous  fpar,  gypfum^  jafper,  haema- 
tites, &c.  Mr.  De  la  Peroufe  has  defcribed  thirteen  varieties  of 
cryftallized  manganefe  found  in  the  Pyrenean  Mountains — See 
the  Journal  de  Phy£que,  Jan.  1780,  p.  6/. 

5.  Scheele  has  proved  that  the  afnes  of  vegetables  contain 
manganefe ;  and  it  is  to  this  mineral  that  the  colour  of*calclned 
pot-a{h  is  owing.  To  extradl  it,  three  parts  of  fixed  alkali,  one 
of  fifted  allies.,  and  one  eighth  of  nitrate,  muftbe  fufed  together. 
The  fluid  mixture  mufl:  then  be  poured  into  an  iron  mortar, 
where  it  congeals  into  a  greenifh  mafs.  This  being  pounded, 
and  boiled  in  pure  water,  mud  be  filtrated,  and  faturated  with 
fulphurick  acid.  At  the  end  of  a  certain  time,  a  brown  powder 
is  depoTited,  which  pofleiTes  the  properties  of  manganefe. 

To  reduce  manganefe  to  the  metalllck  flate,  a  crucible  Is  lirr- 
ed  wich  charcoal  5  and  into  a  hole  made  in  this  charcoal,  a  ball 
of  manganefe,  prevloufly  kneaded  with  oil  and  gum  ammoni- 
ack,  is  to  be  put  \  after  which  the  hole  is  to  be  covered  with 
powder  of  charcoal.  xA.nother  crucible  mufi:  then  be  fitted  on, 
and  the  veflel  expofed  to  a  violent  fire  for  an  hour  and  a  half. 
By  following  this  procefs,  I  have  feveral  times  obtained  the 
metal  from  the  oxide  of  manganefe  of  Cevennes.  I  have  event 
fucceeded  in  reducing  It,  by  fimply  putting  the  powder  of  man- 
ganefe into  a  lined  crucible. 

The  button  which  Is  obtained  almoft  always  has  afperities  on 
its  furface.  Globules  appear  wliich  fcarcely  adhere  to  the  mafs  ; 
and  thefe  portions  are  ufually  of  a  confiderably  deep  green,  while 
die  internal  pa¥t  has  a  bluiih  caf!. 


312  Pure  Air  of  Manganefe 

This  metal  is  more  infufible  than  iron.  I  have  feveral  times 
obferved,  when  the  fire  has  not  been  fuificiently  ftrong  to  fufc 
the  manganefe,  that  (everal  globules  of  iron  have  appeared  dif- 
perfed  through  the  agglutinated  oxide. 

Saline  fluxes  ought  to  be  rejected,  as  infufficient  for  this  re- 
du£tion.  The  great  difpofition  which  this  femi-metal  has  to 
become  vitrified,  caufes  it  to  be  difperfed  in  the  flux,  where  it 
remains  fufpended.  I  have  feveral  times  by  ufing  the  vitreous 
flux  of  Mr.  De  Morveau,  obtained  metallick  grains  forming  a 
button,  orelfe  difperfed  in  the  flux  ;  which,  when  more  narrow- 
ly examined,  proved  to  be  nothing  but  iron,  cobalt  or  other  met- 
als, according  to  the  nature  of  the  ore  of  manganefe.  I  have 
fometimcs  obtained  even  globules  of  lead  ;  becaufe  the  coarfeft 
glafsin  which  the  prefence  of  that  metal  is  the  lead  fufpefted, 
and  which  enters  into  the  compofition  of  the  flux  of  Mr.  Dc 
Morveau,  contains  it  very  often. 

The  fpecifick  gravity  of  manganefe  has  been  efl:imated  by 
Bergmann,  in  proportion  to  that  of  water,  nearly  as  6850  to 
1000. 

The  oxide  of  manganefe,  when  ftrongly  heated  in  clofe  vefl'- 
cls,  affords  a  prodigious  quantit)^  of  oxigenous  gas,  and  begins 
to  afford  it  at  a  degree  of  heat  lefs  than  is  neceiiary  to  difengage 
it  from  the  oxides  of  mercury  :  a  flrong  fire  is  required  to  difen- 
gage the  laft  portions.  Four  ounces  of  the  manganefe  of  Cev- 
ennes  afforded  me  nine  pints  of  oxigenous  gas.  The  refidue 
in  the  retort  was  a  grey  oxide  ;  one  part  of  which  was  incruft- 
ed  in  the  fufed  glafs,  and  had  communicated  to  it  a  very  rich  vi- 
olet colour. 

The  oxide  of  manganefe,  diflilled  with  charcoal,  aflbrds  the 
carbonick  acid  ;  but,  if  it  be  calcined  in  an  open  vefTel,  it  is  re- 
duced into  a  grey  powder,  which  lofes  confiderable  of  its  weight 
when  the  fire  is  very  ftrong  j  and  at  length  agglutinates,  and 
forms  a  green  mafs. 

If  it  be  mixed  with  charcoal,  it  does  not  fufFer  any  perceptible 
change  in  its  colour. 

Manganefe,  expofed  to  a  very  violent  heat,  vitrifies,  and  af- 
fords a  glafs  of  an  obfcure  yellow  colour.  The  iron  which  is 
mixed  with  it  preferves  its  metallick  form. 

Manganefe  is  eafily  changed  in  the  air,  and  is  refolved  into 
a  brown  powder  of  a  greater  weight  than  the  femi-metal  itfelf  ; 
a  certain  proof  of  oxidation. 

Manganefe  unites  eafily  by  fufion  with  all  the  metals  except 
pure  mercury.  Copper  alloyed  with  a  certain  quantity  of  man- 
ganefe is  ftill  very  malleable. 


Hudiometer  lulth  Mangatiefe.  ^  X  ^ 

If  a  mixture  of  the  phofphate  of  urine  with  a  fmall  quantity 
of  oxide  of  manganefe  be  placed  upon  charcoal,  and  be  kept  in 
fufion  for  a  few  inflants  by  means  of  the  blue  interiour  flams  o£ 
the  blow-pipe,  a  tranfparent  glafs  will  be  produced,  of  a  blue 
colour  inclining  to  red  ;  which,  when  charged  with  a  certain 
quantity  of  the  fait,  aOUmes  the  colour  of  a  ruby.  If  it  be  kept 
in  fufion  for  a  longer  time,  a  flight  efl'ervefcence  is  perceived, 
and  all  the  colour  difappears.  If  the  tranfparent  globule  be  then 
foftened  by  the  exteriour  flame,  the  colour  foon  returns,  and. 
may  be  again  effaced  by  keeping  up  the  fufion  for  a  time.  The 
fmalleft  portion  of  nitrate,  added  to  the  glafs,  immediately  re- 
(tores  the  red  colour  ;  and,  on  the  contrary,  it  is  deflroyed  by 
the  addition  of  fulphurlck  falts.  This  globule  of  glafs,  taken 
from  the  charcoal^  and  fufcd  in  the  fpoon  of  perfect  metal,  be- 
comes red,  and  changes  no  more.  Thefe  experiments  were 
made  by  the  cekbrared  Bergmann. 

The  fulphurick  acid  attacks  manganefe,  and  produces  hy- 
drogenous gas.  This  metal  is  d'lfolved  more  flowly  than  iron  ; 
a  fmell  is  difengaged  fimilar  to  that  which  is  aflbrded  by  the  fo- 
lution  of  iron  by  the  muriatick  acid.  The  folution  is  as  colour- 
lefs  as  water,  and  afix)rds  by  evaporation  tranfparent  colourlefs 
cryftals  in  the  form  of  parallelopipeds,  and  of  a  bitter  tafte. 
Mr.  Sage  obtained  them  in  tetrahedral  prifms,  terminated  by 
four-fided  pyramids.     This  fait  efflorefces  in  the  air. 

If  the  fulphurick  acid  be  poured  on  the  oxide  of  manganefe, 
and  its  aftion  aflilled  by  a  gentle  heat,  an  allonifhing  quantity 
of  oxigenous  gas  is  difengaged.  The  oxide  of  manganefe  of 
Gevennes  afibrded  me  five  pints  and  a  half  per  ounce.  "When 
this  oxide  is  deprived  of  its  oxigene,  the  refidue  is  a  white  pow- 
der, foluble  in  Vv'ater,  which  by  evaporation  affords  the  fulphate 
of  manganefe,  already  defcribed. 

The  celebrated  liergmann  has  obferved  that  coaly  matter, 
fuch  as  fugar,  honey,  and  gum,  ajfifled  the  adHon  of  the  acid. 
This  depends  on  the  combination  of  the  oxigene  with  thefe  a- 
gents,  to  form  the  carbonick  acid  ;  and  the  fulphurick  acid  a^s 
more  eafily  upon  the  metal  itfelf. 

Manganefe  is  precipitated  from  its  folutions  by  the  alkalis,  in 
the  form  of  a  u-hitifh  gelatinous  matter  ;  but  this  precipitate 
foon  lofes  its  colour,  and  becomes  black  by  the  contacfl:  of  the 
air.  This  phenomtnoi},  which  I  have  myfelf  been  witnefs  to 
can  be  attributed,  in  my  opinion,  only  to  the  abforption  of  ov- 
igenous gas  :  and  I  wais,  convinced  of  this  truth  by  agitating  the 
precipitate  in  bottles  filled  with  this  gas  \  for  in  this  fituation 
the  black  colour  is  produced  in  one  or  two  minutes,  and  a  con- 
siderable part  of  the  gas  is  abforbed.     I  have  conltruf!:ed  en  eudi- 

2...CL 


3 1  if  Habitudes  of  Mauganefi 

ometer  as  certain  and  as  invariable  as  that  which  the  liquid  ful- 
phure  of  potafh,  or  folutioii  of  liver  of  fulplmr,  affords  ;  but  a 
large  quantity  of  precipitate  is  required  which  mull  be  agitated 
againft  the  fides  of  tiie  veffels,  in  order  that  it  may  prefent  a 
greater  furface  to  tlie  air,  and  that  the  abforption  may  be  more 
fpeedy.  I  judge  of  the  abforption  by  .caufing  the  veffel  to  com^ 
municate,  by  a  graduated  tube,  w^ith  (landing  water.  The  af* 
cenfion  of  this  water  in  the  tube  is  proportionate  to  the  volume 
of  oxigenous  gas  abforbed. 

The  nitrick  acid  diflblves  manganefc  with  effervefcence. 
There  always  remains,  a  black,  fpongy,  and  friable  body,  whick' 
exhibited  to  Bergmann  all  the  chara6lers  of  molybdena.  Other 
folvents  preCented  a  finiilar  refidue.  The  folution  of  the  nitrate 
of  manganefe  has  frequently  a  dull  colour,  and  affumes  the  red- 
colour  with  difficulty.  This  folution  does  not  afford  folid  cryf- 
tals,  even  by  flow  evaporation. 

The  oxide  of  manganefe  is  foluble  in  the  nitrick  acid.  It  is 
obfervable  that  this  acid  is  not  decompofed  upon  them;  becaufe 
it  finds  the  metal  in  the  ftate  of  oxide,  Carbonick  acid  is  affords 
ed  when  coaly  fubllances  arc  added  to  affifl  the  folution.  When 
the  nitrous  or  fuming  nitrick  acid  is  ufed,  the  foKuion  is  made 
without  the  affiftance  of  thefe  coaly  fubftances,  becaufe  the  ex- 
cefs  of  nitrous  gas  fcizes  the  oxigene  of  the  oxide.  Thefe  foiu- 
tions  do  not  cryftallize. 

The  muriatick  acid  diffolves  manganefe  •,  but  when  it  is  ^'i- 
gefted  upon  the  oxide  it  feizes  the  oxigene,  and  paffes  in  vapour 
through  the  water.  This  vapour  is  known  by  the  name  of  Ox- 
igenated  Muriatick  Acid,  whofe  properties  we  have  already  ex- 
plained. 

The  refidue  in  the  retort  confifls  of  a  portion  of  acid  combin, 
ed  with  the  manganefe.  This  by  evaporation  affords  a  faline 
mafs,  which  attracts  the  humidity  of  the  air. 

The  fluorick  acid  with  manganefe  affords  a  fait  of  fparing  fol- 
nbility,  and  this  acid  diffolves  but  little  of  it  :  but  by  decompo- 
fmg  the  fulphate,  the  nitrate,  or  the  muriate  of  manganefe  by 
the  fluate  of  ammoniack,  a  fluate  of  manganefe  is  precipitated. 
The  fame  phenomenon  takes  place  with  the  phofphorick  acid. 
The  acetous  acid  has  but  a  weak  aclion  upon  this  fubtlance.  If 
it  be  digefled  upon  the  oxide  of  manganefe,  it  acquires  the  prop- 
erty of  diffolving  copper,  and  forms  the  beautiful  acetate  of  cop- 
per, or  cryllals  of  Venus  ;  whereas  tlie  fame  acid,  digelled  on 
copper,  forms  verdigris,  or  fimply  corrodes  it.  This  circum- 
(lance  proves  that  the  acetous  acid  becomes  charged  with  ovi- 
genous gas,  by  the  affiltance  of  wliich  it  diffolves  the  copper* 


*with  various   Bodies,  315 

The  oxalick  gcid  not  only  diflolves  manganefe,  but  like- 
wife  the  black  oxide  of  manganefe.  The  faturated  folution  de- 
pofites  a  white  powder,  if  there  be  not  an  excefs  of  acid.  This 
fait  is  blackened  by  the  fire,  but  eafily  refumes  the  milky  colour 
in  the  fame  acid.  The  oxalick  precipitates  it  in  the  form  of 
finall  cryftalline  grains,  when  poured  into  folutions  made  by  the 
fulphurick,  nitrick,  or  muriatick  acids. 

The  acidulous  tartrite  of  pot-afh  diHblves  the  black  oxide, 
even  in  the  cold.  The  tartrite  of  pot-afh  added  to  any  folution 
whatever  of  manganefe,  occafions  a  precipitate  which  is  a  true 
-tartrite  of  manganefe. 

The  carbonick  acid  attacks  manganefe  and  the  ^black  oxide- 
The  folution  becomes  covered  in  the  open  air  with  a  pellicle, 
which  Gonfifts  of  manganefe  that  is  feparated  and  oxided.  It  is 
white  when  it  does  not  contain  iron. 

If  the  muriate  of  ammoniack  be  diftilled  with  this  oxide  of 
manganefe,  an  elaftick  fluid  isdifengaged,  according  to  the  ob- 
:fervation  of  Scheele,  which  he  confiders  as  one  of  the  princi- 
ples of  ammoniackj  .without  determining  its  nature.  Mr.  Ber- 
thollet  has  proved  that,  when  ammoniack  is  difengaged  by  a 
metaUick  oxide,  there  is  a  portion  decompofed.  The  oxigene 
of  the  oxides  unites  to  the  hydrogenous  gas  of  the  alkali  to  form 
water,  and  the  nitrogene  gas  efcapes. 

Eight  parts  of  oxided  manganefe  take  up  by  a  gentle  heat,  in 
a  glafs  retort,  three  parts  of  fulphur  j  and  produce  a  mafs  of  a 
greenifti  yellow. colour,  whicli  acids  attack  with  an  efFervefcencc 
and  hepatick  fmell. 

Manganefe  itfelf  does  not  appear  to  combine  with  fulphur. 
In  order  to  feparaie  iron  from  manganefe,  the  alloy  muil  be 
difTolved  in  the  .nitrick  acid,  and  evaporated  to  drynefs.  The 
refidue  mufl:  be  ftrongly  calcined,  and  digefted  with  weak  ni- 
trick acid,  and  a  fmall  quantity  of  fugar.  The  acid  takes  up  the 
manganefe,  which  may  be  precipitated  by  the  carbonate  of 
pot-afli. 

The  alloy  rhay  like  wife  be  put  into  a  folution  of  the  fulphate 
of  iron.  The  aeid  abandons  the  i/on  to  unite  with  the  manga- 
nefe. 

The  iron  having  lefs  affinity  with  the  acid  than  the  manganefe^ 
may  likewife  be  precipitated  by  a  few  drops  of  alkalki. 

The  oxide  of  manganefe  is  chiefly  ufed  in  glafs-houfes,  to 
deprive  glafs  of  its  green  or  yellow  colour,  which  foda  and  fand, 
when  fufed  together,  ufually  alfumc.  It  has  on  this  account 
been  called  the  Soap  of  the  Glafs-makers.  It  is  alfo  ufcd  to 
colour  glafs  and  porcelain  of  a  violet  colour. 


3 1 6  CharaBers  of  Lead. 

The  confumption  of  this  mineral  is  become  more  confiderable 
lince  the  difcovery  of  the  oxigenated  muriatick  acid,  which  haq 
pointed  out  its  ufes  in  bleaching  of  linen,  cotton.  Sec. 


CHAPTER    VIIL 

Concerning  Lead. 

LEAD  is  the  fofteft,  the  leaft  tenacious,  the  lead  fonorous, 
the  leaft  elaftick,  and  one  of  the  moft  ponderous  of  metals.  A 
cubick  foot  of  lead  weighs  feven  hundred  and  ninety-four 
pounds,  ten  ounces,  four  gros,  forty-four  grains.  Its  Ipecifick 
gravity  is  to  that  of  water  as  1 15523  to  loooo,  according  to  Brif^ 
ion.  Its  fracture  is  of  a  bluiOi  white  colour,  darker  than  that  of 
tin,  and  tarniftiing  in  the  air.  It  poffefles  a  peculiar  fmell, 
which  is  rendered  perceptible  by  fri(ftion. 

A  gentle  heat  is  fufficient  to  fufe  lead  ;  and  the  abbe  Mongez 
obtained  it  in  cryftals  of  the  form  of  quadrangular  pyramids,  re- 
cumbent on  one  fide.  Some  authors  affirm  that  lead  is  occa- 
fionally  met  with  in  the  native  ftate.  Wallerius  mentions  three 
pieces  of  this  kind.  The  German  mineraiOgifts  likewife  affirm 
that  it  has  been  found  native  in  Viilach  in  Carinthia.  Mr. 
Genflane  found  in  Vivarais,  in  four  places,  at  Serremejanes,  at 
Payet  near  Argcntlere,  at  St.  Etienne  de  Boulogne,  and  near 
Villeneuve  de  Berg,  "  grains  of  native  lead,  from  the  fize  of  a 
<«  chefnut  to  an  almolt  imperceptible  degree  of  fmalinefs  ;  they 
<<  are  all  included  in  a  very  ponderous  metallick  earth,  which  is 
<<  precifely  of  the  colour  of  the  afhes  of  beech,  or  of  litharge 
<*  reduced  to  an  impalpable  powder.  This  earth  may  be  cut 
<'  with  a  knife,  but  requires  the  hammer  to  break  it."  He 
found  pieces  which  contained  a  fubitance  limilar  to  a  litharge 
in  their  internal  part. 

Linnaeus  fpeaks  likewife  of  a  native  It-xA  in  cryftals. — Moft 
natural! fts  agree  to  confider  native  lead  as  of  a  very  problemat- 
ical exiftence.  The  various  famples  found  in  cabinets  are  prob- 
ably owing  to  ancient  mine  works.  Time  has  changed  their 
appearance,  and  incrufted  them  with  various  matters,  which 
feem  to  prove  that  they  do  not  owe  their  formation  to  the  ac- 
tion of  fire  ;  and  this  is  the  circuraftance  which  may  have  im- 
pofed  on  certain  naturalifts. 

I.  Lead  is  ufually  mineralized  by  fulphur  ;  and  this  ore  is 
known  by  the  name  of  Galena. 

It  ufually  cryftallizes  in  cubes,  and  in  all  the  varieties  of  that 
figure. 


Various   Ore.?  of   Lead.  oj*^ 

Galena  is  diftinguiflicd  into  feveral  fpecies.  i.  Large  diced 
galena.  i.  Small  diced  galena.  3.  Scaly  or  plated  galena,^ 
4.  Compacl:  gaien.a,  in  imall  brilliant  grams  refembling  fteel. 
it  does  not  appear  to  be  lamel'ated. 

Thefe  dilt.in(fi:ion3  are  more  efpecially  neceflary  to  be  attended 
to,  becaufe  the  ipecles  are  very  different  in  richnels,  and  the  aU 
loy  of  filver,  which  is  infeparabie  from  galena.  In  general,  the 
large  diced  galena  is  poor  in  filver,  and  is  ufed  to  give  a  glaze 
to  pottery,  by  the  name  of  Alquifoux,  or  potters  lead  ore.  That 
which  is  in  i'mall  grains  is  richer,  and  is  wrought  as  a  lead  ore 
containing  fiiver. 

Galena  is  the  only  fpecies  of  lead  ore  which  is  worked  ;  and 
■we  fliall  relate  all  v/e  have  to  fay  concerning  the  working  and 
aflay  of  lead  ores  after  having  fpoken  of  the  other  ores. 

2.  Lead  has  been  found  mineralized  by  the  fulphurick  acid. 
Mr.  Monnec  has  called  this  ore  the  pyritous  lead  ore.  It  is  fri- 
able, dull,  black,  and  almoft  always  cryftallized  in  very  long 
needles,  or  in  (lala^lites.  It  efllorefces  in  the  air,  and  affords  a 
true  fulphate  of  lead.  This  appears  to  be  of  the  nature  of  gal- 
ena :  for  as  the  fulphate  is  not  developed  but  by  the  eillorefcence 
of  the  ore,  it  may  be  concluded  that  the  fulphurick  acid  does 
not  cxift  in  the  virgin  ore  itfelf. 

Lead  mixed  with  iron  is  fometimes  combined  with  the  ful- 
phurick acid.  A  large  quantity  is  found  in  the  ifland  of  Angle- 
fea.  It  cannot  be  reduced  upon  charcoal  with  the  blow  pipe,  but 
it  fufes  into  a  black  glafs. — Dr.  Withering  has  indicated  this 
ore. 

3.  The  carbonick  acid  very  often  mineralizes  lead,  and  ex- 
hibits fome  varieties  which  we  fliall  proceed  to  defcribe. 

A.  The  white  lead  ore. — This  is  almoll  aKvays  found  in  the 
cavities  of  decompofed  galena,  or  in  the  veins  of  powdery  (lone 
containing  galena.  It  is  heavy,  and  frequently  of  a  greafy  col- 
our ;  decrepitates  in  the  fire  ;  and  is  eafily  reduced  by  dillilla- 
tion,  affording  only  water  and  the  carbonick  acid.  Its  form  is 
almoft  always  cryitalline,  but  varies  prodigioully.  The  primi- 
tive form  appears  to  be  a  dodecahedron,  with  ifofccles  triangular 
planes. 

I  have  feen  cryftals  accurately  of  the  form  of  an  hexahcdral 
prifm  fometimes  terminated  by  a  fix-fided  pyramid.  The  ores 
of  St.  Sauveur  in  the  Cevennes  have  afforded  us  this  variety  ; 
Mr.  Sage  poffcffes  white  lead  ore  of  Geroldfeck  cryftallized  in 
cubes. 

V7hite  lead  as  tranfparent  as  flint  glafs  has  been  found  in 
f-ngland  3n<l  in  Siberia. 


3  '  ^  Vnyioiis  X)ies  cf  Lead. 

The  analyfis  of  tlie  white  lead  of  Siberia  afFort^ed  Mr,  Mac- 
quart,  per  quintal,  fixty-feven  parts  lead,  twenty-four  carbonick 
acid,  fix  oxigene,  and  three  water. 

B.  Green  lead  ore. — This  differs  from  the  foregoing  only  in 
the  modifications  produced  by  the  colouring  principle,  which  is 
copper,  according  to  Spielman  ;  and  iron,  according  to  the 
gre'ateft  number  of  chemifts.  ;Its  form  is  ufually  that  of  a  trun- 
cated hexahedron  ;  and  this  ore  is  not  fo  eafily  reduced  as  the 
Vrhite  ore. 

C.  The  black  ore  of  lead. — -Lead  may  retu  rn  to  the  ftate  of 
galena  by  refuming  the  fulphur  it  had  loit  •,  and  this  regeneration 
is  not  rare.  It  is  enough  that  any  hepatick  vapour  ihould  ftrik^ 
the  ore  to  efFe61:  this  converfion.  The  ores  of  Tfchopau  in  Sax- 
ony, and  thofe  of  Huelgoet  in  Lower  Britany,  exhibit  fine  in- 
fla»ces  of  this  pheno  menon . 

The  gradations  or  intermediate  fpecimens  of  thefe  different 

ores,  eflablKh  an  infuiite  number  of  fpecies,  which  the  naturaJift 

can  never  admit  but  as  varieties.     The  tranfition  of  the  white 

lead  ore,  to  the  black  ore  exhibits  gradations  of  colour  which  it 

A\'ould  be  very  fuperliuous  to  defcribe. 

In  the  year  1 766,  Mr.  Lehmann  described  a  new  fpecies  o'f 
lead  ore,  called  Red  Lead.  It  was  found  in  Siberia,  in  the  en- 
virons of  Catherineburg.  Its  cryftals  are  grouped,  and  adherent 
to  quartz,  to  copper  ores,  or  iron  ;  and  fometimes  to  galena, 
with  cryftals  of  white  and  green  lead.  It  is  frequently  ctyif al- 
lized  \%  rhomboidal  tetrahedral  prifms,  fliort,  and  truncated  ob- 
liquely. 

Mr.  Sag$  has  confidered  this  lead  ore  as  a  variety  of  the  pre- 
ceding fpecies,  coloured  by  iron,  of  which  Mr.  Lehmann  has 
j>roved  the  exiftence.  The  abbe  Mongez  thinks  it  is  minerahz- 
ed  bv  the  arsenical  acid. 

Mr.  Macquart  has  given  us  the  mod  valuable  information 
refpecling  the  red  lead  ore  ;  and  has  proved  by  an  accurate 
analyHs  that  it  contains,  in  the  quintal,  lead  thiny-fix,  oxigene 
ihirty-feven,  iron  twenty-five,  and  alumine  two. 

4,  The  phofporick  acid  has  likewife  been  found  naturally 
combined  with  lead.  This  ore,  difcovered  by  Gahn,  owes  its 
green  colour  to  iron.  It  does  not  efFervefce  with  acids.  In  or- 
<ler  to  aflay  it,  it  muPc  be  diliblved  in  the  nitrick  acid  by  the  af- 
fiftance  of  heat,  and  the  lead  may  then  be  precipitated  by  the 
•fulphurick  acid.  The  fupernatant  liquor  being  decanted  off, 
and  evaporated  to  drynefs,  aifords  the  phofphorick  acid. 

This  ore  melts  by  the  blow-pipe,  and  affords  an  opaque  glob- 
ular mafs  without  reduction.  Its  habitudes  v/ith  fluxes  re-- 
femble  thofe  of  lead  and  its  oxides. 


•Ajfaying  of  Lead*  31^. 

Mr.  De  la  Methcrie  has  informed  us  that  Mr.  *  *  *  an  Eng- 
iifli  gentleman,  by  treating  lead  ores  with  the  blow-pipe,  had 
obfcrved  that  there  was  one  whofe  globule  cryftallized  by  cool- 
Mig,  after  having  been  in  perfeft  fudon  ;  and  that  thefe  ores 
were  not  reducible  by  the  biow-pipe.  Me  fufpe£led  they  were 
mineralized  by  the  phofphorick  acid.  Mr.  De  la  Metherie  and- 
tiiis  gentleman  took  feven  ounces  of  the  green  lead  ore  of  Hoffs- 
gruard,  near  Fribourg  in  Brifgaw  ;  which,  when  treated  by  the 
foregoing  procefs,  afforded  them  phofphorick  acid.  The  phof- 
phorick acid  combined  with  minium  afforded  them  a  green 
compound. 

The  decompofition  of  the  ores  which  we  have  defcribed  fre- 
quently affords  the  oxides  of  lead,  or  calciform  ores. 

Thefe  oxides  at  firft  afford  a  powder  which,  being  carried  a- 
long  by  waters,  often  mixes  with  argillaceous,  calcareous,  or 
quart zofe  earths. 

Thefe  oxides  vary  more  particularly  in  their  colour,  which 
affimilates  them  more  or  lefs  perfei&ly  to  cerufe,  mafficot,  or 
minium. 

In  order  to  make  the  affay  of  a  galena,  it  muft  be  pulveriz- 
ed and  torrefied.  The  torrefied  m^leral,  mixed  with  three 
parts  of  black-flux,  rJfbrds  by  fufion  a  metallick  button,  which 
indicates  the  proportions  of  the  lead  in  the    quintal  of  the  ore. 

Bcrgmann  propofes  to  make  the  affay  of  fulphureous  lead 
ores  by  the  nicrick  acid,  which  diffolves  the  lead  and  not  the 
fulphur.  The  folution  is  then  to  be  precipitated  by  the  carbon- 
ate of  foda;  and  one  hundred  and  thirty-two  grains  of  the 
precipitate  are  equivalent  to  one  hundred  of  the  metal. 
If  the  ore  contains  filver,  ammoniack  is  to  be  digelted  on  the 
precipitate,  from  which  it  diffolves  the  oxide  of  filver. 

The  various  operations  to  which  lead  ore  is  fubje£ted  to  ob- 
tain the  lead,  are — i.  It  is  forted,  to  feparate  the  rich  or  pure 
ore  from  the  pulverized  matter,  and  the  gangue  which  contains 
rlo  metal.  2.  The  ore  is  pulverized,  and  its  gangue  feparated  by 
waihing.  3.  The  ore  is  roafted  in  a  reverberatory  furnace,  with 
occafional  agitation,  that  it  may  prefent  all  its  furfaces  to  the  air  \ 
and  when  the  external  part  begins  to  affume  the  form  of  a  pafte, 
it  is  covered  v/ith  charcoal,  the  mixture  is  Itirred,  and  the  heat  in- 
creafed.  The  lead  then  runs  on  all  fides,  and  is  collected  at  the 
bottom  of  the  furnace,  which  is  pierced,  and  permits  the  metal' 
to  flowinto  a  receptacle  properly  defended  by  a  lining  of  charcoal. 

The  fcorire,  which  llill  retain  much  lead  are  fufed  by  a  bialt 
furnace  :  the  lead  is  caff  into  pigs  for  fale. 

To  difengage  the  filver  which  the  lead  may  contain,  it  is  car- 
jiied  to   the  refining  furnace :  wher^,  by  the   untied    energy  of 


320  I^lahufaciure  of  Red  Lead. 

fire,  and  the  wind  of  bellows  dire6led  upon  the  melted  lead,  thd 
metal  is  converted  into  a  yellow  fcaly  oxide,  ca;lled  Litharge* 
This  litharge  is  driven  off  in  proportion  as  it  forms ;  and  the 
filver  remahis  alone  in  the  middle  of  the  cupel.  The  colour 
caufes  a  diltinction  oF  the  litharge  into  litharge  of  gold,  or 
litharge  of  filver.  When  the  litharge  is  fufed  in  contatl:  with 
charcoal,  it  refumes  its  Hate  of  metal  ;  and  the  lead  is  fo  much 
the  better,  in  proportion  as  it  has  been  deprived  of  the  filver  it 
contained.     The  fmalleft  alloy  of  fine  metal  renders  it  brittle. 

Lead  is  fafible  by  a  gentle  heat.  If  it  be  kept  for  fome  time 
in  fufion,  it  b -"comes  covered  with  a  grey  oxide  ;  which,  when  ex* 
pofed  to  a  more  violent  heat  capable  of  keeping  it  ignited,  af- 
fumes  a  deep  yellow  colour,  in  which  (late  it  is  called  MalFicot. 
MalTicot  may  be  converted  into  the  red  oxide,  or  minium,  by 
the  following  procefs.  When  the  lead  is  converted  into  maffi^ 
cot,  it  is  thrown  out  and  cooled  by  pouring  water  upon  it  •,  after 
"wnich  it  is  carried  to  the  mill,  and  ground  into  very  fine  po\vder» 
which  is  waiiied  in  water.  The  particles  of  lead  which  could 
not  be  pulverized  in  the  mill,  remain  in  the  veiTel  v/here  the 
\va{hing  is  performed. 

This  oxide  of  lead  is  fpi*-<jad  out  upon  the  hearth  of  the  furnace 
in  which  it  is  calcined.  Lines  are  drawn  en  its  furface  ;  and  it 
is  ftirred  fror.i  time  to  time,  that  it  may  not  clot  to^^ether  ;  ani 
the  fire  is  kept  up  for  forty-eight  hours.  When  the  minium  is 
taken  out  of  the  furnace,  it  is  put  into  large  fieves  of  wood,  and 
pafied  through  very  fine  net  work,  or  cloth  of  iron  wire,  placed 
over  the  calks  which  receive  the  minium.  We  are  indebted  to 
Meflrs.  Jars  for  this  information,  who  have  given  very  curious 
details  refpecling  the  manufadlories  of  minium  in  the  county 
of  Derby. 

Mr.  GeoPa-oy  was  of  ophiion,  that,  in  order  to  form  minium, 
no  greater  heat  was  required  than  one  hundred  and  twenty  de- 
grees of  Reaumur's  thermometer,  but  this  heat  is  not  adapted 
to  works  on  a  large  fcale  •,  for  in  thefe  the  roof  of  the  furnace 
is  kept  at  a  red  heat.  The  lead  increafes  in  weight  ten  per  cent 
bv  the  calcination. 

All  thefe  oxides,  urged  by  a  flronger  heat,  are  converted  into 
a  yellow  glafs,  fo  very  fufible,  that  it  penetrates  and  deftroys  the 
belt  crucibles.  It  is  ufed  in  glafs-houfes,  on  account  of  its  fufi- 
biiity,  not  only  to  aifill  the  fulion,  but  likewife  to  render  the 
glafs  fofter,  more  ponderous,  of  a  more  un6luous  feel,  and  more 
iufcepiiblc  of  being  cat  and  poiiflied.  Thefe  are  the  rcafons  for 
which  it  is  made  a  part  of  the  compofition  oi  flint  glafs,  and 
cryilal  glafs. 


Habitudes  of  Lead,  3  2 1 

The  oxides  of  lead,  diftilled  without  addition,  afford  oxige- 
nous  gas  by  a  violent  heat. — Prieflly  obtained  it  from  minium, 
part  of  which  was  converted  into  globules  of  metal. 

When  thefe  oxides  are  fufed  with  coaly  matter,  the  raetal  be- 
comes revived. 

The  fulphurick  acid  boiled  upon  lead  affords  much  fulphure- 
ous  acid  ;  and  an  oxide  is  formed,  which  arifes  from  the  com- 
bination of  the  oxigene  of  the  acid  with  the  lead.  A  portion  of 
the  lead  is  neverthelefs  diflblved  ;  for  if  a  fufficient  quantity  of 
water  be  poured  on  the  refidue,  a  very  cauftick  fait  is  obtained 
by  evaporation,  in  tetrahedral  prifms,  foluble  in  eighteen  times 
their  weight  of  water.  This  fulphate  is  decompofed  by  fire, 
lime,  the  alkalis,  &c. 

Very  hot  fulphureous  acid,  poured  into  a  leaden  veflel,  cor- 
rodes and  deftroys  it  inftantly. 

The  concentrated  nitrick  acid  is  readily  decompofed  upon 
lead,  and  converts  it  into  a  white  oxide  ;  but  when  the  acid  is 
weak  it  diflblves  the  metal,  and  forms  cryftals  of  an  opaque  white 
in  the  formof  fegments  of  a  three-fided  prifm.  I  have  fpeci- 
mens  of  the  nitrate  of  lead  in  my  laboratory,  which  poflefs  the 
form  of  truncated  hexahedral  prifms  ;  three  of  the  fides  being 
broader  than  the  others,  and  exa6lly  fimilar  to  thofe  which  Mr. 
De  Fourcroy  obtained  by  infenfible  evaporation. 

This  fait  decrepitates  in  the  fire,  and  is  fufed  with  a  yellow- 
ifh  flame  upon  ignited  coals.  The  oxide  of  lead  becomes  yellow,, 
and  is  reduced  into  globules  or  metal.  Sulphurick  acid  takes 
lead  from  the  nitrick  acid. 

The  muriatick  acid,  aflifted  by  heat,  oxides  lead,  and  dlfToIves 
a  portion.     This  fait  cryftallizes  in  ftriated  hexahedral  prifms. 

This  muriate  is  flightly  deliquefcent.  Lime  and  alk«Jis  de- 
compofe  it. 

The  fame  acid  poured  on  litharge  decompofes  it  inftantly. 
Fifty  or  fixty  degrees  of  heat  are  produced.  The  folution  af- 
fords fine  odlahedral  cryftals,  of  an  opaque  white  colour,  a  ftyp- 
tick  tafte,  and  of  very  confiderable  weight. 

This  fait  decrepitates  on  the  coals  ;  and  when  the  fire  is  in- 
creafed,  its  water  of  cryftallization  efcapes,  and  it  becomes  con- 
verted into  a  mafs  of  a  beautiful  yellow  colour. 

Three  parts  of  water,  at  fifteen  degrees  of  temperature,  dif- 
folve  one  part  ;  and  boiling  water  more  than  its  weight. 

The  pure  alkalis  precipitate  it  in  the  form  of  a  magma,  which 
occafions  a  kind  of  miraculous  mundi. 

The  afiinity  of  the  muriatick  acid  with  the  oxide  of  lead  is  fo 
ftrong,  that  it  is  capable  of  decompofing  all  its   combinations. 
Minium  or  litharge  decompofes   the   muriate  of  ammoniack, 
2.,.R 


^tt  Hahltudni  of  Lea^, 

The  fame  oxidesj  triturated  with  marine  fait,  feparate  the  fod**  ^ 
and  it  is  upon  thefe  fa£ts  that  Mr.  Turner  and  others  have  ef- 
tabiifhed  manufadories  for  procuring  foda  by  the  decompoGion- 
of  marine  fait.* 

The  muriates  of  lead,  calcined  or  fufed,  afford  a  pigment  of 
a  beautiful  yellow  colour.  The  manufaflories  of  foda  have  af- 
forded a  very  confiderable  quautit)?,  which  is  fubftituted  inftead 
0f  the  fine  Naples  yellow. 

4.  The  acetous  acid  corrodes  lead  ;  and  affords  a  white  ox- 
ide known  by  the  name  of  white  lead. 

To  prepare  this  colour,  the  led  is  melted,  and  caft  into  plated 
^bout  half  a  line  in  thicknefs,  four  or  five  inches  wide,  and  two 
feet  long.  Thefe  are  rolled  up  in  a  fpiral  form,  in  fuch  a  man- 
ner that  the  revolutions  remain  at  the  diftance  of  half  an  inch 
from  each  other.  They  are  then  placed  in  pots,  upon  three 
points,  which  proje6l  from  the  infide  at  about  one  third  of  the 
height.  Malt  vinegar  i^  poured  into  thefe  ix)ts  to  the  height  ojT 
the  bottom  of  the  lead,  and  they  are  buried  in  dung  beneatb 
iheds.  A  great  number  of  thefe  are  difpofed  befide  each  other^ 
and  feveral  ftrata  are  formed.  Care  is  taken  to  cover  each  pot 
with  a  plate  of  lead  and  boards*  At  tlie  expiration  of  a  month- 
ox  fix  weeks  they  are  taken  out,  and  the  white  lead  is  feparated. 
This  white  calx  is  then  ground  in  mills,  and  afterwards  put  in- 
to a  x'-at,  from  which  it  is  taken  out  to  dry*  The  drying  is  per- 
formed in  the  iliade,  becaufe  the  fun  impairs  the  colour.  For 
this  purpofe  it  is  put  into  fmall  conical  earthen  pots  ;  and  when 
fufficiently  dry  it  is  wrapped  in  paper,  a-nd  diflributed  for  fale. 

Cerufe  does  not  differ  from-  white  lead,  excepting  that  a  more- 
or  lefs  confiderable  quantity  of  chalk  is  mixed  with  it. 

All  the  oxides  of  lead  are  foluble  in  vinegar.  The  fblution 
of  the  acetate  of  lead,  duly  concentrated,  cryftalHzes  in  efHor- 
efcent  tetrahedral  prifms  ;  and  fo^ms  the  fait  of  faturn,  or  fugar 
of  lead. 

Cauftick  alkalis  dlfTolve  the  oxides  of  lead,  and  the  metal  ma^ 
be  precipitated  by  the  addition  of  acids.  When  the  alkaline 
fblution  is  concentrated,  the  lead  re-appears  nearly  in  the  me* 
tallick  form,  and  the  alkali  is  found  to  have  acquired  a  faint  and. 
very  peculiar  talle. 

*  I  do  not  hear  that  foda  ha*?  been  feparated  from  common  fait  by  * 
method  fufficiently  cheap  for  the  purpoies  of  commerce.  It  is  iwirver- 
fally  underftood  that  Mr,  Turner's  profits  arife  from  the  fale  of  the  com- 
bination of  muriatick  acid  with  the  lead,  which  forms  the  yellow  pigment 
known  in  London  by  the  name  of  Patent  Yellow.  It  may  be  produced 
fimply  by  the  fvifion  of  litharge  and  common  fait ;  the  alkali  beinjjTula- 
tilized,  and  driven  off,  if  tis  fire  te  fufficiently  inteoie,     T. 


XJJei  of  Leadi  ^c.  31^ 

Tlie  «fc«-©f  lead  in  the  arts  are  multifarious.  It  is  ufed  to 
OTake  water  pipes,  boilers,  coverings  for  the  roofs  of  buildings, 
rtea-chells  and  other  articles  of  package.  It  is  rendered  proper 
•for  t\\£(t  ufes,  either  by  laminating  it,  or  by  caufing  it  to  flow- 
out  upon  a  bed  of  fand  well  rammed  and  levelled,  or  upon  the 
eloth  called  ticking. 

It  is  likewife  ufed  to  make  bullets  and  fmall  fhot.  The  bul- 
lets are  caft  in  moulds  ;  but  the  fmall  fhot  is  made  in  the  fol- 
lowing manner  : — Lead  is  fufed  with  a  fmall  quantity  of  arfen- 
ick,  to  render  it  more  brittle ;  and  when  its  temperature  is  fuch 
©s  to  admit  of  a  card  being  plunged  in  it  without  burning,  it  is 
|)0ured  into  a  kind  of  cullender,  pierced  at  the  bottom  with  ma- 
lay  hok^  and  containing  lighted  chareoa-Uj  this  cullender  is 
held  over  watery  and  the  lead  afl^umes  a  round  form  as  it 
enters  this  liquid. 

Lead  is  ufed  in  the,  tinning  of  copper  veflels.  This  is  a  per- 
nicious fraud  fupported  by  cudom,  and  tolerated  by  the  want  of 
■vigilance  in  the  police.  It  is  the  more  dangerous  from  the  cir- 
•cumftance  that  fats,  oils,  and  vinegar,  corrode  or  dlllblve  lead, 
which  by  that  means  becomes  mixed  with  the  aliments. 

Lead  ore  is  likewife  ufed  to  glaze  pottery,  l^br  this  purpafe 
galena  is  pulverifed,  and  mixed  with  water.  The  veilel  intend- 
ed to  be  glazed  is  dipped  into  this  AukI,  after  having  been  ex- 
pofed  to  a  firft  baking.  It  accordingly  becomes  covered  with 
the  galena ;  which,  when  expofed  to  a  violent  heat,  pafles  to 
the  ftate  of  glafs,  and  forms  a  covering  of  the  glafs  of  lead 
over  the  whole  furface.  This  procefs  is  attended  with  the  in- 
convenience of  introducing  a  dangerous  poifon  into  our  culina- 
ry vcflels  whofe  efib£l:s  on  the  health  of  individuals  cannot  but 
be  fenfibly  felt. 

Oxided  lead  enters  into  the  ccmpolition  of  gJaffes,  cryftals, 
>and  enamels.  It  poflefTes  the  advantage  of  facilitating  the  fu- 
iion,  and  giving  the  glafs  an  undlous  feel,  and  a  degree  of  foft- 
nefs,   v/hich  renders  it  capable  of  being  cut  and  poliftied. 

White  lead  and  cerufe  are  ufed  by  painters.  Thefe  oxides 
pcfiefs  the  finguiar  advantage  of  not  being  perceptibly  altered 
by  their  mixture  with  oil ;  and  form,  by  their  whitenefs  and  bo- 
^y,  a  bails  or  receiver  which  is  very  fuitable  for  a  variety  of  col- 
ours. The  workmen  who  grind  thefe  colours  are  afFe<5led  by 
them ;  and  fooner  or  later  become  fubjeft  to  the  painters  colicky 
colic  ft  pi  Ei  ovum. 

Litharge  is  at  prefent  ufed  to  dccompofe  fea  fait  ;  and  the 
wuriate  of  lead  by  fufion  forms  a  fuperb  yellow,  very  much  em- 
ployed in  varnifli  colours. 


3*4  CharaHers  of  Tin, 

8.  Cerufe  is  like  wife  much  ufed  for  drying  up  habitual  moif- 
turc  of  the  ikin,  and  for  flight  burns.  It  is  applied  to  the  Ikitt 
in  the  form  of  powder,  and  there  is  no  remedy  more  fpeedy. 

The  fait  of  faturn,  or  fugar  of  lead,  is  almoft  entirely  ufed  by 
the  caiiico  printers. 

The  vinegar  of  faturn,  or  the  vegeto-mineral  water  of  Mr. 
.  Goulard,  is  a  very  proper  aftringent  in  the  confequences  or  re« 
.  mams    of    venereal  diforders  :  it  is  likewife  ufed  to  waih  burns 
and  ulcers,  and  to  facilitate  their  cure. 

This  extra£l  is  likewife  ufed  to  clarify  liquors,  and  to  deprive 
brandies  of  their  colour  •,  an  evil  pra£tice  which  has  been  com- 
mon for  fome  years  at  Sette,  though  prohibited  under  heavy 
penalties.— The  wine  merchants  avail  themfelves  of  this  com- 
pofition  but  too  often,  or  of  litharge,  to  render  their  four  wines 
fWeet.  This  fraud  was  prodigioufly  common  at  Paris  in  tie 
year  1750;  and  it  was  proved  that,  in  the  interval  of  three 
years,  thirty  thoufand  muids  ofi-H'inegar  had  been  thus  fweeten- 
cd,  and  fold  for  wine. 

The  oxides  of  lead  are  likewife  ufed  to  harden  oils,  or  to  ren- 
der them  more  drying.  In  this  operation  the  oxigene  of  the 
oxide  combines  with  the  oil,  and  caufes  it  to  approach  nearer 
to  the  nature  of  refms.  There  is  likewife  a  folution  of  lead  iii 
oils,  which  ferves  as  the  bafis  of  plafters- 


CHAPTER    IX. 
Concerning  Tifl. 

TIN  is  a  metal  of  a  white  colour,  intermediate  between  that 
of  lead  and  filver.  It  is  very  flexible,  and  produces  a  crackling 
noife  when  bended.  No  other  metal  poiTefles  this  property  ex- 
cept zinc,  in  which  it  is  infinitely  lefs  marked. 

This  metal  is  very  foft,  and  the  lighteft  of  any  of  the  entire 
metals.  The  fpecifick  gravity  of  fufed  tin  is  7.2914,  accordiHg 
to  Briflbn.  ^ 

A  cubick  foot  of  this  metal  weighs  about  five  hundred  aivd 
ten  pounds.  It  is  very  ductile  under  the  hammer  ;  and  its  te- 
nacity is  fuch,  that  a  wire  one  tenth  of  an  inch  in  diameter  is 
capable  of  fuppoiting  forty-nine  pounds  eight  ounces  without 
breaking.  Mr.  De  la  Chenaye  has  cryftallized  tin  after  feveral 
.repeated  fufions  ;  he  obtained  by  this  means  an  alTemblage  o€ 
prifms  united  together  Cdeways. 


Ores  cf  Tin.  ,  325 

f  Tin  has  been  found  in  the  metallick  ftate  in  the  bowels  of  the 
earth,  Mr.  Sage  pofTefles  a  fpccimen  from  the  mines  in  Corn- 
wall, and  Mr.  De  Lifle  likewii'e  has  one  in  his  colledHon.  This 
tin  fo  far  from  exhibiting  any  trace  of  fiifion,  has  the  external 
appearance  of  molybdena  :  it  is  eafily  broken  ;  but  the  detached 
pieces  may  be  flattened  by  the  hammer. 

Tin  ore  is  either  white  or  coloured.  ' 

I.  The  white  tin  ore,  which  has  been  often  confounded  with 
lungften,  cryftallizes  in  oftahedrons.  Its  texture  is  lamellated> 
and  it  frequently  includes  portions  of  reddiih  tin  ore.  That  of 
Cornwall  afforded  Mr.  Sage  iixty-four  pounds  of  tin  in  the  quin- 
tal. 

.  2.  The  coloured  tin  ore,  does  not  differ  from  the  preceding, 
excepting  that  it  contains  iron,  and  fometimes  cobalt.  This  ore 
ufually  has  the  form  of  irregular  polyhedrons. 

Thefe  ores  afl^brd  carbonick  acid  by  diflillation  when  expofed 
to  fire  in  a  crucible.  They  decrepitate,  lofe  fomewhat  of  their 
colour,  and  become  one  tenth  lefs  heavy. 

Bergmann  found  fulphurcous  tin  among  the  minerals  he  re- 
ceived from  Siberia.  He  afhrms  that  this  was  of  a  golden  col- 
our externally,  refembling  aurum  mufivum  ;  and  internally  it 
prefented  a  mafs  of  radiated,  white,  brilliant,  brittle  cryflals, 
which  affumed  changeable  colours  on  expofure  to  the  air. 

To  affay  a  tin  ore  nothing  more  is  neceflary  than  to  fufe  it  in 
the  midfl  of  the  coals.  Calcination  in  the  open  fire  diflipates 
much  of  the  metal,  according  to  the  obfervation  of  Cramer. 

In  the  working  of  tin  ores,  the  mineral  muft  be  forted  very  f  x- 
a£l:ly  ;  after  which  it  is  to  be  pulverized,  and  wafhed  upon  tables 
covered  with  cloth.  By  agitation  with  a  wifp  or  broom,  the  gan- 
gue  is  fufpended  or  carried  away  by  the  water,  and  the  tin  ore 
remains  alone. 

The  furnace  made  ufe  of  in  Saxony  for  the  fufion  of  tin  ore,_ 
is  a  variety  of  the  blaft  furnace,  on  the  hearth  of  which  is  a 
groove  to  receive  the  melted  metal,  and  convey  it  into  a  bafoh  j 
whence  it  is  taken  to  be  caft  in  moulds  of  copper  or  of  iron. 

The  tin  ores  of  Cornwall  are  frequently  mixed  with  copper, 
and  arfenical  pyrites.  The  quartz,  which  is  its  gangue  is  very 
hard ;  and  on  this  account  the  operation  is  begun  by  torrefac- 
tion  of  the  ore  before  it  is  pulverized.  After  the  ore  is  wafhed, 
a  feparation  of  the  magnetical  iron  is  efFeded  by  means  of  load- 
llones.     The  ore  is  ufually  fufed  in  the  reverberatory  furnace. 

In  Saxony,  and  in  England,  the  fcorise  are  three  times  fufed 
to  feparate  the  tin,  after  which  they  are  pounded  to  feparate  the 
lafl  portions  of  metal.  As  the  vein  of  tin  in  the  mines  of  Corn- 
vall  is  always  mixed  or  accompanied  with  a  vein  of  copper,  the 


%-24  Puffy  and  tht  OxiJes  of  fin. 

tin  muft  contain  this  latter  metal,  however  great  the  precautioa* 
which  may  be  attended  to  in  the  working. 

We  are  acquainted  with  three  kinds  of  tin  in  commerce. 

I.  Pure  tin,  fuch  as  that  of  Malacca,  of  Banca,  and  the  {&k 
tin  of  Eni^land.  The  tin  of  Malacca  is  call  into  mouWs  which 
give  it  the  form  of  a  quadrangular  truncated  pyramid!,  with  a 
Imall  rim,  at  its  bafe.  It  is  calie^i,  in  France,  litam  en  Chapcau^ 
or  m  Eeriioire.  Each  ingot  weighs  one  poujid.  The  tin  oi 
Banea  is  in  the  form  of  oblong  ingots,  weighing  from  imx^  to 
forty-five  pountis  each. 

2*  The  Englifli  tin,  in  large  pigs,  is  .<:aft  into  flicks  di  t€li  or 
twelve  lines  in  diameter,  and  a  foot  and  a  half  long. 

3.  The  tin  of  the  pewterers  is  alloyed  with  various  metals. 
*rhe  law  in  France  permits  them  to  add  coppjer  and  bifmmh  \ 
and  they  of  their  own  authority  add  zinc,  lead,  and  antimony. 

Every  kind  of  tin  enters  into  fufion  with  conliderable  facility, 
JFor  it  is  the  moft  fufible  of  the  metals.  If  it  be  kept  in  fufion 
for  a  fhort  time,  expofed  to  the  a£lion  of  the  air,  the  fu-rface  be* 
comes  wrinkled,  and  covered  with  a  grey  pellicle.  If  this  iirft 
covering  be  taken  oif,  the  tin  appears  with  all  its britliancy  5  btit 
foon  becomes  dull,  and  is  oxided  again.  Tin  gains  one  tenth  oC 
its  weight  by  this  calcination.  When  the  oxide  is  white  it  is 
then  called  Putty.  It  is  this  oxide  of  tin  which  th€  makers  of 
pewter  fpoons  who  ufually  travel  over  the  country,  call  the  Drofs 
of  Tin.  They  are  very  careful  to  fcum  the  metal  as  often  as 
pcfiibie,  to  clear  it  of  the  drofs  5  and  by  this  means  they  avoid 
giving  the  peafant  any  more  of  his  old  pewter  than  that  vrhich 
they  cannot  contrive  to  take  away  from  him.  They  are  very 
v/eii  acquainted  with  the  art  of  fufing  this  pretended  drofs  into 
good  til),    by  heating  it  in  contact  with  charcoal. 

The  putty  of  tin  is  ufed  to  poliOi  hard  bodies  :  and  to  render 
l>hfb  opaque,  which  converts  it  into  enamel.  Tin  takes  lire  by 
a  violent  heat,  according  to  Geoffroy  ;  and  a  white  oxide  fub- 
limes,  while  part  of  the  tin  is  converted  into  a  ghfs  of  a  hyacin- 
thine  colour. 

If  tin  be  kept  in  fufion  in  a  lined  crucible,  and  the  furface  be 
covered  with  a  quantity  of  charcoal  to  prevent  its  calcination, 
the  metal  becomes  whiter,  more  fonorous,  and  harder,  provided 
the  fire  be  kept  up  for  eight  or  ten  hours. 

Tin,  and  fcveial  other  metals,  may  acquire  a  brilliancy  they 
do  not  ufually  poflefs,  by  pouring  them  out  at  the  moment  be^ 
fore  they  would  congeal  in  the  crucible.  This  treatment  fe- 
cures  them  from  the  oxidation  they  fufl^er  in  cooling,  whea" 
they  are  poured  out  too  hot ;  and  by  this  method,  which  is 
very  fimple,  I  have  procured  to  tin  and  lead  a  degree  of  brilltan«. 
cy  which  they  would  liardly  be  thought  capable  of  exhibiting. 


Fuming  Liquar  fff  Li&svfuf,  giy 

Tin,  diftilletl  in  clofe  veilels,  affords  a  white  fubllmate  in  the 
abeck  of  the  retort,  which  MargrafF  took  for  arfenick ;  but 
Meflrs.  Bayen  and  Chariard  have  proved  that  it  was  not  tha5 
fiibrtance. 

The  a<5\ion  of  acids  upon  tin  varies  according  to  tlie  degree 
of  pur  ft  y  of  the  metal. 

The  fulphurick  acid  of  commerce  ditTolves  tin,  by  the  aflifl- 
ance  of  heat ;  but  part  of  the  acid  is  decotnpofed,  and  fli^s  o^ 
in  the  form  of  very  penetrating  fulphureous  acid.  Water  alone 
precipitates  this  oxided  metal.  Mr.  Monnet  has  obtained  cryf- 
tals  by  calcination,  which  refemble  fine  needles,  interlaced  a- 
mong  each  other.  The  fulphurick  acid  diflblves  the  oxide  of 
tin  much  better. 

The  nitrick  acid  devours  tin.  The  decompofition  of  this  fol- 
v^nt  is  fo  fpeedy,  that  the  metal  is  {ctn  to  be  precipitated,  al- 
mod  inftantly,  in  a  white  oxide.  If  this  zcid  be  loaded  with  all 
the  tin  it  is  capable  of  calcining,  and  the  oxide  be  wa(hed  with 
a  confiderable  quantity  of  diiUlied  water,  a  fait  may  be  obtainedi 
by  evaporation,  which  detonates  alone  in  a  crucible  well  heated, 
^nd  which  burns  with  a  white  and  thick  flame,  like  that  of  a 
phofphorus.  The  nitrate  of  tin,  diftillcd  in  a  retort,  fwells  up, 
boils,  and  fills  the  receiver  with  a  white  and  thick  vapour,  which 
has  the  fmell  of  nitrick  acid. 

Mr.  Baume  even  pretends  that  the  nitrick  acid  doss  not  dif- 
folve  tin  ;  but  Kunckel,  and  the  famous  Rouelle,  have  main- 
tained the  contrary.  Meffrs.  Bayen  and  Charlard  diiToIved  five 
grains  in  two  gros  of  pure  nitrick  acid,  dikitqd  with  four  gro» 
of  diftilled  w^ter. 

The  muriatick  acid  difiblves  tin,  w!iethcr  cold  or  heated. 
During  the  efFervefcence,  a  very  fetid  gas  is  difengaged. 

The  folution  is  yellowifli,  and  affords  needle-formed  cryilalvV 
by  evaporation,  which  attracts  the  humidity  of  rhe  air,  Mr. 
Baume  prepared  this  fah  in  a  large  way  fot  the  callico  printers. 
Gitt  of  twelve  pounds  of  tin,  diflblved  in  forty-eight  pounds  of 
acid,  he  had  a  refidue  of  two  ounces  fix  gros  of  a  grey  and  folu- 
ble  powder,  which  Margrafflud  taken  for  arfenick'.  Mr.  Bau- 
me has  obferved  that  the  cryftals  of  the  muriate  of  tin  differ  ac- 
cording to  the  ftate  of  the  acid.  He  obtained  cryftals  fimilar 
to  thole  of  the  fulphate  of  foda,  in  needles,  or  in  fcale.s  like  thofe 
of  the  acid  of  borax.  Mr.  Monnet  all'crts  that  he  obtained,  bv 
the  diftillation  of  a  muriate  of  tin,  a  fat  matter,  a  true  butter  of 
tin,  and  a  liquor  refembling  that  of  Libavius. 

The  oxigenated  muriatick  acid  difiblves  tin  fpeedily  ;  and  the 
ialt  which  it  produces,  pofTefles  all  the  charaftersof  the  ordina- 
ry muriate,  according  to  Mr  Dc  Fo\ircroy, 


M 


328  Scarlet  Compojition, 

That  wliich  is  known  by  the  name  of  the  Fuming  Liquor  of 
Libavius,  appears  to  me  to  be  a  muriate  of  tin,  in  which  the  acid 
is  in  the  ftate  of  the  oxigenated  muriatick  acid.  To  make  this 
preparation,  tin  is  amalgamated  with  one  fifth  of  mercury  ;  and 
this  amalgam  in  powder  is  mixed  with  an  equal  weight  of  cor- 
rofive  fublimate.  The  whole  is  then  introduced  into  a  retort,  a 
receiver  adapted,  and  diftillation  proceeded  upon  by  a  gentle  heat, 
Aninfipid  liquor  pafles  over  firft,  which  is  followed  by  a  fudden 
eruption  of  white  vapours,  which  condenfe  into  a  tranfparent 
liquor,  that  emits  a  confiderable  quantity  of  vapours,  by  mere 
cxpofure  to  the  air.  The  refidue  in  the  retort,  for  an  analyfis 
of  which  we  are  indebted  to  Mr  Rouelle  the  younger,  confifts 
of  a  flight  lining  in  the  neck  of  the  retort,  which  contains  a 
fmall  quantity  of  the  fuming  liquor,  feme  muriate  of  tin,  muri- 
ate of  mercury,  and  running  mercury.  The  bottom  of  the  vef- 
fel  contains  an  amalgam  of  tin  and  mercury  ;  above  which  lies 
a  muriate  of  tin  of  a  grey  white,  folid  and  compadl,  and  which 
maybe  volatilized  by  a  ftrong  heat. 

The  nitro- muriatick  acid  diilblves  tin  with  vehemence  :  a  vi- 
olent heat  is  excited  ;  and  it  frequently  happens  that  a  magma? 
is  obtained  refembling  pitch,  which  becomes  harder  in  the  pro- 
cefs  of  time.  This  happens  when  the  very  concentrated  acid 
has  diflblved  too  much  of  the  metal  ;  and  thefe  inconveniences 
may  be  obviated  by  adding  water  in  proportion  as  the  fol^tio:i 
proceeds. 

The  folution  of  tin  which  conftitutes  the  compofition  for 
fcarlet,  is  made  with  the  common  aqua-fortis,  prepared  with 
i^iltpetre  of  the  firft  boiling.  This  is  a  kind  of  nitro-muriatick 
acid,  which  unfortunately  varies  in  its  properties,  according  to 
the  two  variable  proportions  of  muriate  of  foda  and  nitrate  of 
pot-afii.  For  this  reafon,  the  dyers  are  continually  making 
complaints,  either  that  the  aqua-fortis  precipitates,  which  hap- 
pens when  it  contains  too  fmall  a  quantity  of  muriatick  acid  ; 
or  that  it  affords  an  obfcure  colour,  which  depends  on  an  excefs 
of  the  fame  acid.  The  firft  inconvenience  is  remedied  by  dif- 
folving  fea  fait,  or  fal  ammoniack,  in  the  aqua-fortis  5  and  the 
fecond  by  adding  faltpetre. 

The  moft  accurate  proportions  to  make  a  good  folventfor  tin, 
are,  two  parts  of  nitrick  acid,  and  one  of  muriatick  acid. 

Tin  is  likewifc  foluble  in  the  vegetable  acids.  Mr.  Schultz, 
in  his  difPertation  De  Morte  in  Olla^  has  demonftrated  the  folu- 
bility  of  this  metal  in  acids.  Vinegar  corrodes  it  by  a  gentle 
heat,  according  to  the  experiments  of  MargrafF. 

Moft  of  the  tin  in  commerce  is  alloyed  with  various  metals. 
That  of  England  contains  copper  and  arfenick  artificially,  ac- 


Alleys  of   Tin.  329 

orciing  to  GeOiTfcy  ;    and  naturally,  according  to  the  Baron 
bietrich.  Sage,  &c.       The  tin   of  the    plumbers  or  pewterers, 
ailed  Pewter,   contains  feveral  metals.       The   ordonnance    in 
ranee  permirs  them  to  add  a  fmall  quantity  of  copper  and  Bif- 
'muth.     The  firO:  metal  renders  it  hard  ;  and  the  latter  reftores 
e  brightnefs  which  would  elfe  have  been  impaired  by  the  cop- 
er, and  renders  it  more  fonorous.      The  pewterers  take   upon 
hemfelvcs  to  add  antimony,  zinc  and  lead  ;     the  antimony  har- 
ens  it,  the  zinc  renders   it  whiter,   and  the  lead  diminifhes  its 
value.    It  is  a  defirable  circumftance  to  pofTcfs  the  means  of  af- 
certaining  the  nature  and  proportions  of  thefe  alloys.       We  are 
indebted  for  the  following  procefTis  to  MelTrs.  Bayen  and  Char- 
lard. 

A.  When  tin  contains  arfenick,  the  folution  in  the  muriatick 
acid  exhibits  a  black  powder,  which  confifls  of  arfenick  feparated 
from  the  tin.  This  method  is  capable  of  rendering  the  two 
thoufand  and  forty-fecond  part  of  alloy  perceptible. 

B.  If  the  tin  contains  copper,  the  muriatick  acid^  which  at- 
tacks tin  with  facility,  precipitates  the  copper  in  the  form  of  a 
gjrey  powder,  provided  there  be  no  accefs  of  acid,  and  the  fo- 
lution be  made  without  heat.  The  copper  is  likewife  precipi- 
tated by  a  plate  of  tin  immerfed  in  the  folution. 

C.  Bifmuth  is  fliewn  by  the  fame  procefs  as  the  copper. 

D.  Toafcertain  the  mixture  of  lead,  the  nitride  acid  muft  be 
ufed,  which  corrodes  the  tin,  and  diilblves  the  lead. 

The  pewterers  have  two  methods  of  afTaying  this  metal. 

I.  The  ailay  of  the  (tone,  which  confifts  in  pouring  it  into  a 
hemifpherical  cavity  made  in  a  calcareous  (tone,  and  terminating 
in  a  channel  or  groove.  The  workman  attentively  obferves  the 
phenomena  of  its  cooling  \  and  from  thefe  circumftances,  as 
well  as  from  the  crackling  or  noife  which  the  tail  of  the  afTay 
affords  when  bended,  he  judges  of  the  purity  of  the  metal. 

2.  The  alTay  by  the  ball  confifts  merely  in  a  comparifon  of 
the  weight  of  pure  tin  with  that  of  adulterated  or  alloyed  tin> 
poured  into  the  fame  mould. 

It  cannot  but  be  immediately  perceived  that  thefe  methods 
are  very  imperfccfl. 

The  various  metals  which  are  prejudicial  to  health,  are  not 
added  to  the  tin  in  a  fuHiciently  great  proportion  to  produce  any 
dangerous  efic61s.  It  feems  that  MargraiF  was  deceived  by  foms 
foreign  circumftance,  when  he  afhrmed  that  the  tin  of  Morlaix 
contains  thirty-fix  grains  of  arfenick  in  the  half  ciince  ;  for  this 
quajitlty  is  more  than  uuTicient  to  render  the  metal  as  brittle  as 
zinc.  Meffi-s.  l>ayen  and  Charlard  found  no  arfenick  in  the  tin 
<>f  Banca  and  of  Malacca.  The  tin  of  Etieland  never  contains 
2...S  ^ 


330  Aurum  Mufivum. 

more  than  three  fourths  of  a  grain  of  arfenick  in  the  ounce  of 
metal ;  and  fuppofing  this  to  be  the  maximum,  the  daily  ufe  of 
tin  cannot  be  dangerous  ;  fince  a  plate  in  which  arfenick  exifted 
in  this  proportion,  loft  no  more  than  three  grains  per  month  by 
conftant  ufe,  which  amounts  to  the  five  thoufand  feven  hundred 
and  fixtieth  part  of  a  grain  of  arfenick  loft  daily.  The  experi- 
ments which  thefe  two  Ikilful  chemifts  have  made  upon  animals, 
by  mixing  arfenick  in  larger  proportions  with  tin,  are  fuflicient 
to  remove  every  apprehenfion  concerning  the  ufe  of  this  metal. 

The  lead  alone  may  be  productive  of  dangerous  confequences,. 
becaufe  the  pewterers  add  it  in  a  very  confiderable  proportion. 

The  combination  of  tin  with  fulphur  forms  aurum  mufivum, 
or  mofaick  gold.  The  procefs  for  making  it  which  has  beft  fuc- 
eeeded  in  my  hands,  is  that  defcribed  by  the*  Marquis  de  Bul- 
lion. It  confifts  In  forming  an  amalgam  of  eight  ounces  of  tin 
and  eight  ounces  of  mercury.  For  this  purpofe,  a  copper  mor- 
tar is  heated,  and  mercury  poured  into  it  :  and  when  it  has  ac- 
quired a  certain  degree  of  heat,  the  melted  tin  is  poured  in,  and 
the  mixture  agitated  and  triturated  till  cold.  Six  ounces  of  ful- 
phur, and  four  ounces  of  fal  ammoniack,  are  then  mixed  ;  and 
the  whole  put  into  a  mattrafs,  which  is  to  be  placed  on  a  fand 
bath,  and  heated  to  fuch  a  degree  as  to  caufe  a  faint  ignitioo  in 
the  bottom  of  the  mattrafs.  The  fire  muft  be  kept  up  for  three 
hours.  The  aurum  mufivum  thus  obtained  is  ufuaily  beauti- 
ful :  but  if,  inftead  of  placing  the  mattrafs  on  the  fand,  it  be 
immediately  expofed  upon  the  coals,  and  ftrongly  and  fuddenly 
heated,  the  mixture  will  take  fire,  and  a  fublimate  will  be  form- 
ed in  the  neck  of  the  veffel,  which  confifts  of  the  moft  beautiful 
aurum  mufivum.  I  have  obtained  it  by  this  procefs  of  a  daz- 
zling colour  in  large  hexagonal  fcales. 

The  mercury  and  the  fal  ammoniack  are  not  in  ftriflnefs 
neceirary  to  the  produflion  of  aurum  mufivum.  Eight  ounces 
of  tin  diflblved  in  the  muriatick  acid,  precipitated  by  the  carbo- 
nate of  foda,  and  mixed  with  four  ounces  of  fnlphur,  produced 
the  Marquis  of  Bullion  a  fine  aurum  mufivum  :  but  this  is  not 
capable  of  increafmg  the  ellecls  of  the  ele£lrical  machine,  which 
proves  that  the  compofition  owes  its  virtue  in  that  refpedl  to 
the  mercury  it  contains  in  the  proportion  of  fix  to  one,  when 
prepared  in  the  former  procefs.  This  preparation  is  ufed  to 
give  a  beautiful  colour  to  bronze,  and  to  increafe  the  effeQs  of 
the  eleftrical  machine  by  rubbing  the  cufhions. 

The  Baron  Kienmayerhas  defcribed  the  following  amalgam, 
compofed  of  two  parts  of  mercury,  one  of  zinc,  and  one  of  tin. 
—The  zinc  and  the  tin  are  to  be  fufed,  and  mixed  together 
w  ith  the  mercury  5  and  the  mixture  agitated  in  a  wooden  box, 


Silveritigof  GlaJJes,     Iron.  3^,1 

internally  rubbed  with  chalk.  The  mafs  is  then  to  be  reduced 
to  a  fine  powder  -,  and  employed  in  that  itate,  or  mixed  with 
greafe.  The  efFe£l  of  this  amalgam  is  furprifing  ;  for  by  this 
means  the  power  of  eledtrical  machines  is  inconceivably  aug- 
mented. 

The  amalgam  of  tin  is  capable  ofcryllallization.  Mr.  Sage's 
jjrocefs  confiits  in  pouring  two  ounces  of  melted  tin  into  a 
pound  of  mercury.  After  having  introduced  this  mixture  into 
a  retort,  he  urged  it  by  a  violent  fire  for  five  hours  on  the  fand 
bath.  No  mercury  was  difengaged  ;  but  the  tin  was  found  in 
a  cryftallized  ftate  above  the  mercury  v/hich  had  not  entered  in- 
to combination.  The  lower  part  of  this  amalgam  is  compofed 
of  grey  brilliant  cryftals  in  fquare  plates, thin  towards  their  edges, 
having  polygonal  cavities  between  each.  Every  ounce  of  tin 
retains  in  its  cryftallization  three  ounces  of  mercury. 

The  amalgam  of  tin  is  ufed  to  filver  looking-glafies.  For 
this  purpofe,  a  leaf  of  tin  is  fpread  out  upon  a  table  of  the  fize 
of  the  glafsj  mercury  is  poured  upon  it,  and  fpread  about  with  a 
brufli.  This  being  done,  a  larger  quantity  of  mercury  is  pour- 
ed upon  the  tin,  fo  as  to  form  a  covering  of  more  than  one  hne 
in  thicknefs.  The  glafs  is  Hided  upon  this  covering,  by  prefent- 
ing  one  of  its  edges  ;  taking  care  at  the  fame  time  that  its  fur- 
face  Ihail  be  beneath  the  level  of  the  mercury,  in  order  that  the 
impurities  which  might  hinder  a  perfect  contadl  may  be  driven 
before  it.  The  plate  of  glafs  is  then  loaded  with  weights  equal- 
ly dillributed  over  its  whole  furface  ;  by  which  means  ail  the 
cxcefs  of  mercury  is  prefled  out,  and  flows  away  through  chan- 
nels made  in  the  edges  of  the  table.  The  air  being  driven  out 
from  between  the  amalgam  of  tin  and  the  glafs  by  this  ftrong 
compreflion,  ferves  greatly  to  render  the  amalgam  adherent. 
Several  days  are  required  to  elapfe  before  it  be  fufficiently  dry 
to  admit  of  removing  the  glafs. 

Tin  alloyed  with  copper  forms  bronze,  or  bell-metal.  Seven 
parts  of  bifmuth,  five  of  lead,  and  three  of  tin,  form  an  alloy 
which  Jiquefies  in  boiling  water. 


CHAPTER     X. 

Concerning  Iron, 

IRON  is  the  mod  generally  diffufed  metal  in  nature.  Ai- 
moit  every  mineral  fubftance  of  this  globe  is  coloured  with  it  ; 
and  its  various  alterations  produce  that  truly  altonilhing  variety 
of  colours  which  are  comprehended  between  the  blue  and   the 


332  Nciilve  Iron^ 

deepeft  red.  This  metal  likewife  exifis  in  the  vegetable  king-r 
dom,  where  it  conftitutes  an  ahxioft  infeparable  principle.  It 
even  appears  to  be  one  of  the  producls  of  organization,  or  veg- 
etation ;  for  ic  is  found  in  vegetables  which  are  fupported  mere- 
ly by  air  or  v/ater.  It  is  indeed  tontrary  to  found  philofophy 
to  fappofe  that  all  the  iron  with  which  earths  are  impregnated, 
muft  arife  from  the  wearing  of  ploughlliares  :  for,  not  to  men- 
tion that  the  plough  has  not  paffed  every  where,  we  fee  iron 
daily  formed  in  vegetables.  There  is  no  reafon  to  fear  that  the 
metal  fnould  on  this  account  become  too  abundant  ;  becaufe  it 
is  continually  deftroyed  by  palling  to  the  itate  of  oxide. 

If,  on  the  other  hand,  we  call  our  attention  towards  the  infi- 
nite number  of  ufes  to  which  this  metal  is  applied  in  fociety,  we 
iliail  perceive  that  it  is  perhaps  the  mofl:  effential  to  be  known, 
becaufe  it  is  the  mofl  diilufed,  the  moft  ufeful,  aiid  the  moit 
employed. 

This  metal  is  of  a  white  livid  colour,  inclining  to  grey,  obe-: 
dient  to  the  magnet,  and  gives  fire  with  quartz  ;  which  lad  cir- 
cumflance  is  attributed  to  the  fufion  and  rapid  combuftion  of 
particles  of  the  metal  detached  by  the  ftroke.  It  is  the  lightell 
yf  all  metals  except  tin.  One  cubick  foot  of  forged  iron 
weighs  five  hundred  and  forty-five  pounds.  The  fpecihck  grav- 
ity of  fufed  iron  is  7.207o.^See  Briffon. 

Iron  is  very  hard,  fufceptible  of  a  fine  poliQi,  and  very  difficult 
of  fufion.  It  may  be  drawn  into  very  fine  wire,  of  which  the 
Itrings  of  the  harpficard  are  made.  It  becomes  hard  by  ham- 
mering, without  heat  \  but  when  afhfted  by  heat,  it  may  be 
hammered  into  every  imaginable  form. 

Iron  is  univerfally  difperfed  ;  bur,  by  common  confent,  thofe 
places  or  matrices,  in  which  the  iron  is  fufliciently  abundant  to 
be  wrought  with  profit,  are  called  Iron  Mines,  or  Ores. 

Iron  is  found  native,  without  mixture,  in  fcveral  places. 
We  (hall  not  here  mention  thofe  ridiculous  aflbrtions,  which 
have  no  other  merit  than  that  of  having  been  authorized  by  the 
fuffrages  of  certain  celebrated  men. — *'  Albertqs  Magnus  de-. 
cidilfe  coelum,  imbre,  maflam  ferri  centum  librarum.  Peterman- 
nus  magna  tempcftate,  cum  projec^tu  multorum  lapidum,  coelo. 
mclem  ferri  decidille,  qux  in  longitudine  fexdecim,  m  latitudine 
quindeciin  in  crafiitie  duos,  pecies  liabuerit :"  that  is,  of  the 
weight  of  forty-eight  thoufand  pounds,  and  containing  four 
hundred  and  eighty  cubick  feet. — Becher,  fupplem.  in  Phyf. 
Subter.  cap.  iii.  p.  599. 

We  are  indebrcd  to  Lehmann  for  a  defcription  of  a  piece  of 
native  iron  poffefTed  by  Margraff,  which  ciime  from  EibenflocL 
in  Saxony.     The  grain  was  diftinguf (liable  on  both  ildes. 


Ores  crf  Iron,  233 

Henckel  poflefied  a  fmall  piece  incrufled  with  a  yellow  earth  j 
and  the  cabinet  of  the  Royal  School  of  irines  pcficiibs  one  which 
is  covered  with  fpathofe  iron  ore.  Adani'on  aiid  Vv'allerius 
affirm  that  it  is  found  in  Senegal  j  and  Rouelie  received  a  piece 
from  thence  which  was  very  malleable.  Simon  Pallas  fpeaks  of 
a  mafs  of  native  iron  found  near  the  great  river  Jeneiei  in  Sibe- 
ria. This  iron  is  very  fpongy,  very  pure,  perfectly  flexible, 
and  proper  to  be  formed  into  inttruments  by  a  moderate  fire. 
it  is  naturally  incruiled  with  a  kind  of  varnifh  which  preferves 
it  from  ruit. 

Mr  Macquart  doubts  the  legitimacy  of  the  native  iron,  de- 
fcribed  by  Pallas  :  he  thinks  that  it  may  be  confidered  as  fufed 
iron.  Mr.  De  Morveau  does  not  believe  in  the  exillence  of  na- 
tive iron. 

Though  fome  doubts  may  be  raifed  concerning  the  legitimacy 
cf  thefe  pieces,  and  there  may  be  reafons  to  coniider  fome  of 
them  as  confequences  of  the  action  of  fire,  we  cannot  however 
r-efufe  to  admit  of  the  exiftence  of  native  iron,  after  the  depofi- 
tions,  fa£f  s,  and  atteftations  which  prefent  themfelves  on  ail  fides 
in  fupport  of  this  truth. 

Iron,  fiowly  cooled,  cryftallizes  in  octahedrons  almoH:  always 
implanted  one  in  the  other.  We  are  indebted  to  Mr.  Grignori 
for  this  obfcrvation.  I  am  in  poireiTion  of  a  piece  of  iron  entire- 
ly covered  with  fmall  tctrahedrai  fiat,  and  truncated  pvramids. 
Some  of  the  pyramids  have  a  bafe  of  one  line  in  breadth.  If 
comes  from  the  frontiers  of  the  Comtc  de  Foix.  This  iron  is 
very  feldom  found  unaltered  by  foreign  admixtures  ;  but  I  think 
we  may  confider  all  'the  iron  ores  which  are  attratied  by  the 
magnet,  as  containing  the  native  metal,  difperfed  in  ibmc  gangue : 
and  we  ihali  attend  to  thefe  fpecies  before  we  treat  of  the  oxides 
and  martial  falts. 


ARTICLE      I. 

Coacerning  Iron  Ores  which  are  attni'fled  by  the  Magnet. 

I.  The  octahedral  iron  ore. — This  ore  has  the  form  of  o<fta- 
hedrons,  ifolated,  and  difperfed  in  a  gangue  of  fchifius,  or  cal- 
careous (lone.  *rhe  cryftals  are  grey,  very  regular  in  their  form 
and  ilrongly  bedded  in  ihe  If  one.  'iheir  fize  is  from  half  a  line 
to  fix  or  {t\ti\  in  diameter.     Corfica  and  Sweden  aiford  this  kind. 

Mr.  Sage  obferves  that  0(flahedral  cryftals  of  iron  are  fome- 
times  found  in  the  iinelt  white  marble  of  Carara.  The  black 
furruginous  fand  which  accompanies  the  hyacinths  in  the  brook 
oi'  £;::pailly,  is  an  octahedral  iron  ore,  obedient  to  the  magnet, 


334  ^''^^  Ores.     The  MagneU 

2»  Iron  ore  in  fmall  plates  or  fcales. — The  fmall  plates  or 
fcales  which  are  attracted  by  the  magnet,  and  are  found  in  molt 
rivers  which  contain  gold,  are  an  iron, ore,  nearly  in  the  metal- 
lick  ftate.  This  fand  forms  the  relidue  which  is  left  after  the 
precious  metal  has  been  taken  up  by  amalgamation.  It  is  mix- 
ed with  fragments  of  quartz,  garnets,  &c.  1  have  found  a  large 
quantity  in  the  fand  of  the  river  Ceze  :  it  was  alfo  fent  me  from 
the  neighbourhood  of  Nantz.  I  have  received  fome  likewife 
from  Spain  j  and  this  fand  has  afforded  me  certain  phenomena 
which  appear  to  entitle  it  to  a  particular  rank  among  the  metals. 
Acids  diflblve  it  by  the  aihftance  of  heat  ;  and  always  without 
eifervefence,  or  the  difengagement  of  gas.  It  communicates 
the  fame  colour  to  the  nitro-muriatick  acid  as  platina  does.  It 
is  indecompofable  by  heat,  either  in  the  open  fire,  or  in  open 
veflels.  I  have  endeavoured  to  reduce  it  by  ail  the  known  flux- 
es, but  in  vain.  It  precipitates  in  the  flux,  mixes  with  it,  and 
recovers  its  form  and  magnetick  virtue  by  pulverizing  the  mafs. 
It  pollefles  feveral  characters  of  the  fiderotete,  or  phofphate  of 
iron. 

3.  Iron  difperfed  in  {tones  renders  them  obedient  to  the  mag- 
net. The  ophites,  the  ferpentines,  the  micas,  the  pot-ftones, 
and  feveral  marbles,  are  in  this  fituation.  Iron  diffeminated  in 
a  gangue  of  quartz,  or  very  hard  jafper,  forms  emery,  which 
on  account  of  its  hardnefs  is  ufed  to  grind  and  polifh  glafs.  It 
comes  to  us  from  Jerfey  and  Guernfey,  where  it  is  plentifully 
found. 

The  magnet  itfelf  is  nothing  elfe  but  the  iron  we  fpeak  of, 
modified  in  fuch  a  manner  as  to  afford  a  paffage  to  the  magnet- 
ick fluid,  and  to  exhibit  the  known  phenomena.  The  magnet 
is  fometimes  found  in  a  regular  form.  Mr.  Sage  affirms  that 
he  poffefles  a  fmall  piece  of  magnet  from  St.  Domingo,  on 
which  Odlahedrons  are  diftinguifliabie.  We  likewife  read,  in 
the  General  Hiftory  of  Voyages,  that  at  twenty  leagues  from 
Solikamfkai  in  Siberia,  magnets  are  found  of  a  cubical  form 
and  greenifh  colour,  of  a  lively  brilHant  appearance,  which  are 
reducible  into  glittering  fcales  by  pulverizing. 

The  magnet  varies  in  its  quantity  of  metal.  Thofe  of  Swe- 
den and  Siberia  are  very  rich  in  iron  ;  but  the  magnetick  force 
is  not  in  proportion  to  the  iron  they  contain. 

There  is  reafon  to  think  that  the  magnetick  agent  is  a  modi6.* 
cation  of  the  eledtrick  power.  i.  Iron  which  remains  a  long 
time  in  an  elevated  pofition  becomes  magnetick.  2.  Inflru- 
ments  of  iron  ftruck  with  lightning  are  ufually  magnetized. 
3.  Two  pieces  of  iron  may  be  magnetized  by  rubbing  them 
againfl:  each  other  in  the  fame  direction.      4.  Black  iron  ores 


Decompofition  of  Pyrites.  33^ 

are  found  in  Sweden  which  are  attra(fled  by  the  magnet,  and 
whole  metallick  particles  are  fometimes  fo  weakly  conneQed  to- 
gether that  they  are  reducible  into  powder.  We  liave  feveral 
fpccies  of  thefe  ores  in  Languedoc. 

This  fpecies  is  in  general  very  rich^  'and  affords  near  eighty 
pounds  of  iron  per  quintal. 

5.  Iron  appears  to  exift  in  the  metallick  (late  in  fome  other 
fpecies,  fuch  as  the  fpecular  iron  ore.  But  the  metallick  ftate  is 
Icfs  evident  and  charaifteriflick,  the  metallick  qualities  being 
more  changed  ;  and  thefe  ores  are  lefs  attracted  by  the  magnet. 

Thefe  iron  ores  frequently  exhibit  metallick  plates  of  a  brill- 
iancy equal  to  that  of  fteel,  and  unalterable  in  the  air.  The 
ore  of  Mont  d'Or,  that  of  Framont  in  the  principality  of  Salm, 
and  thofe  of  the  mountains  of  Vofges,  have  afforded  us  very 
curious  fpecimens.  Thefe  plates  are  fometimes  hexagonal, 
formed  by  two  hexahedral  pyramids  truncated  near  their  bafe. 

The  fpecular  iron  ore  of  Framont  afforded  Mr.  Sage  fifty- 
two  pounds  of  iron  in  the  quintal :  the  iron  is  very  ductile,  and 
acquires  much  fibre. 

The  celebrated  iron  ore  of  the  ifland  of  Elbe  is  of  tliis  kind, 
but  it  has  not  the  plated  form.  Its  cryftals  are  lenticular,  with 
brilliant  facets,  which  are  dodecahedrons  with  triangular  planes. 
Thefe  beautiful  groupes  of  cryftals  are  fometimes  fliaded  with 
tlie  mofl  lively' colours.  White  clay,  rock  ci-yflal,  cupreous 
pyrites,  &c.  are  found  among  them. 

The  Lucquefe  work  this  ore  in  the  Catalan  method,  by  flrat-^ 
ifying  charcoal  and  the  ore,  one  layer  over  the  other.  The  fire 
is  kept  up  by  good  bellows  ;  and  when  all  the  coal  is  confum- 
ed,  the  iron  is  found  colle<fled  together  in  a  mafs,  which  is  car- 
ried to  the  hammer. 

The  eifenman  is  a  fcaly  fpecular  ore.  When  it  is  rubbed, 
brilliant  particles  are  detached  from  it  *,  which  has  caufed  the 
miners  of  Daiiphiny  to  give  it  the  name  of  Luifard. 

The  eifenram  is  an  iron  ore  of  a  brilliant  red  colour,  which 
contains  plumbago  and  iron. 

ARTICLE    II. 

Concerning  Sulphureous  Iron  ores,  or  the  Sulphurs  of  Iron. 

The  union  or  combination  of  iron  and  fulphur  forms  the  ful- 
phureousiron  ore,  martial  pyrites,  fulphure  of  iron  &c.  Thefe 
fulphures  are  very  abundant,  and  are  evidently  formed  by  the 
decompofition  of  vegetables.  I  have  feveral  times  found  pieces 
of  wood  buried  in  the  u^.rth  perfefily  incrufled   with   pyrites. 


33^  Decompofitlon  of  Pyritef, 

The  effect  of  fubterraneous  fires  is  owing  only  to  the  mixture 
of  thefe  fulphures  with  the  remains  of  vegetables.  Thofe  fpe-^ 
cies  of  coal  which  efHorefcs  in  the  air,  owe  their  decompofition 
only  to  the  pyrites  with  which  they  are  penetrated.  It  is  like- 
wife  to  the  decompofirion  of  the  pyrites  that  we  mufl  refer  the 
the  heat  of  mofl  mineral  waters.  The  fulphure  of  iron  fome- 
times  cryflallizes  in  cubes,  and  often  in  o6iahedrons.  The  un- 
ion of  a  number  of  o6lahedral  pyramids  with  their  points  to- 
wards a  common  centre,  forms  the  globular  pyrites. 

When  the  fulphur  is  diiTipated,  it  fometimes  happens  that  the 
pyrites  lofes  neither  its  form  nor  its  weight.  It  then  becomes 
brown,  is  attracted  by  the  magnet,  and  is  called  the  Brown  or 
Hepatick  Iron  Ore. — See  D*"-  Lifle. 

But  the  decompofition  of  pyrites  molt  commonly  produces  the 
fulphurick  acid,  which  feizes  the  iron,  difiblves  it,  and  forms  an 
cfilorefcence  on  the  furface.  Advantage  has  even  been  taken  of 
this  property  of  the  pyrites  to  effcablifli  manufactories  of  fulphate 
of  iron,  or  copperas.  The  two  valuable  eflablilhments  M'hich 
have  been  made  of  this  kind,  in  the  vicinity  of  Alais,  work  cer- 
tain firata  of  a  hard  ponderous  pyrites.  Thefe  are  formed  into 
heaps  upon  areas,  where  the  ground  is  flightly  inclined.  The 
efHorefcence  is  accelerated  by  watering  the  pyrites,  grofsly  bro- 
ken, with  water.  This  fluid  difiblves  all  the  fait  which  is  form- 
ed, and  carries  it  into  refervoirs,  where  the  folution  fuifers  all 
the  foreign  matters  it  may  contain  to  fabfide.  It  is  left  at  reft 
in  thefe  refervoirs,  in  which  the  fun  produces  a  flight  concen- 
tration of  the  fluid  ;  and  the  concluding  evaporation  is  madeJ 
in  leaden  cauldrons,  with  the  addition  of  old  iron,  to  faturatd 
the  acid  with  as  much  of  that  metal  as  poflible.  The  '^vyftalli-k 
zation  is  performed  in  bafons,  in  which  pieces  of  wood  are  dif- 
pofed  to  afliH:  the  formation  of  cryilals.  Thefe  two  manufacto- 
ries in  Languedoc  are  capable,  in  thfdr  prefent  (late,  of  furnifh- 
upwards  of  forty  thoufand  quintals  of  copperas,  if  the  demand 
required  it. 

In  order  to  facilitate  the  vitriolization,  it  is  necefiary  to  givcj 
accefs  to  the  air,  becaufe  the  concurrence  of  this  element  is  nec- 
eaary  to  form  the  fulphurick  acid. 

The  fulphate  of  iron  cryflallizes  in  rhomboids. 

It  efBorefces  in  the  air  and  gradually  lofes  its  fine  gresn  col- 
cur  by  thediflipaticn  of  its  v/ater  of  crylhillizaiion. 

If  the  falphiti  of  iron  be  expofe  I  to  heat,  it  liquefies,  boils, 
becomes  thick,  and  is  reduced  into  powder.  This  powdery 
mixed  v.'ith  pulverized  nut-galls,  forms  a  dry  ink,  which  fever-* 
al  perfons  fell  as  a  fecrer,  and,  which  requires  only  the  addition 
of  water  to  render  it  fit  for  ufe. 


Spathofe  Iron  Ores,  337 

The  fame  powder  urged  by  a  ftronger  heat,  fuffers  Its  acids 
to  efcape  ;  after  which  there  remains  only  a  martial  earth,  or 
metallick  oxide,  known  by  the  name  of  Colcothar. 

I  attribute  the  formation  of  all  the  yellow  or  red  earths,  com- 
monly called  ochres,  to  a  (irailar  decompofition  of  the  pyrites. 
The  heat  produced  by  the  decompofition  of  the  pyrites  has  de« 
termined  the  refpe<n:ive  colours  of  thefe  earths  :  and  they  may 
be  caufed  to  pafs  artificially  through  thefe  various  (hades,  by 
treating  them  with  various  degrees  of  fire.  I  have  difcovei^ecl 
in  the  diocefe  of  Uzes,  banks  of  ochre  of  fuch  uncommon  fi^e- 
nefs,  and  fo  very  pure,  that  calcination  converts  it  into  a  brown 
red,  fuperiour  to  every  thing  before  known  in  trade.  The  man- 
ufactory which  has  been  eitablifhed  under  my  care,  has  acquir- 
ed all  the  celebrity  which  the  fuperiority  of  its  products  could 
not  but  neeeifarily  afford  it.  My  experiments  on  thefe  ochres, 
and  the  advantages  which  they  may  afford  to  the  arts,  may  be 
feen  in  the  work  which  i  have  publiihed  on  this  fubjedl,  print- 
ed for  Didot  the  elder,  at  Paris. 

I  likewife  found  at  Mafs-Dieu,  near  Alais,  a  flratum  of  red 
ochre  of  fo  beautiful  a  colour,  that  it  could  fcarcely  be  imitated. 


ARTICLE      III. 

Concerning  the  Spathofe  Iron  Ores,  or  Carbonates  of  Iron. 

The  carbonick  acid  is  fometimes  combined  with  iron  in  ores  ; 
snd  the  refemblance  between  this  iron  and  fpar,  has  procured  it 
the  name  of  the  Spathofe  Iron  Ore. 

The  formation  of  this  ore  appears  to  be  owing  to  the  mutu- 
al decompofition  of  the  carbonates  <  f  lime,  and  the  fulphates  of 
iron.  A  folution  of  copperas,  in  which  calcareous  fpar  was  fuf- 
fered  to  remain,  produced  this  ore,  according  to  the  experi- 
ments of  Mr.  Sage. 

Bergmann  obtained  froTi  the  ores  of  this  kind,  which  he  an- 
alyzed, thirty-eight  ounces  of  the  oxide  of  iron,  twenty-four 
ounces  of  the  oxide  of  manganefe,  and  fifty  ounces  of  calcare- 
ous earth.  It  appears  therefore  that  this  ore  contains  two  met- 
als united  by  a  calcareous  cement,  which  cryftallizes  always  in 
its  own  form,  as  we  find  in  the  lapis  calaminaris,  the  calcareous 
grit,  &c. 

The  fpathofe  iron  ores  are  wrought  at  Cafcaftle,  in  the  dio- 
cefe of  Narbonne,  at  Bendorf  on  the  banks  of  the  Rhine,  Eifen- 
artz  in  Styria,  &c. 
2...T 


53^'  ^^g  ^f^^  of  Iron,' 

ARTICLE      IV. 

Concerning  the  Bog  Ores  of  Iron,  or  Argillaceous  Iron  Ores,- 

Thefe  ores  confift  merely  of  a  martial  oxiiJe,  in  a  (late  o£ 
greater  or  lefs  purity,  mixed  with  earthy  fubftances  of  the  nature- 
of  clays. 

They  appear  to  have  been  depofited  by  water ;  and  are  lifuallv 
difj()ofed  in  flrata,  which  are  frequently  marked  out,  and  as  it 
were  feparated,  into  fmall  prifms,  whofe  formation  arifes  fimply 
from  the  flirinking  of  the  clay. 

1.  The  eagle-ftone,  or  letites,  ought  to  be  ranked  among  the 
bog  ores  of  iron.  They  are  geodes  of  a  round  oval  form, 
haing  a  hard  e^cternal  covering,  while  the  cavity  includes  a  de- 
tached nodule  ;  and  thenoife  produced  by  (baking  one  of  thefe 
ftones,  arifes  from  the  nodule  being  at  liberty  to  move  within  the 
ilone. 

The  name  of  eagle-flbne  has  arifen  from  a  notion,  formerly 
entertained,  that  eagles  placed  it  in  their  nefts  to  facilitate  the 
laying  of  their  eggs  ;  and  wonderful  powers  of  rendering  labours 
fafe  and  eafy,  were  attributed  to  it  in  the  times  of  fuperflition. 

2.  We  are  acquainted  with  an  iron  ore  in  round  pieces,  re- 
fembUng  bullets,  of  feveral  lines  in  diameter,  which  ought  to  be 
confidered  as  a  Variety  of  the  preceding.  An  ore  of  this  kind 
was  begun  to  be  wrought  at  Fontanez,  near  Sommieres  ;  and  we 
find  a  confiderable  quantity  of  thefe  metallick  globules  among 
our  red  earths  in  the  neighbourhood  of  MontpelJier. 

3.  The  purelt  oxide  of  iron,  worn  and  carried  along  by  waters, 
and  afterwards,  depofited,  forms  (Irata  of  various  appearances 
and  colours.     Thefe  are  called  hrematites. 

The  colours  arife  from  the  various  degrees  of  alteration  in  the 
oxide.  They  vary  from  yellow  to  the  decpeft  red.  The  red 
haematites  is  ufed  in  the  arts  to  buniifti  gold  or  filver.  It  is  cut 
into  long  pieces,  which  whenpolifhed  arc  known  by  the  name 
of  burnilhers.  This  blood- Rone  is  fometimes  foft  enough  to  bs' 
ufed  inftead  of  a  crayon  for  drawing. 

Its  figure  is  likewife  fubjcift  to  prodigious  variation.  It  ofterv 
appears  as  if  compofed  of  fmall  prifms  applied  one  agaiufl:  the 
other,  in  which  cafe  it  is  called  the  fibrous  haematites.  In  other 
fpecimens  it  is  tuberculated.  It  is  very  frequently  found  in 
compadl  irregular  mafles,  fuch  as  thofe  of  the  ores  of  the  county 
of  Foix.  This  muft  naturally  exhibit  the*  fame  variety  of  fonrivS 
as  the  calcareous  ftalai^ites,  becaufe  its  mode  of  formation-  i» 
Bcarly  the  fame. 


sBlumhago,  or  B/oifk   Lead*  .33^ 

ARTICLE    V. 

t3oncenling  Nauve  Pruffian  Blue,  or  the  PruiTiatc  of  iron. 

Beccer  fpenks  of  a  blue  earth  found  at  Turliige.  Henckel 
^informs  us  that  a  blue  martial  earth  is  found  at  Schneeburg  and 
4it  Eibenftock.  Cronftedt  has  defcribed  a  native  Pruffian  Blue  ; 
Mr.  Sage  found  it  in  the  turf  of  Picardy.  It  is  like  wife  found 
:^n  Scotland,  in  Siberia,  &c.  and  I  polTefs  a  fulphur  of  iron  in  ?. 
•itate  of  decompofition,  which  exhibits  a  true  prufliate  of  irpn 
,ypoa  one  of  its  furfaces. 

ARTICLE      VL 

Concerning  Plumbago,  or  the  Carbure  of  Iron. 

The  name  of  Plumbago  is  at  prefent  confined  to  that  {hitiing 
vfubi1:ance  of  a  blackifh  blue  colour,  which  is  ufed  to  make  the 
pencils  called  black-lead  pencils.  It  has  a  greafy  feel,  exhibits 
a  tuberculated  fradture,  foils  thehands,  and  leaves  a  black  trace 
upon  paper. 

Plumbago  is  found  in  many  places  ;  that  of  commerce  is 
brought  to  us  from  Germany.  We  receive  it  likewife  from 
Spain,  from  America,  and  from  England.  It  is  alfo  found  in 
■France.  This  mineral  is  almoft  always  difpofed  in  feparate 
maflcs  in  the  bowels  of  the  earth  j  and  it  is  probably  on  account 
of  this  form,  that  the  ancients  denoted  it  by  the  words  Glebse 
3?lumb  arise. 

The  plumbago  of  England  differs  from  the  other  fpecimens 
in  its  texture,  which  is  much  finer,  and  of  a  greater  degree  of 
brilliancy.  The  Englifh  do  not  take  a  larger  quantity  out  of  the 
mine  than  the  market  demands,  in  which  they  are  careful  to 
4ceep  up  the  price. 

The  mofl  plentiful  mine  is  in  the  county  of  Cumberland. 

The  plumbago  of  Spam  is  always  accompanied  with  pyrites, 
which  efflorefce  on  the  furface  of  the  pieces  5  either  in  fmall 
xryftals,  fimilar  to  thole  of  the  fulphate  of  iron  ;  or  in  a  kind 
of  filky  vegetation,  analogous  to  that  of  plume  alum.  It  is  dug 
•up  in  the  neighbourhood  of  the  town  of  Ronda,  at  the  diilance 
x>f  four  leagues  from  the  Mediterranean  fea.  It  is  the  vi^orft:  kind 
which  comes  to  market  and  i§  ufed  only  to  give  a  fliining  black 
colour  .to  iron  utenfils. 


34®  PhwihagOi  or  Black  Lead. 

The  American  plumbago,  which  Mr.  Woulfe  procured  frort^ 
Mr.  Pelletier,  breaks  eafily,  and  exhibits  fmall  quartzofe  grains 
in  its  internal  part,  as  well  as  flight  traces  of  a  whitilh  clay.  It 
is  found  in  feparate  mafl^es  ;  and  its  texture  appears  to  confift  of 
the  union  of  an  infinity  of  fmall  fcaly  parts,  which  at  (irft  fight 
might  caufe  it  to  be  taken  for  molybdena. 

France  likewife  pofl^elfes  plumbago,  and  the  chevalier  Lama- 
non  obferved  it  in  Upper  Provence.  The  mine  is  fituated  near 
Col.  de  Bleoux.  The  black  lead  is  found  between  two  ftrata 
of  clay,  not  more  than  a  few  lines  in  thicknefs.  It  forms  a 
flratum  of  four  inches  thick  ;  or  rather  the  ftratum  confifts 
of  feparate  mafles,  which  are  fometimes  feveral  feet  in  length. 
It  is  accompanied  by  a  vein  of  pyrites.  The  inhabitants  of 
Blecwx  fell  this  produ6l  at  Marfeilles  at  about  fifteen  livres  per 
quintal.  Mr.  de  la  Peyroufe  found  plumbago  with  tourmalihes, 
in  the  county  of  Foix,  and  Mr.  Darcet  brought  it  from  the  Py- 
lenean  Mountains. 

Plumbago  is  indeftruftible  by  heat  without  the  prefence  of 
■air.  Mr.  Pelletier  expofed  it  to  diftillation,  in  the  pneumato,- 
chemical  apparatus,  by  a  violent  fire  during  fix  hours,  without 
the  plumbago  having  lolt  weight,  or  fufl^ered  any  other  change. 
He  expofed  two  hundred  grains  in  a  well-clofed  porcelain  cru- 
cible to  the  fire  of  the  manufactory  at  Seves,  and  it  loft  only 
ten  grains.  But  when  it  is  calcined  with  the  concurrence  of 
sir,  it  then  burns,  and  leaves  but  a  fmall  quantity  of  refidue. 
Meflrs.  Quift,  Gahn,  and  Hielm  obferved  that  one  hundred 
grains,  treated  under  a  muffle  in  a  ihallow  veflel,  left  only  ten 
grains  of  oxide  of  iron.  Mr.  Fabroni  difllpated  the  whole  of 
a  portion  of  plumbago  expofed  under  the  muffle.  This  calcina- 
tion is  a  flow  combullion,  which  is  facilitated  by  caufing  the 
matter  to  prefent  a  large  furface,  and  agitating  it  from  time  to 
time. 

If  one  part  of  plumbago,  and  two  of  very  cauftick  dry  alkali, 
be  heated  in  a  retort  with  the  pneumato-chemical  apparatus, 
the  alkali  becomes  effervefcent,  hydrogenous  gas  is  obtained,  and 
the  plumbago  difappears.  This  beautiful  experiment  proves 
that  the  fmall  quantity  of  water  contained  in  the  fait  is  decom- 
pofed  ;  and  that  its  oxigene,  by  combining  with  the  carbong 
of  tive  piumbngo,  forms  the  carbonick  acid.  The  experiment 
publiOrved  by  Scheele  has  been  repeated  and  confirmed  by  Mr. 
Pcll^iler. 

The  fulphurick  acid  does  not  2,0i  upon  plumbago,  according 
to  Scheele.  Mr.  Pelletier  has  obferved  that  one  hundred  grains 
of  plumbago,  and  four  ounces  of  the  oil  of  vitriol,  being  digeUed 
in  the  cold  for  feveral   mouths,  the  acid  acquired  a  green  col- 


Plumbago  J  or  Black  Lead,  34 1 

feur,  and  the  property  of  congealing  by  a  very  flight  degree  of 
cold.  The  fulphurick  acid  diflilled  from  piumbagc,  pafles  to 
the  ftate  of  the  fulphureous  acid  ;  at  the  fame  time  that  carbon- 
ick  acid  is  obtained,  and  an  oxide  of  iron  is  left  in  the  retort. 

The  nitrick  acid  has  no  a(flion  upon  plumbago  unlefs  it  be 
impure.  Eight  ounces  of  nitrick  acid,  diltilled  from  half  a  gros 
of  purified  plumbago,  neither  altered  its  fliining  appearance,  nor 
deprived  it  of  its  unduous  feel. 

The  muriatick  acid  diflblves  the  iron  and  the  clay  which  con- 
taminate native  plumbago.  MelTrs.  Berthollet  and  Scheele  a- 
vailed  themfelves  of  this  method  to  purify  it.  The  liquor  being 
decanted  a  fter  digeftion  upon  the  plumbago,  the  refidue  is  then 
wafhed,  and  fubmitted  to  diftillation  to  feparate  the  fulphur. 
The  muriatick  acid  alone  has  no  a£lion  upon  plumbago,  but  the 
oxigenated  muriatick  acid  diflblves  it  -,  the  refult  being  a  true 
combuftion  effeded  by  the  oxigenc  of  the  acid,  and  the  carbone 
of  the  plumbago. 

If  ten  parts  of  the  nitrate  of  pot-afli  be  fufed  in  a  crucible, 
and  one  part  of  plumbago  be  thrown  thereon  by  a  little  at  a  time 
the  fait  will  deflagrate,  and  the  plumbago  will  be  deflroyed. 
The  matter  which  remains  in  the  crucible  confifts  of  very  etfer- 
vefcent  alkali,  and   a  fmall  portion  of  martial  ochre. 

If  plumbago  be  diltilled  with  muriate  of  ammoniack,  the 
muriate  fublimes,  coloured  by  the  iron. 

All  tliefe  fads  prove  that  plumbago  is  a  peculiar  combuftible 
fubfliance,  a  true  charcoal  combined  with  a  martial  bafis.  Plum- 
bago is  more  common  than  is  imagined.  The  brilliant  char- 
coal of  certain  vegetable  fubitances,  more  efpecially  when  for- 
med by  din:iilation  in  ck>fe  vefiels,  poflefles  all  the  charaders 
of  plumbago.  The  charcoal  of  animal  fublfanccs  pofleffes  char- 
aders  ftill  more  peculiarly  refembling  it.  Like  it  they  are  diffi- 
cult to  incinerate,  they  leave  the  fame  imprclTion  on  the  hands 
and  upon  paper  ;  they  iikcwife  contam  iron,  and  become  con- 
verted into  cavbonick  acid  by  combuftion.  When  animal  fub- 
ftances  are  dilliiled  by  a  ftrong  lire,  a  very  fine  powder  fublimes, 
which  attaches  itfelf  to  the  inner  part  of  the  neck  of  the  retort. 
This  fubllance  may  be  made  into  excellent  black-lead  pencils, 
as  I  myfclf  have  proved. 

Carbone  may  be  formed  in  the  earth  by  the  decompofition  of 
wood  together  with  pyrites  •,  hwt  the  origin  of  plumbago  ap- 
pears to  me  to  be  principally  owing  to  the  ligneous,  and  truly 
indecompofiible,  part  of  the  wood,  which  refills  the  deltrudive 
adion  of  water,  in  its  decompofition  of  vegetable  fubftances. 
This  ligneous  fubftance  difengaged  from  the  other  principles, 
mud  form  peculiar  depofitions  ami  Itrata  j  and  sMr.  Fabroni 
Jifis  aflfured  me  that  the  formation  of  plumbago    in  water   is  a 


14*  PlumhagOt  or  Black  Lead, 

ccminon  phenomencn,  of  which  he  had  feveral  tnues  been  ^ 
wJtnefs.  This  chemiil  by  his  letter  of  the  thirtieth  of  January, 
1787,  inforrxis  me  that,  in  the  dominions  of  the  king  of  Naples, 
there  are  weiir,  dug  exprefsjy  for  the  piirpofe  of  collecting  an  a- 
cidulous  water,  at  the  botrcm  of  which  welis  a  quantitv  of  plum- 
bago is  collecled  every  fix  months. 

He  fuppofes  that  the  black  mud  which  13  found  beneath  the 
pavements  of  Paris  is  plumbago  formed  in  the  humid  way. 

There  are  likewife  diilricls  in  Tufcany  where  plumbago  ie 
formed  in  the  humid  way. 

This  fubftance  is  of  confiderableufe  in  the  arts.  It  has  beea 
at  all  times  applied  to  the  purpofe  of  making  pencils,  the  moft 
efteemed  of  v/hich  are  thofe  which  come  from  England.  They 
are  made  at  Kefwickin  the  county  of  Cumberland*  The  piece 
of  plumbago  is  f.iwed  into  very  thin  plates.  The  edge  of  one 
of  thefe  plates  is  fitted  into  a  groove  ilruck  in  a  wooden  cylind- 
er ;  and  the  thin  plate  of  plumbago  is  then  cut  off  in  fuch  ^ 
manner  that  the  cavity  of  the  fmaJi  cylinder  remains  perfectly 
billed. 

The  duft  cf  plumbago  is  ufed  to  lubricate  certain  infcr^ments, 
and  it  is  likewife  made  into  pencils  of  an  inferiour  quality,  by 
kneading  it  up  with  mucilage,  or  by  fufing  it  with  fulphur. 
The  fraud  mayeafdy  be  difcovered  by  the  affiflance  of  fire, 
which  burns  the  fulphur  ;  or  by  means  of  water,  which  diflblves 
the  mucilage. 

Plumbago  16  likewife  wfcd  to  defend  iron  from  rufi:.  The 
iiearths  and  plates  of  chimneys,  and  other  fimilar  utenfils,  which 
appear  very  bright  owe  their  colour  to  plumbago.  Homberg 
Aias  communicaied  a  procefs,  in  the  year  1699,  in  which  plum- 
b.-igo  is  applied  to  this  uie.  Eight  pounds  of  hogs-lard  are  melt- 
ed with  a  fm  all -quantity  of  water,  vt'ith  the  addition  of  four  ounc- 
es of  camphor.  When  this  lail  is  fufed,  the  mixture  is  taken 
from  the  lire  ;  and  while  it  is  yet  hot,  a  fmall  quantity  of  plum- 
bago is  added,  to  give  it  a  leaden  colour.  When  this  is  to  bs 
applied,  the  ut^nfils  muft  be  heated  to  fuch  a  degree,  that  the 
hand  can  fcarcely  be  applied  to  them.  \n  this  (late  the  compo- 
iition  muft  be  rubbed  on  them,  and  afterwards  wiped  when  the 
{)iece  is  dry. 

Thofe  who  prepare  fmall  Hint,  makeufe  of  black  lead  to  pol- 
ifli  and  glaze  it  ;  the  fhot  is  rolled  or  agit<.ted  together  with  a 
quantity  of  plumbago.  Plumbago  is  likewife  ufed  to  make  ra- 
zor ftrops.  When  kneaded  up  with  clay,  ft  forms  excellent 
crucibles,  which  we  receive  from  PaJaw  in  Saxony.  One  part 
of  plumbago,  three  of  argillaceous  earth,  and  a  fmall  quantity 
of  cow's  dung  very  linely  chopped,  form  an    excellent   iiite  fc;? 


Affa^  of  Iron  Ores,      Jr 


S-\y 


^torrs.  ]^^r.  Pelletier  has  ufeci  it  with  great  advantagie.  This 
Jute  is  exceedingly  refratlory  ;  and  the  glafs  wiil  melt  without 
the  covering  changing  its  form. 

To  make  the  aflay  of  an  iron  ore,  I  find  the  following  flux 
very  advantageous  :— I  mix  four  hundred  grains  of  calcined 
borax,  forty  grains  of  flacked  lime,  two-  hundred  grains  of  ni- 
trate, and  two  hundred  of  the  ore  to  be  aflayed.  I  pulverize 
^his  mixture  and  place  it  in  a  lined  crucible,  which  I  cover.  The 
heat  of  a  forge  furnace  is  fulTicient  to  efFe£):  the  redudion.  In 
the  fpace  of  half  an  hour,  the  button  of  metal  is  found  depofited 
at  the  bottom  of  the  vitrified  flux. 

The  procefs  for  working  iron  mines-  varies  accof cFing  to  the 
nature  of  the  ore.  The  metal  is  fometimes  fo  little  altered,  and 
fo  abundant,  that  nothing  more  is  neceffary  than  to  mix  it  with 
the  coal,  and  fufe  it.  This  fmipk  and  economical  procefs  forms 
the  bafis  of  the  Catalan  method,  which  ir^ay  be  employed  ia 
treating  the  fpathofe  iron  ores,  thofe  of  Elb«,  the  h?smatites,  and 
ether  lich  and  pure  ores.  But  it  cannot  be  applied  ro  fuch  as 
contain  much  foreign  matter  capable  of  becoming  converted  mio- 
ilag.  For  this  reafon,  the  experiments  made  in  the  county  of 
Folx  on  the  ores  of  various  countries,  and  varloua  qualities, 
have  not  fucceedcd.  On  this  head,  the  work  of  Mr.  De  la  Pey- 
ioufe,  and  the  Memoirs  of  the  Baron  de  Dietrich,  Oisv  be  con- 
fulted. 

The  furnaces  in  which  iron  Is  fu fed,  are  from  twelve  to  eigh- 
teen feet  in  height.  Their  internal  cavity  has  the  form  of  two 
four-lided  pyramids  joined  bafe  to  bafe.  The  only  iiux  added 
to  the  ore  is  the  calcareous  flone,  named  (by  the  French)  cajline^ 
^f  the  ore  be  argillaceous  ;  but,  if  the  gangue  be  calcareous,  the 
the  workmen  employ  argillaceous  earth,  which  is  named  herbue. 

The  furnace  is  charged  at  the  upper  part  \  and  the  fire  is  ex- 
cited by  bellows,  or  hydraulick  machines.  The  ore  melts  as  it 
pafies  through  the  coal  and  is  collecfled  at  the  bottom,  where  it 
is  maintained  in  a  liquid  ftate.  At  the  end  of  every  eight  hours 
it  is  fulFcred  to  flow  out  into  the  mould,  or  hollow  channel  made 
in  the  fand. 

Crude  iron,  cad  in  fuitable  moulds,  forms  chimney-backs, 
pots,  cauldrons,  pipes,  and  an  infinity  of  utcnfiis  or  vafes,  which 
could  not  be  obtained  without  difficulty  by  forging  the  iron. 
The  works  which  are  eftabliflied  at  Creufotin  Burgundy  furpafs 
every  thing  wliich  can  be  defircd  in  this  fpecie,  of  induftry. 

This  fir(i:  product  is  called  Caft  or  Crude  Iron.  It  is  brittle  y 
but  may  be  rendered  duclile  by  heating  it  agai«,  and  hammer- 
hig  it.  For  this  purpofe  the  pig  iron  is  fufed  agnin,  and  iiirred 
while  in  the  (late  of  fuGon  :  after  which  i:  is  carried  to  the  for£« 


344 


Crude  or    Ca/I  Iron. 


hammer.  By  this  treatment  the  iron  becor^ies  duclile,  afiumcs 
a  fibrous  texture,  and  is  formed  into  fquare  or  flat  bars  for  the 
purpofes  of  trade. 

Iron  is  likewife  capable  of  a  degree  of  fuperiority,  which  is 
given  to  it  by  placing  it  in  conta^l  with  coaly  fubftances,  and 
foftening  it  to  fuch  a  degree  that  thefe  may  penetrate  into  its 
texture.  It  is  then  known  by  the  name  of  Steel.  We  are  in- 
debted to  Mr.  Jars  for  very  interefting  accounts  of  the  fteel 
manufactories  in  England.  The  manufa£lory  eftablifhed  at 
Amboife  is  not  inferiour  to  thofe  of  England,  as  was  afcertained 
by  comparative  experiments  made  upon  the  producfls  of  the  fev- 
eral  manufa£lories,  at  Luxemburg,  on  Friday  the  7th  of  Septem- 
ber, 1786. 

We  may  therefore  divide  the  different  ftates  of  iron  into  caft 
or  crude  iron,  iron  properly  fo  called,  and  fteel.  It  is  clear  that 
thefe  three  ftates  are  nothing  more  than  modifications  of  each 
other  ;  but  the  circumftances  on  which  they  depend,  and  the 
principle  which  eftabliihes  their  difference,  were  till  lately  un- 
known. 

The  celebrated  Bergmann  has  given  an  analyfis  of  the  vari- 
ous ftates  of  iron,  and  has  drawn  up  the  following  table  : 


Inflammable  Air 
Plumbago 
Manganefe 
Siliceous  Earth 
Iron 


Caft  Iron. 

Steel. 

1  40 

48 

2        20 

0      50 

15     25 

2        25 

15      25 
0      60 

80        30 

83   65 

Iron. 

50 
o 

o 

84 


12 

45 


This  celebrated  chemift  has  confirmed  by  his  refults  the  con- 
clufion  of  Reaumur,  who  always  confidered  fteel  as  an  interme- 
diate ftate  between  crude  and  malleable  iron. 

We  are  indebted  to  three  French  chemifts,  Mefirs.  Monge, 
Vandermonde,  and  Berthollet,  for  a  quantity  of  much  more 
accurate  information  refpeding  all  thefe  ftates. 

We  mav  confider  iron  ores  as  natural  mixtures  of  iron,  oxi- 
gene,  and  various  foreign  fubftances.  When  an  ore  is  wrought 
the  objeiSt  of  the  operator  is  to  clear  the  iron  of  all  thefe  mat- 
ters. To  effect  this  feparation,  the  ore  is  thrown  into  the  fmelt- 
ing  furnaces,  with  different  proportions  of  charcoal.  Thefe  mat- 
ters are  heated  together  until  they  arrive  at  the  hotteft  part, 
where  the  mixture  falls  •,  7\rn\j  after  fuffering  the  ftrong  adion 
of  the  fire,  is  pr^ipitated  in  fufion,  and  forms  a  fluid  mafs  at 
the  bottom  of  the  furnace.  The  earths  and  ftones,  nearly  in  a 
vitrified  ftate,  float  above  the  fluid  ;    and    the   oxigcne,   being 


Various  States  of  Iron.  ^4^ 

partly  driven  out,  remains  likewifc  in  gre.iter  or  lefs  quantity  in 
the  crude  iron.  The  crude  iron  is  either  white,  or  grey,  or  black. 
In  our  enquiries  concerning  the  caufe  of  thefe  three  kinds  of  i- 
ron,  and  their  qualities,  we  can  refer  them  only  to  the  propor- 
tions of  foreign  principles  contained  in  the  crude  iron.  Thefe 
principles  are  carbone  and  oxigene. 

I.  Crude  iron  contains  carbone.  The  ladles  which  are  i^fed 
to  agitate,  take  up,  and  pour  out  this  melted  metal,  become  cov- 
ered with  a  coating  of  plumbago,  which  contains  nine  tenths  of 
carbone  :  and  caft-iron,  flrongly  heated  in  contadl  with  the 
coal,  fufFers  a  part  to  efcape  or  exude  from  its  furface  when  it 
is  flowly  cooled.  Crude  iron  emits  fparks  when  it  is  heated  : 
the  acids  which  diflblve  it  always  leave  a  refidue  which  is  pure- 
ly carbonaceous.  The  hydrogenous  gas,  which  is  obtained  by 
treating  thefe  irons  v/ith  acids,  always  affords  the  carbonick  acid 
by  combuftion. 

2.  Crude  iron  contains  oxigene.  Several  mineralogifls  at- 
tribute the  fragility  and  brilliancy  of  crude  iron  to  its  ftill  con- 
taining iron  in  the  ftate  of  oxide.  This  opinion,  which  is  gen- 
erally adopted,  fuppofes  the  exiftence  of  oxigene.  Crude  iron 
urged  by  a  violent  heat  in  clofe  vefTels,  affords  the  carbonick  acid 
and  palTes  to  the  ftate  of  fofc  iron  j  becaufe  its  oxigene  then  u- 
nites  to  the  carbonaceous  principle,  and  conflitutes  the  carbon- 
ick acid,  which  exhales,  and  clears  the  crude  iron  from  the  two 
principles  which  altered  its  quality. 

Oxigene  and  carbone  exift  therefore  in  crude  iron,  but  they 
may  exift  in  three  diiTerent  ftates — i.  A  large  quantity  of  car- 
bone, and  a  fmall  quantity  of  oxigene.  2.  An  exad:  propor- 
tion between  thefe  two  principles.  3.  Much  oxigene  and  a 
fmall  quantity  of  carbone. — Now  we  find  thefe  three  ftates  in 
the  three  kinds  of  crude  iron  which  we  have  diftinguifhed,  as  is 
proved  by  analyfis  \  and,  as  we  may  judge  by  the  fecondary 
procefles,  to  correal  thefe  imperfections,  or  to  convert  cruJe 
iron  into  the  malleable  ftate. 

1.  In  the  firft  cafe,  that  iron  which  contains  an  excefs  of  car- 
bone is  agitated  or  ftirred  as  it  flows  out.  It  is  kept  a  lon;^ 
time  expofed  to  the  a(£lion  of  the  bellows,  and  the  fmalleft  Doffi- 
ble  quantity  of  charcoal  is  made  ufe  of.  We  fee  that  in  this 
procefs  the  propereft  methods  are  ufed  to  facilitate  the  combuf- 
tion of  this  excefs  of  the  carbonaceous  principle. 

2.  In  the  fecond  cafe,  that  kind  of  iron  in  which  the  princi- 
ples exift  in  accurate  proportions,  requires  only  the  a£l;ion  of 
heat  to  unite  and  volatilize  the  two  foveij^n  principles.  The  crude 
iron  is  put  into  a  ftate  of  ebullition- by  the  difongagementof  the 
lAcid  Aviiich  isforn^tf!.  .,iiid  ex'v'r-v 

'1...V  ' 


34^  Various  States  of  Iron, 

3.  In  the  third  kind,  or  that  which  contains  oxigene  in  ex- 
cefs,  the  bellows  are  urged  lefs  violently ;  and  the  metal  is  pen- 
etrated with  coal  in  order  to  combine  with  the  oxigene.  Here 
therefore  we  fee  theory  and  pra-tlice  go  together.  The  former 
explains  the  ufual  manipulations,  and  affords  us  principles  in 
cafes  wherein  experiment  too  frequently  fails. 

Steel  is  a  kind  of  iron  which  contains  carbone  only  ;  and  its 
exiftence  may  be  proved  by  all  the  experiments  which  have  been 
mentioned  as  demonilrations  that  crude  iron  contains  it. 

Carbone  may  be  given  to  iron — i.  In  the  fufion  of  the  ore. 
2.  Or,  afterwards,  by  the  cementation  of  iron  with  coaly  fub- 
ilances. 

1 .  In  fome  parts  of  Hungary,  and  in  the  county  of  Foix,  iron 
ores  are  wrought  which  contain  the  metal  nearly  in  the  difen- 
gag<?d  ftate  ;  and  the  cafl  iron,  when  duly  hammered,  affords 
iron  and  fteel  in  a  greater  or  lefs  quantity,  according  to  the 
management  of  the  fire,  the  quantity  of  air,  afforded  by  the 
tuyere,  the  quantity  of  coal  made  ufe  of,  and  the  nature  of  the 
ore.  In  this  operation,  the  iron  being  fcarcely  at  all  calcined 
in  the  ore,  becomes  charged  with  coaly  matter  only,  and  the  re- 
fult  is  fteel. 

2.  If  the  coaly  principle  be  combined  with  iron  in  a  du£lilc 
ftate,  and  deprived  of  all  foreign  matter,  the  combination  being 
effe(^ed  by  a  cementation  or  otherwife,  the  iron  will  pafs  to  the 
ftate  of  fteel  ;  and  the  qualities  of  this  fteel  will  vary  according 
to  the  proportions  of  carbone.  The  purity  of  the  iron,  and  the 
care  which  is  taken  to  avoid  the  oxidation  of  the  metal,  eftablifti 
the  various  kinds  of  fteel  which  are  met  with  in  commerce. 

The  nature  and  the  principles  of  fteel  being  once  admitted 
and  eftablillied,  the  following  fatTts  will  explain  themfelves. 

1.  Since  fteel  contains  no  foreign  principle  but  Carbone,  it  is 
not  furprifmg  that  it  remains  unchanged  by  a  violent  heat  in 
clofe  veffels. 

2.  Steel,  repeatedly  heated,  and  expofed  while  hot  to  a  cur- 
rent of  air,  lofes  its  properties,  and  paffes  again  to  the  ftate  of 
foft  iron. 

3.  Steel  kept  plunged  for  a  time  in  crude  iron  in  which  oxi- 
gene predominates,  becomes  itfelf  converted  into  foft  iron. 

4.  Soft  iron  kept  for  a  time  plunged  in  crude  iron,  wherein 
carbone  predominates,  becomes  converted  into  fteel. 

5.  Iron,  by  p?!inng  to  the  ftate  of  fteel,  increafes  in  weight 
one  hundred  and  feventieth  part. 

Du£tile  iron  would  be  a  very  foft  metal,  if  it  were  cleared  of 
'all  foreign  fubilances. 


Various  States    of  Ircn.  34-7 

From  all  thefe  fadls  we  may  conclude — i.  That  crude  iron  Is 
a  mixture  of  iron,  carbone,  and  oxigene.  2.  That  the  produ6is 
of  crude  iron  arc  white,  grey,  or  black,  according  to  the  propor- 
tions of  oxigene  and  carbone  which  it  contains.  3.  That  the 
fteel  of  cementation  is  merely  a  mixture  oF  iron  and  carbone. 
4.  That  fteel  which  is  over  cemented,  is  an  iron  containing  too 
Jarge  a  quantity  of  carbone.  8.  That  iron  would  be  a  very 
foft  metal,  if  it  were  not  mixed  with  a  greater  or  lefs  quantity 
of  oxigene  and  carbone. 

Forged  Iron  is  diftinguifhed  into  foft  iron,  and  eager  or  brit- 
tle iron,  by  us  (the  French)  called  Rouvrain.  This  laft  has  a 
coarfcr  grain  than  the  other  :  it  Is  divided  into  red  fhort  iron, 
and  cold  fliort  iron.  The  caufe  of  this  phenomenon*  is  known  : 
it  arifes  from  a  phofphatc  of  iron,  which  was  difcovered  by 
Bergmann.  This  celebrated  chemifl  conftantly  obferved  a 
precipitate  to  be  formed  in  the  folutions  of  cold  (liort  iron  in  the 
fulphurick  acid.  It  was  a  white  powder,  which  he  called  Si- 
derite,  and  at  firfl  fuppofed  to  be  a  peculiar  metal  j  but  Mr. 
Meyer  of  Stetin  has  proved  that  it  is  a  true  phofphate  of   iron. 

Soft  iron  does  not  afford  it.  All  the  irons  of  Champagne 
afford  about  a  dram,  or  gros,  in  the  pound  of  iron. 

In  order  to  obtain  fiderite,  it  is  neceffary  that  the  folution 
fhould  be  faturated  by  a  gentle  heat  on  the  fand  bath.  If  the 
folution  be  made  too  quickly,  the  fiderite  is  then  mixed  with 
ochre,  which  alters  its  purity  and  whitenefs. 

A  precipitate  is  formed,  which  takes  place  fo  much  the  more 
fpeedily,  as  the  folution  is  more  diluted  with  water  each  time 
after  filtration.  The  precipitate  is  formed  in  the  firft  three  or 
four  days  ;  a  fecond  is  obtained  towards  the  fixth  day  ;  and  that 
which  afterwards  falls  down  is  mixed  with  ochre.  Siderite 
may  likewife  be  obtained  by  difTolving  ir^on  in  the  nitrick  acid, 
and  evaporation  to  drynels.  The  iron  is  oxided  by  this  firft  op- 
eration. More  nitrick  acid  being  poured  on  this  refidue,  dif- 
folves  only  the  Gderite,  without  touching  the  oxide  of  iron.  A 
fecond  evaporation  muft  then  be  made  ;  and  the  rcHdue  muft 
be  diluted  with  water,  to  evaporate  the  laft  portions  of  nitrick 
acid  :  and  that  which  remains  is  fiderite.  It  is  ibluble  in  the 
fulphurick,  nitrick,  and  muriatick  acids,  from  which  if  may  be 
precipitated  by  pouring  into  the  folution  as  much  alkali  as  is  ne- 
ceffary to  faturate  the  acid  folvent.  If  the  alkali  be  added  in  ex- 
cefs,  ochre  is.  then  precipitated  ;  and  the  refult  is  a  phofphate, 
and  a  fait  arifing  from  the  union  of  tl^.e  acid  made  ufe  of  and  the 
alkali  which  has  ferved  for  the  precipitation. 

The  fixed  and  volatile  alkalis,  and  lime  water,  decompofe 
fiderite.  It  Ig  likewife  decomposed  by  proje<^ing  it  upon  fitfcd 
witre. 


348  .     Habitudes  of  Iron. 

When  it  has  been  precipitated  by  ammonlaclr,  cryftals  may  b6 
obtained  by  evaporation,  which  when  treated  with  powder  of 
charcoal  affords  phofphorus.  The  ochreous  precipitate  affords 
iron  by  reduction  ;  it  is  therefore  a  combination  of  the  phof- 
phorlck  acid  and  iron.  Every  fokuion  of  iron  is  precipitated  in 
the  form  of  fiderite  by  tlie  phofphorick  acid. 

The  effe£t  of  the  tempering  of  Iron  hkewife  deferves  the  at- 
tention of  the  chemift.  I  am  of  opinion  that  the  hardnefs  and 
brilliancy  which  iron  acquires  by  this  operation,  arifes  from  its 
integrant  parts,  which  are  feparated  by  the  hear,  being  kept  and 
left  at  a  certain  diflance  from  each  other  by  the  fudden  cold^ 
which  drives  out  the  heat,  without  bringing  the  conftituent  prin- 
ciples of  the  mafs  together.  The  iron  is  then  more  brittle,  be- 
caufe  the  affinity  of  aggregation  is  lefs. 

Iron  is  eafily  oxided.  A  bar  of  iron  which  is  heated  a  long 
time  in  the  foige  furnace,  becomes  oxided  at  its  furface  5  and 
the  coatings  of  metal  which  pafs  to  the  ftate  of  oxide,  are  fepa- 
rated from  the  mafs  in  the  form  of  fcales.  The  moft  degraded 
and  the  moft  altered  metal,  in  the  ftate  when  it  is  no  longer  at- 
tracted by  the  magnet,  forms  an  oxide  of  a  reddlfh  brown  col- 
our, known  by  the  name  of  Aftringent  Saffron  of  Mars,  or  the 
Brown  Oxide  of  Iron. 

The  colour  of  this  oxide  varies  according  to  its  degree  of  ox- 
idation. It  is  yellow,  poppy-colour,  or  red  •,  and  is  eafily  re- 
duced into  a  black  powder,  when  heated  with  coaly  matters. 

The  combined  action  of  air  and  water  conftitutes  a  martial 
oxide,  known  by  the  name  of  Aperitive  Saffron  of  Mars.  This 
compofition  is  produced  by  the  combination  of  oxigenous  gas 
and  carbonlck  gas  with  the  iron.  The  expofition  of  the  iron  to 
a  humid  atmofphere  rufts  it  fpeedily,  and  caufes  it  to  pafs  to  the 
ftate  of  aperitive  faffron  of  Mars.  This  preparation  is  a  true 
carbonate  of  Iron. 

Water  likewife  aOs  upon  iron.  If  Iron  filings  be  put  into 
this  liquid,  and  be  agitated  from  time  to  time,  the  iron  becomes 
divided,  and  blackens  •,  and  by  decanting  the  turbid  M'ater,  a 
black  powder  is  depofited,  which  is  called  the  Martial  -ZEthiops 
of  Lemery  or  the  Black  Oxide  of  Iron.  It  is  a  commencement  of 
calcination  effected  by  the  air  contained  In  the  water  ;  but  more 
efpeclally  by  the  decompofitlon  of  the  water  itfeli. 

The  fixed  and  volatile  alkalis,  in  the  fluid  ftate,  being  digefted 
upon  iron,  oxide  a  flight  portion,  y/hich  falls  down  in  the  form 
of  xthiops. 

All  acids  a6l  more  or  lefs  upon  iron. 

1.  The  concentrated  fulphurick  acid  is  decornpofed  by  boil- 
ing upon  this  metal.     If  the  mixture  be  diftiJIed  to  drynef:^,  tJ  e 


Habitudes  of  Iron.  34^ 

retort  is  found  to  contain  fublimed  fulphur,  and  a  white  mafs, 
partly  foliible  in  v/ater,  but  incapable  of  cryllallization. 

But  if  the  diluted  fulphurick  acid  be  poured  upon  iron,  a  ccn- 
fiderable  eiFervefcence  arifes  in  confequence  of  the  difengage- 
ment  of  hydrogenous  gas.  In  this  operation,  the  water  is  de- 
compofed,  its  oxigenc  is  employed  to  calcine  the  metal,  while 
the  hydrogene  is  difengaged  j  and  the  acid  a£ts  upon  and  dif- 
folves  the  metal  without  being  decompofcd.  This  folution, 
when  concentrated  by  evaporation,  afFbrds  the  fulphate  of  iron, 
which  we  have  already  treated  of. 

2.  The  nitrick  acid  is  decompofcd  rapidly  upon  iron.  The 
folution  is  of  a  red  brown  colour,  and  fuffers  the  oxide  of  iron 
to  fall  down  at  the  expiration  of  a  certain  time.  If  new  iron 
be  plunged  in  this  folution,  the  acid  difiblves  it,  and  lets  fall  the 
oxide  which  it  held  in  folution. 

If  the  folutions  be  concentrated,  martial  ochre  of  a  red  brown 
colour  falls  down.  If  the  concentration  be  carried  ftill  further, 
A  reddifli  jelly  is  formed,  which  is  partially  foluble  in  water. 

Iron  precipitated  from  its  folution  by  the  carbonate  of  pot- 
afti,  is  eafily  diflblved  by  the  fuperabundant  alkali,  and  forms 
the  martial  alkaline  tinfture  of  Stahl. 

Mr.  Maret  has  propofed  to  precipitate  the  iron  by  the  cauf- 
tick  alkali,  to  make  the  sethiops  immediately.  Mr.  Darcet,  in 
•  rendering  an  account  of  the  procefs  of  Mr.  Maret  to  the  Royal 
Society  of  medicine,  has  propofed  that  of  Mr.  Crohare,  which 
confifls  in  boiling  upon  the  iron  water  acidulated  with  the  mu- 
riatick  acid. 

Mr.  De  Fourcroy  made  a  courfe  of  experiments  upon  the 
martial  precipitates,  which  throws  much  light  upon  the  caufes 
of  the  alloniihing  varieties  obferved  in  them.  He  has  proved 
that  the  whole  depends  either  on  ih.c  nature  of  the  acid,  or  the 
manner  of  operating  at  the  time  of  making  thefe  precipitates;  or 
the  quality  of  the  precipitant. 

3.  The  diluted  muriatick  acid  attacks  iron  with  vehemence. 
Hytlrogcnous  gas  is  difengaged,  which  arifes  from  the  decompc- 
fition  of  the  water.  If  the  folution  be  concentrated,  and  left  to 
cool  when  it  is  of  the  thicknefs  of  fyrup,  a  magma  is  formed  ; 
thin,  flattened  cryflalsare  perceived,  which  are  very  deliquefcent. 
The  muriate  of  iron,  diftilled  in  a  retort  by  the  Duke  D'Ayen, 
exhibited  very  fingular  phenomena.  The  firil  produ(5l  was  an 
acid  phlegm.  At  a  ftronger  heat,  a  non-dcliquefcent  muriate 
of  iron  fublimed,  at  the  fame  time  that  very  tranfparent  cryllals 
rofe  to  the  roof  of  the  retort,  in  the  form  of  the  blndes  of  razors, 
which  decompofcd  tl^.e  light  in  the  fiuiie  manner  as  the  beft 
prifms.     At  the  bottom  of  the  retort  there  remained  a  (typtick 


35^  For  motion  of  InL 

deliquefcent  fait,  of  a  brilliant  colour,  and  a  foliated  appearance, 
which  exactly  refeiVibled  the  large  plated  talc,  improperly  called 
Mufcovy  Glafs.  This  lafl  fait  expofed  to  a  violent  heat,  afford- 
ed a  fublimate  more  aflonlfhing  than  the  former  produdls.  It 
was  an  opaque  fubftance,  truly  mctallick,  which  exhibited  fec- 
tions  of  hcxahedral  prifms,  polifhed  like  fteel.  It  was  iron  re- 
duced, and  fublimed. 

4.  It  was  long  fmce  knov,  n  that  iron  is  precipitated  from  its 
folutions  by  vegetable  adringent  fubftances  -,  and  the  black  dyes, 
and  the  fabrication  of  ink,  are  founded  on  this  known  fa*^:. 
But  it  was  not  till  lately  tliat  an  acid  has  been  proved  to  exift  in 
thefe  ful) fiances,  which  combined  with  the  iron,  and  which  may 
be  obtained  from  all  thefe  aftringent  vegetables,  either  by  fimple 
diftiilation,  or  by  mere  digellion  in  cold  water.  The  mod  fim- 
ple procefs  is  the  folJowing  :    . 

Infufe  one  pound  of  powder  of  nut-galls  in  2^  pints  of  pure 
water.  Leave  the  mixture  together  for  four  days,  frequently 
ihaking  the  infufion.  Then  filter,  and  leave  the  fluid  in  a  veflel 
fimply  covered  with  blotting  paper.  The  liquid  becomes  cover- 
ed with  a  thick  pellicle  of  mouldinefs,  and  a  precipitate  falls 
down  in  proportion  as  the  infuflon  evaporates.  Thefe  precipi- 
tates collected,  and  diflblved  in  boiling  water,  form  a  liquor  of 
a  brown  yellow  colour,  which,  evaporated  by  a  gentle  hqat,  de- 
pofites — I.  A  precipitate  which  refembles  fine  fand.  2.  Cryftals 
difpoied  in  the  form  of  a  ftar.  This  fait  is  grey  ;  and  it  is  im- 
polfible  to  obtain  it  of  a  whiter  colour  by  any  repetition  of  fo- 
lutions and  cryflallizations. 

It  is  an  acid  which  effervefces  with  chalk,  and  reddens  the 
infufion  of  turnfole. 

Half  an  ounce  of  this  fait  is  foluble  in  an  ounce  and  an  half 
of  boiling  water,  or  twelve  ounces  of  cold  water. 

Boiling  fpirit  of  wine  dilTolves  its  own  weight  of  this  acid ; 
but  cold  fpirit  diflblves  only  one  fourth. 

This  fait  is  inflammable  in  the  fire.  It  melts,  and  leaves  a 
coal  of  difficult  incineraiion. 

When  this  acid  is  diftilled  in  a  retort,  it  becomes  at  firfl  fluid, 
gives  out  an  acid  phlegm,  but  no  oil  ;  and,  towards  the  end,  a 
white  fublimate  riles,  which  attaches  itfelf  to  the  neck  of  the 
retort,  and  remains  fluid  as  long  as  it  is  hot,  but  afterwards 
cryftallizes.  Much  coal  is  found  in  the  retort.  The  fublimate 
has  nearly  tl  e  tafte  and  fmell  of  acid  of  benzoin,  is  as  foluble 
in  water  as  in  fpirit  of  wine,  reddens  the  infufion  of  turnfole,, 
and  precipitJitcs  mctallick  folutions  with  their  different  colours., 
antl  iron  bl;;ck. 


Dif cover y  of  Ptujfian  Blue.  ^Pl 

The  folution  of  the  fait  of  the  nut-gall,  poured  into  a  folatioii 
of  ^old,  renders  it  of  a  dark  green  \  and  precipitates  a  brown 
powder,  which  is  gold  revived. 

The  iblution  of  filver  becomes  brown  -,  and  at  length  depofites 
a  grey  powder,  which  is  revived  filver. 

The  folution  of  mercury  is  precipitated  of  a  yellow  orange 
colour. 

The  folution  of  copper  affords  a  brown  precipitate. 

The  folution  of  iron  becomes  black 

The  folution  of  the  acetite  of  lead  is  precipitated  white. 

This  fait  is  changed  into  the  oxalick  acid,  if  the  nitrick  2.Z1A 
be  diftilled  from  it. 

The  bafis  of  ink  confifts  of  a  folution  of  iron  by  the  gallick 
acid.  To  make  good  ink,  take  one  pound  of  nut-galls,  fix 
ounces  of  gum  arabick,  and  fix  ounces  of  green  copperas,  with 
four  pints  of  common  water.  The  nut-galls  mud  be  bruifed, 
and  infufed  for  four  hours  without  boiling.  The  pounded  giira 
muftbe  firft  added,  and  fufFered  to  diflblve  ;  and  lallly,  the  cop- 
peras, which  immediately  converts  the  fluid  to  a  black  colour. 
Lewis,  of  the  Royal  Society  of  London,  made  many  refearches 
on  this  fubje£l ;  but  he  always  returns  to  the  forementioned 
fubftances.  Powdered  fugar  is  fometimes  added,  to  render  the 
ink  fhining. 

5.  The  vegetable  acid  like  wife  diflblves  iron  with  facility. 
It  is  this  which  holds  the  metal  fufpended  in  vegetables  ;  and 
it  may  be  precipitated  from  wine  in  the  form  of  sethiops,  by  the 
means  of  alkalis. 

6.  Cream  of  tartar,  or  the  acidulous  tartrite  of  pot-afli,  likewifc 
difTolves  iron  ;  and  the  various  degrees  of  concentration  of  thi^ 
folution  forms  the  foluble  martial  tartiir,  the  aperitive  extradl  ot 
Mars,  and  the  balls  of  Nancy. 

7.  The  folution  of  iron,  by  the  oxalick  acid,  affords  prifmat- 
ick  cryftals  of  agreeniih  yellow  colour,  and  a  fomewhat  aftrin- 
gent  tafte,  foluble  in  water,  and  efHorefcinL,^  by  heat. 

8.  Iron  difiblved  by  the  pruflick  acid,  forms  PrufTian  blue,  or 
the  prulliate  of  iron. 

A  fingular  miilake  gave  rife  to  the  difcovery  of  this  fubibince. 
Diefbach,  achemift  of  Berlin,  being  dtffirous  of  precipitating  a 
decoifHon  of  cochineal  with  fixed  alkali,  borrowed  of  Dippel  an 
alkali  upon  which  he  had  feveral  times  diftilled  animal  o'rl  ;  and 
as  the  deco(ftion  of  the  cochineal  contained  fulphate  of  iron,  the 
liquor  immediately  alTbrded  a  beautiful  blue.  The  experiment 
being  repeated  was  followed  with  fimiUrrefults  ;  and  this  col- 
our became  an  object:  of  comniercc^  under  ti.e  name  of  Prufrnn 
Blue. 


3^2  Theory  of  FruJ/ian  Blue. 

Pruflian  blue  was  announced  in  the  Memoirs  of  the  Acade- 
my of  Berlin  in  the  year  1 7  ro,  but  without  any  account  of  the 
procefs,  which  was  kept  a  fecret  until  other  chemifls  difovered 
it.  The  procefs  was  rendered  pubhck  in  the  year  1724,  in  the 
Phllofophical  Tranfa£i:ions,  by  Woodward  ;  who  declared  that 
he  had  received  it  from  one  of  his  friends  in  Germany. 

To  make  Pruflian  blue,  four  ounces  of  alkali  are  mixed  with 
the  fame  weight  of  dried  bullocks  blood,  and  the  mixture  expo- 
fed  in  a  crucible,  which  is  covered  in  order  to  (lifle  the  flame  ; 
the  fire  is  kept  up  until  the  mixture  is  converted  into  a  red-hot 
coal-  This  charcoal  is  thrown  into  water  which  is  afterwards 
filtered,  and  concentrated  by  evaporation.  The  hquor  is  known 
by  the  name  of  the  Phlogifticated  Alkali.  On  the  other  hand, 
two  ounces  ofthefulphate  of  iron,  andfourouncesof  the  fulphate 
of  alumine  are  diflblved  in  a  pint  of  water.  The  two  folutions 
are  mixed  and  a  blulfh  depofition  falls  down,  which  is  rendered 
ftill  more  intenfely  blue  by  wafliing  it  with  muriatick  acid. 

Such  is  the  procefs  ufed  in  cheniical  laboratories  ;  but  in 
the  works  in  the  large  way  another  method  is  followed.  E- 
qual  parts  of  the  rafpings  of  horns,  clippings  of  flcins,  or  other 
animal  fubfl:ances,  are  taken  and  converted  into  charcoal.  Ten 
pounds  of  this  coal  are  mixed  with  thirty  pounds  of  pot-afh, 
and  the  mixture  is  calcined  in  an  iron  vefl^el.  After  twelve 
hours  ignition,  the  mixture  acquires  the  form  of  a  foft  pafte, 
which  is  poured  out  into  veflels  of  water.  The  water  is  then 
filtered  ;  and  the  folution  mixed  with  another,  confiding  of 
three  parts  of  alum,  and  one  the  fulphate  of  iron. 

I  have  likewife  made  Pruflian  blue  by  calcining  and  burning 
in  the  fame  vefl^el  equal  parts  of  the  (havings  of  horns  and  tar- 
tar. I  received  the  animal  oil  and  the  ammoniack,  afforded  by 
the  calcination  of  thefe  fubft:ances  in  large  caflcs,  which  commu- 
nicated with  each  other,  and  formed  an  apparatus  after  the  man- 
ner of  Woulfe. 

It  has  likewife  been  obferved  that  the  tips  of  the  thyme,  the 
fun-flower,  and  feveral  other  vegetable  fubfl:ances,  when  treated 
with  alkali,  communicate  to  it  in  a  certain  degree,  the  property 
of  precipitating  iron  of  a  blue  colour. 

Much  reafoniiig  hns  t^en  exhibited  on  the  etiology  of  this 
phenomenon.  Mefli's.  Brown  and  Geoflroy  confidered  Prufli- 
an blue  as  the  phlo^lflon  of  iron,  developed  in  the  lixivium  of 
blood.  The  abbe  Mcnon  imagined  that  the  colour  of  iron  was 
blue,  and  that  the  phloglfticated  alkali  precipitated  it  in  its  nat- 
ural colour. 

Mr.  Macqucr  refuted  the  opinion  of  his  predecefibrs  in  tlie 
year  1752  j  and  propofed  a  fyftem,  in  v/hich  he  considers  Pruf- 


Anal\fis  of  Frujfian  Blue.  ^C^ 

(lan  blue  as  iron  fuperf^iturated  with  phlogifton.  This  (kil- 
ful  chemift  proved  that  the  blue  is  not  foluble  in  any  refpe£l 
in  acids;  and  that  the  alkalis  are  capable  of  diflblving  the  colour- 
ing matter  of  the  PrufTian  blue,  and  of  becoming  faturated  with 
it  to  fuch  a  degree  as  to  be  no  longer  capable  of  efFervefcing. 

Mr.  Sage  affirmed  that  the  iron  was  faturated  with  the  phof- 
phorick  acid  ;  and  the  celebrated  Bergmann  Hkewife  fufpedted 
the  exiftence  of  fome  animal  acid,  as  is  proved  by  his  notes  on 
the  leflbns  of  chetniilry  of  SchetFer.  But  it  was  referved  to  the 
celebrated  Scheele  to  convert  thefe  fufpicions  into  certainty. 

He  has  proved  that  the  lixivium  of  blood,  expofed  for  a  cer- 
tain time  to  the  air,  lofes  the  property  of  precipitating  iron  of  a 
blue  colour  ;  and  he  has  (hewn  that  this  circumftance  depends 
on  the  carbonick  acid  of  the  atmofphere,  which  difengages  the 
colouring  part.  By  adding  a  fmall  quantity  of  fulphate  of  iron 
to  this  lixivium,  it  is  no  longer  changed  in  confequence  of  its  re- 
maining in  the  carboniek  acid.  By  boiling  this  lixivium  upon 
an  oxide  of  iron,  it  is  Hkewife  no  longer  capable  of  change  in 
the  carbonick  acid.  The  iron  has  therefore  the  property  of 
fixing  and  retaining  the  colouring  principle  j  but  it  is  neceflary 
that  it  (liould  not  be  in  the  ftate  of  oxide. 

PrufTian  blue,  treated  in  the  way  of  diftillation  with  the  ful- 
phurick  acid,  permits  a  fluid  to  efcape  that  holds  the  pruffick 
acid  in  folution,  which  may  be  precipitated  upon  iron. 

The  procefles  of  Scheele,\to   obtain  this  acid  in  a  ftate  of  pu- 
rity, confift  in  putting  two  ounces  of   pulverized  Pruffian  blue 
into  a  glafs  cucurbit,  with  one  ounce  of  red  precipitate,  and  ^ly^ 
ounces  of  water.     This  mixture  is  to  be  boiled  for  fome  min- 
utes, continually  ftirring  it.     It  then  afiumes  a  yellow  colour  in- 
clining to  green.      Fhe  fluid  being  filtered,   two  ounces  of  boil- 
ing water   are  to  be  thrown  on  the  refidue.      This   liquor  is  a 
prufliate  of  mercury,    which  cannot  be  decompofed  either  by 
alkahs  or  acids.     The  folution  is  then  poured  into  a  bottle,  in 
which  an  ounce  of  newly-made   filings  of  iron  is  put :    three 
gros  of  concentrated  fulphurick  acid  are  to  be  added,  and  the 
whole  agitated  ftrongly  for  fevetal  minutes.      The  mixture  be- 
comes perfedlly  black  by  the  redu£lion  of  the  mercury  ;  the  li- 
quor lofes  its  mercurial  tafte  and  exhibits  that  of  the  colourintr 
lixivium.     After  fufFering  it  to  ftand  at  reft  for  a  time,  it  is  de- 
canted, put  into  a  retort,   and  diftilled   by  a  gentle   fire.       The 
colouring  principle  pafles  firit,  becaufe  more  volatile  than  water. 
The  operation  muft  be  put  an  end  to,  as  foon  as  one  quarter  of 
the  liquor  has  pafled  over.       As  this  produdl   contains  a  fmall 
quantity  of  fulphurick  acid,  it  may  be  cleared  of  it  by  re-diftil- 
y^A^^   it  from   pulverized  chalk   by  a  very  gentle  fire.       The 
2..W 


^54  .Attaints  of  Prujftan-  Acid, 

pruffick  acid  then  comes  over  in  a  ftate  of  the  greatefl:  puritv^ 
Scheele  recommencis  that  the  vefTels  be  well  luted,  becaufe  the 
acid  would  othervvife  efcape  on  account  of  its  great  levity.  It 
is  even  of  advantage  to  put  a  fmall  quantity  of  water  into  the 
receivers,  to  abforb  the  acid  j  and  it  would  like  wife  be  very  pro- 
per to  furround  them  with  pounded  ice. 

This  acid  has  a  particular  fmell  which  is  not  difagreeable  ; 
and  its  tafte  is  fweet. 

It  does  not  redden  blue  paper  ;  but  renders  the  folutions  of 
foap  and  of  the  fulphure  of  alkali  turbid.  Mr.  Weftrumb  pre- 
tends that  the  pruffick  acid  is  the  fame  as  the  phofphorick  ;  for  he 
obtained  fiderite  from  Pruffian  blue,  and  formed  animal  earth  by 
mixing  the  lixivium  of  blood  with  a  folution  of  calcareous  earth. 

The  folution  of  iron  in  the  pruffick  acid  affords  Pruffian  blue. 
We  are  indebted  to  Mr.  Berthollet  for  a  very  interefting  feries 
of  experiments  upon  the  pruffick  acid,  and  its  combinations. 

The  oxide  of  iron  is  capable  of  exifting  in  two  different  ftates 
in  combination  with  the  pruffick  acid.  If  the  oxide  predomi- 
nates, the  combination  is  yeliowiffi  ;  but  if  its  proportion  belefs, 
the  produ£l  is  Pruffian  blue.  All  the  acids  are  capable  of  dif- 
folving  the  portion  or  furplus  of  oxide  which  conftitutes  the 
difference  between  the  firft  and  fecond  combination. 

The  pruffiate  of  pot-aOi  contains  oxide  of  iron.  If  an  acid 
be  poured  in,  this  oxide  is  diffolved,  and  is  precipitated  by  dou- 
ble affinity  in  the  form  of  Pruffian  blue.  ,  The  pruffiate  of  pot- 
afh  made  by  a  gentle  heat,  afterwards  evaporated  to  drynefs, 
then  re-diiTolved  and  filtered,  no  longer  affords  the  blue  upon 
the  addition  of  acids.  It  cryftallizes  in  fquare  plates  with  their 
edges  cut  flantways,  forming  ocflahedrons,  whofe  two  oppofite 
pyramids  are  truncated.  This  folution  of  the  pruffiate  of  pot- 
sfli,  when^  mixed  with  the  fulphurick  acid,.depofites  Pruffian 
blue,  if  it  be  expofed  to  the  folar  light,  or  to  a  ftrong  heat.  In 
thefe  procefles  the  pruffiate  of  alkali  may  be  entirely  decompof- 
cd  ;  the  pruffiate  of  iron  when  precipitated  by  the  action  of  the 
alkaline  pruffiate^  carries  down  with  it  a  notable  proportion  of 
alkali,  of  which  it  may  be  cleared  by  wafhings,  which  contain- 
the  alkaline  pruffiate.  It  is  the  fame  with  regard  to  precipita- 
tions by  the  pruffiates  of  lime  and  ammoniack. 

The  pruffiate  of  mercury  cryllallizes  in  tretahedral  prifms,. 
terminating  in  quadrangular  pyramids,  v/hofe  planes  anfwer  to' 
the  angles  of  the  prifms.  Iron  in  its  metallick  (late  decompo- 
fes  the  pruffiate  of  mercury,  and  deprives  it  both  of  its  oxigene' 
and  its  acid.  The  oxide  of  mercury  likewife  decompofes  the 
pruffiate  of  iron  and  feizes  its  acid.  The  pruffiate  of  mercury 
ia  but  imperfe<5lly  decompofed  by  the  fulphurick  and  muriaticE 


Analyfis  of  Fruffian  Acid,  355 

.^cids.  Thefe  acids  form  trifules,  or  triple  falts  with  it.  The 
precipitate  of  the  nitrate  of  barytes  by  the  pruihck  acid,  is  not 
the  compound  which  Bergmann  fuppbfed  it  to  be,  but  is  mere- 
Jy  a  trifule. 

The  pruflick  acid  readily  precipitates  alumine  from  its  nitrick 
folution  ;  the  alumine  neverthelefs  yields  its  pruihck  acid  to 
iron. 

The  oxigenated  jnuriatick  acid,  when  mixed  with  the  pruflick 
acid,  is  again  converted  to  the  ftate  of  common  muriarick  acid  : 
the  prufTick  acid  afTumes  a  more  lively  fmell,  becomes  more  vol- 
atile, is  deprived  of  its  affinity  to  alkalis  and  lime  ;  it  precipi- 
tates iron  of  a  green  colour  ;  and  the  green  becomes  blue  if  the 
precipitates  be  expofed  to  light,  or  if  it  be  treated  with  the  ful- 
phureous  acid. 

The  pruffick  acid,  impregnated  with  the  oxigenated  muriat* 
ick  acid,  and  expofed  to  light,  aflumes  the  fmell  of  an  aromat- 
ick  oil,  is  colledled  at  the  bottom  of  the  water  in  the  form  of  an 
oil  which  is  not  inflammable,  and  rifes  in  vapour  by  a  gentle 
heat.  By  repeating  this  procefs  it  may  be  totally  decompofed  ; 
and  then  this  fpecies  of  oil  becomes  concrete,  and  is  reduced  in- 
to cryftals. 

The  acid  appears  to  have  undergone  a  partial  combuftion  in 
this  operation  ;  at  lead  the  light  and  the  fulphureous  acid  do 
not  reftore  it  but  by  depriving  it  of  oxigene.  The  oxigenated 
pruffick  acid,  mixed  with  lime  or  a  fixed  alkali,  becomes  totally 
decompofed.  Volatile  alkali  is  difengaged  ;  and  if  the  alkali 
was  very  cauftick,  fuch  as  the  alcohol  of  pot-afh,  it  becomes  ef- 
fervefcent. 

The  pruffick  acid  of  Scheele  is  only  decompofed  in  part  by 
this  procefs  j  whence  Mr.  Berthollet  concludes  that  it  is  com- 
pofed  of  hydrogene,  nitrogene,  and  carbone. 

Thefe  experiments  do  not  prove  that  oxigene  exifts  in  this 
acid.  The  water  affi^rds  that  which  enters  into  the  carbonick 
acid,  produced  by  the  diflillation  of  the  pruffick  acid.  Pruffian 
blue  takes  fire  more  eafily  than  fulphur,  and  detonates  ftrongly 
with  the  oxigenated  muriate  of  pot-afh.  The  prulRate  of  mer- 
cury detonates  ftill  mere  ftrongly  with  the  nitrate  of  mercury. 
The  gas  of  thefe  detonations  has  not  yet  been  collected.  The 
pruffick  acid,  combined  with  alkali  and  the  oxide  of  iron,  cannot 
be  feparated  by  any  acid  without  intervention  of  heat  or  light  ; 
and  when  it  is  difengaged,  it  is  no  longer  capable  of  feparating 
iron  from  the  weakelt  acid,  unlefs  it  be  in  the  way  of  double 
affinity.  Mr.  Berthollet  thinks  that  the  elaftick  ftate  of  this 
acid  diminiffies  this  affinity  ;  and  that  it  is  neceffiiry,  in  order 
xhat  it  may  eafily  enter  into  combination,  that  it  fliould  have  lol^ 


35^  HahtUtdes  of  Iron, 

fome  of  its  fpeclfick  heat.     It  is  this  which  renderg  the  oxigOr 
nated  acid  fo  feeble. 

Pruffian  blue  afforded  me,  by  diftillation,  in  the  ounce,  one 
gros  twenty-four  grains  of  ammoniack,  thirty-fix  grains  of  the 
carbonate  of  ammoniack,  four  gros  twelve  grains  of  oxide  of  iron » 
or  alumine,  and  one  hundred  and  fixty-four  inches  of  hydrogen- 
ous gas  burning  with  a  blue  flame. 

The  ammoniack  comes  over  in  combination  with  a  fmali 
quantity  of  the  colouring  principle,  which  it  takes  up,  and  holds. 
in  folution  :  the  fulphurick  acid  renders  this  vifible. 

Ammoniack  heated  upon  Pruflianblue  decompofesit,by  feiz- 
ing  the  colouring  matter. 

Lime-water  digefted  upon  Pruffian  blue  diflblves  the  colour- 
ing principle  by  the  affiftance  of  a  gentle  heat  ;  the  combination 
is  rapid,  and  the  water  acquires  a  yellow  colour.  By  filtration > 
the  liquor  pafles  of  a  fine  bright  yellow,  no  longer  converts  fyr- 
up  of  violets  to  a  green,  and  is  no  longer  precipitated  by  the  car- 
bonick  acid.  It  appears  to  be  completely  neutralized,  and  af- 
fords an  exceedingly  fine  blue,  when  poured  into  a  folution  of 
the  fulphate  of  iron.  The  prulFiate  of  lime  has  been  propofedj 
by  Meflrs.  Fourcroy  and  Schcele,  as  the  moft  accurate  means  of 
afcertaining  the  pre  fence  of  iron  in  any  mineral  water. 

The  pure  fixed  alkalis  immediately  difcolour  Pruffian  blue  in 
the  cold.  This  combination  produces  heat  j  and  the  pure  alka- 
lis ought  to  be  preferred  to  the  carbonates  of  alkali  in  experi-. 
ments  of  this  nature. 

Magnefia  like  wife  feizes  the  colouring  matter  of  Prufiiar^ 
blue  ;  but  much  more  weakly  than  lime-water. 

A  mixture  of  equal  parts  of  fteel  filings  and  nitrate  of  pot-afh, 
thrown  into  a  crucible  ftrongly  ignited,  detonates  at  the  end  of 
a  certain  time,  with  the  difengagement  of  a  coniidcrable  quan- 
tity of  very  bright  fparks.  The  refidue,  when  wafiied  and  fil- 
tered, affords  an  oxide  of  iron  of  a  yellowifli  colour,  known  by 
the  name  of  Zwelfer's  Saffron  of  Mars. 

Iron  decompofes  the  muriate  of  ammoniack  very  well.  Two 
gros  of  fleel  filings,  and  one  gros  of  this  fait,  afforded  Mr,  Buc- 
quet,  by  diftillation  in  the  pneumato-chemical  apparatus  over 
mercury,  fifty-four  cubick  inches  of  an  aeriform  fluid  ;  half  of 
which  was  alkaline  gas,  and  the  other  half  hydrogenous  gas. 

This  decompofition  is  founded  on  the  flrong  aQion  of  the 
muriatick  acid  of  iron. 

One  pound  of  the  muriate  of  ammoniack  in  powder,  and  one 
ounce  of  fteel  filings,  fublimed  together,  form  the  Martial  flow- 
ers, or  Ens  Martis.  Thefe  flowers  confift  merely  of  the  muri- 
ate of  ammoniack,  coloured,  and  rendered  yellow  by  an  oxide 
of  iron. 


Tin  Plates.      Ujh  cf  Ifon»  357 

The  oxide  of  iron  decompofes  the  muTiate  of  ammoniack 
much  better.  This  is  an  effedt  of  double  allinity.  The  am- 
moniack which  rifes  is  fometimes  effervefcent. 

A  rnixture  of  good  filings  of  fleel  and  fulphur,  moiftene'd 
•with  a  fmail  quantity  of  water,  becomes  heated  in  the  courfe  of 
feveral  hours.  The  water  is  decompofed,  the  iron  rufts,  the 
fulphur  is  converted  into  acid,  the  hydrogenous  gas  of  the  wa- 
ter exhales,  and  the  heat  is  fometimes  fufficient  to  fet  the  mixture 
pn   fire.     This  phenomenon  conilitutesiJie  volcano  of  Lemery, 

There  is  the  ftronged  analogy  both  in  the  phenomena  and 
efiedls  of  the  inflammation  of  this  volcano,  and  the  decompofi- 
tion  of  pyrites. 

Sulphur  combines  eafily  viith  iron  by  fuuon,  and  then  forms 
a  true  martial  pyrites. 

Iron  may  be  alloyed  with'  feveral  metallick  fubftances  *,  but 
the  only  alloy  which  is  ufed  in  the  arts  is  that  which  it  contra<Sts 
with  tin,  to  form  white  iron,  or  tin  plates. 

To  fcrm  tin  plates  (commonly  known  by  the  name  of  Tin  in 
England)  the  fofteft  iron  is  chofen,  which  is  reduced  into  very- 
thin  plates.  Care  is  taken  to  polifli  or  clean  the  furface  very 
well ;  and  this  is  done  in  feveral  ways.  The  pieces  are  rub-» 
bed  with  fand-flone,  and  afterwards  kept  for  three  times  twenty- 
four  hours  in  Vt'ater,  acidulated  by  the  fermentation  of  malt, 
turning  them  from  time  to  time.  They  are  afterwards  cleaned, 
dried,  and  are  then  ready  for  tinning.  Sal  ammoniack  is  like- 
wife  ufed  in  fome  rnanufaifbories.  For  this  purpofe  the  plates 
are  difpofed  in  a  chamber,  in  which  a  certain  quantity  of  fal 
ammoniack  is  volatilized.  The  fait  forms  a  covering  over  the 
whole  furface  of  every  plate,  and  pOilefTe^  the  double  advant- 
age of  clearing  it  from  ruft,  and  afFordin|  tlie  coaly  principle 
necefl'ary  to  prevent  the  calcination  of  the  metal. 

When  the  iron  is  well  cleared,  the  plates  are  plunged  verti-! 
cally  into  a  bath  of  tin,  whofe  furface  is  covered  with  pitch  or 
tallow.  They  are  turned  in  the  bath ;  and  when  taken  out, 
they  are  wiped  vvitii  faw-dull  or  bran. 

The  ufes  of  'iron  are  fo  very  extenfive,  that  there  are  few 
arts  which  can  be  praclifed  without  it.  It  is  with  juflice  con- 
fidered  as  the  foul  of  all  the  arts.  Some  of  its  ores  are  ufed 
in  their  native  ftate  j  fuch  as  the  haematites,  which  is  niade  in- 
to burnifhers. 

The  fulphate  of  iron  is  the  bafis  of  all  black  colours,  inks,  &c. 

The  ochres  are  ufed  by  painters,  under  the  name  of  Umber  ; 
and  the  brown  red  has  the  moll  extended  ufe.  With  us  (in 
France)  it  is  applied  to  give  a  colour  to  brick  pavements,  to 
paint  our  doors  and  windows,  to  fmear  our  ca/ks,  and  to  fecurc 
^hem  from  decay  and  infeds  in  fea  voyages. 


35'S  Proptrtiis  of  Copper, 

,Caft  iron  is  ufcd  to  make  boilers,  chimney-grates,  hearths,  pots^ 
Zee,  The  inftrumcnts  of  agriculture  are  made  of  this  metal : 
Heel  is  ufed  not  only  as  fteel  \  but  its  hardnefs  renders  it  proper 
to  cut  and  work  the  other  metals. 

The  magncrical  property  of  iron  has  led  to  the  difcovery  of 
, the  mariner's  compafs ;  and  this  metal,  if  it  were  produdive  of 
no  other  advantage  to  mankind,  would  on  that  account  be  en- 
titled to  their  greatefl  attention. 

Pruffian  blue  is  an  agreeable  colour,  greatly  efteemed,  and 
much  ufed. 

Iron  likewife  furni(hes  the  art  of  medicine  with  remedies. 
It  is  the  only  metal  which  is  not  noxious  ;  and  it  has  fuch  an 
analogy  with  our  organs,  that  it  appears  to  conftitute  one  of  the 
-elements  of  the  human  frame-  Its  efFedls  in  general  confill  in 
llrengthening  the  ftomach  j  and  it  appears  to  polTefs  the  proper- 
ty of  paffmg  in  the  circulation  under  the  form  of  sethiops.  The 
valuable  experiments  of  Mr.  Menghini,  publiflied  in  the  Me- 
moirs of  the  Inftitute  of  Bologna,  have  proved  that  the  blood  of 
jjerfons  who  take  martial  remedies  is  thicker,  and  contains  more 
iron.  Mr.  Lorry  obferved  that  the  urine  of  a  fick  perfon,  to 
Vnom  he  adminiftered  iron  in  a  flate  of  extreme  divifion^  was 
manifeftly  coloured  with  the  nut-gall. 


CHAPTER  XL 

Concerning  Copper, 

<I!OPPER  is  a  reddifh  metal,  hard,  elaflick,  fonorous,  an4 
affording  a  difagreeable  fmell  by  fridion.  It  tafte  is  ftyptick, 
and  naufeous.  One  cubick  foot  of  copper  weighs  five  hundred 
:find  forty-five  pounds.  The  fpecifick  gravity  of  caft  copper  not 
iiammered  is  7.7880- — BrifTon, 

The  alchemilts  diftin^uilhed  this  metal  by  the  name  of  Venus, 
on  account  of  the  facility  with  which  it  unites  and  is  alloyed 
with  other  metals. 

It  may  be  reduced  into  very  thin  leaves,  and  drawn  into  very 
fine  wire.  The  tenacity  of  this  metal  is  fuch,  that  a  wire  of  one 
tenth  of  an  inch  in  diameter,  is  capable  of  fupporting  a  weight 
of  two  hundred  and  ninety-nine  pounds  four  ounces,  without 
t)reaking. 

This  metal  is  capable  of  afFe6ling  a  regular  form.  The  abbt! 
Mongez  obferved  it  in  foUd  quadrangular  pyramids,  fometime^ 
infertcd  into  each  other. 


Ores  of  CoppeiP,  35^ 

Copper  is  found  in  various  forms  in  the  bowels  of  the 
earth. 

1.  Native  copper. — This  copper  exifts  fometimcsin  leaves  in 
a  gangue  of  quartz.  It  is  likewife  found  in  compacl  mafTes  at 
Japan.  There  is  one  of  thefe  pieces  in  the  royal  cabinet,  which 
weighs  ten  or  twelve  pounds. 

Native  copper  is  ufually  dilTeminated  in  a  brownifli  martial 
earth,  fufceptlble  of  a  polifh.  When,  this  ore  is  rubbed  with  a 
flint,  the  traces  appear  of  a  beautiful  copper-colour.  Ores  of 
this  kind  are  found  at  Kaumfdorf  in  Thuringia — Sage,  Analyfe 
Chimique,  t.  iii.  p.  205. 

We  have  likewife  found  native  copper  at  Saint  Sauveur.  It 
has  the  form  of  nodules  refembling  ftaladites.  Mod  of  the  na- 
tive coppers  appear  to  be  formed  by  cementation,  or  by  the  pre- 
cipitation of  this  metal  diflblved  in  an  acid,  and  thrown  down 
by  martial  falts. 

Mr.  Sage  thinks  that  this  metal  may  likewife  be  precipitated 
from  its  folutions  by  phofphorus.  To  efFedl,  fays  he,  the  pre- 
cipitation of  copper  by  phofohorus,  twelve  grains  of  this  metal 
are  to  be  diflblved  in  half  a  gros  of  nitrick  acid.  The  folution 
mud  be  poured  into  half  a  pint  of  diftilled  water,  into  which 
a  cylinder  of  phofphorus,  two  inches  long,  weighing  forty-eight 
grains,  muft  be  plunged.  The  furface  becomes  almoft  immedi- 
ately black,  and  is  covered  with  particles  of  copper  pofieffing 
the  metallick  colour  and  brilliancy.  At  the  end  of  feveral  days, 
o£\ahedral  cryflals  are  feen,  whofe  infertions  into  each  other 
produce  elegant  dendrites  ♦,  and  at  the  end  of  ten  days,  the 
twelve  grains  of  copper  are  completely  reduced,  as  is  proved  by- 
pouring  ammoniack  into  the  water.  If  it  do  not  exhibit  a  blue 
colour,  it  is  proof  that  the  ftuid  contains  no  copper. 

2.  Copper  mineralized  by  fulphur  forms  the  yellow  ore  of  cop- 
per. 

This  ore  is  of  a  golden  colour,  and  the  ignorant  are  often 
deceived  by  its  flattering  appearance.  It  contains  a  larger 
quantity  of  copper  in  proportion  as  the  fulphur  is  lefs  in  quan- 
tity, and  gives  fewer  fparks  with  the  fteel.  It  fometimes  cryf- 
tallizes  in  beautiful  octahedrons.  I  pofiefs  two  fpecimens  cov- 
ered over  with  trihedral  pyramids  of  near  an  inch  long,  and  be- 
tween four  and  five  lines  in  diameter  at  the  bafes. 

When  the  fulphur  is  fo  abundant  that  the  proportion  of  cop- 
per will  no  longer  pay  for  the  working,  the  ore  is  called  Macar- 
fire.  T}\e  marcafite  cryftallizes  in  cubes  or  in  oClahedrons,. 
which  eafily  efflorefce. 

The  yellow  copper  ore  is  found  in  various  fl:ates  according  to 
the  courfe  of  its  decompofition.     Tlie  fuft  impreflion  of  hepatick 


360  Ores  cf  Copper. 

vapours  colours  tlie  farface  in  a  thouuind  lliades,  In  which  ftate 
it  is  known  by  the  name  of  Peacocks  Tail,  Pigeons  Neck,  &c. 
The  lad  decree  of  alterntion  of  this  ore,  effected  by  the  fim- 
ple  difengagement  of  fulpliur,  forn^s  the  hepatick  copper  ore. 
The  yellow  colour  is  then  converted  into  an  obfcure  brown  col- 
our :  this  ore  appears  then  to  contain  no  other  principles  but 
■water,  copper,  and  iron,  which  lafl  is  al>^'ays  more  or  lefs  abun- 
dant in  thefe  ores. 

The  yellow  copper  ore  fometimes  forms  fulphate  of  copper 
in  its  decompofitioii.  Tliis  fait  is  diffolved  in  water,  and  forms 
fprings  more  or  lefs  loaded  with  it,  froni  which  the  copper  may 
be  obtained  by  cementation.  Old  iron  is  thrown  into  the  wa- 
ter ;  ^the  copper  is  precipitated,  and  the  iron  takes  its  place.  In 
this  way  it  is  obtained  in  Hungary,  and  we  might  ufe  this  econ- 
omical procefs  in  feveral  parts  of  our  province.  I  have  ftalac- 
tites  in  my  coUeclion,  fent  me  from  Cevennes,  which  are  col- 
oured blue  by  a  very  confiderable  quantity  of  copper.  In  Ge- 
Vaiidan,  at  half  a  quarter  of  a  league  from  St.  Leger  de  Peyre, 
feveral  fprings  of  water  impregnated  with  copper  are  found, 
Mrhich  run  into  a  valley.  The  inhabitants  of  this  canton  drink 
a  glafs  of  the  water  occafionally  as  a  purgative. 

The  llieletons  of  animals  are  fbmetimes  found  in  copper 
mines  penetrated  v^i'ch  that  metal.  Swedenburg  has  given  an 
engraving  of  the  figure  of  a  Ikeleton  of  a  quadruped  taken  out 
of  a  copper-mine  and  coloured  by  that  metal.  In  the  royal  cab- 
inet there  is  a  human  hand,  green  at  the  extremity  of  the  fin- 
gers, the  mufcles  of  which  are  dried  and  greeniih.  According 
to  the  report  of  Mr.  Level,  conful  of  mines,  there  was  found 
at  Falilan  in  Sweden,  in  the  great  copper  mine,  a  human  carcafe, 
which  had  remained  there  forty  years,  with  the  fiefli  and  bones 
entire,  without  corruption,  and  without  emitting  any  fmell. 
The  body  was  clothed  and  entirely  incrufted  with  vitriol.—* 
Atla  Literaria  Suec.  tri.  i.  anno  1722,  p.  250. 

The  turquoife  flones  are  merely  bones  coloured  by  the  oxides 
of  copper.  Mr.  De  Reaumur,  in  the  year  1725,  gave  an  ac- 
count to  the  Academy  of  the  turquoifes  found  in  Lower 
Languedoc.  The  colour  of  the  turquoife  frequently  becomes 
converted  into  green,  which  depends  on  the  alteration  of  the  nie- 
tallick  oxide.  The  turquoife  of  Lower  Languedoc  emits  a  fe- 
tid fmell  by  the  aiflion  of  fire,  and  is  decompofed  by  acids.  The 
turquoife  of  Pruifia  emits  no  fmell,  and  is  not  attacked  by  acids. 
Mr.  Sage  fufpecled  that  the  ofleous  part  is  agitized  in  thefe  Jaft. 
3.  Grey  copper  ore. — The  copper  is  mineralized  by  arfenick. 
It  has  a  grey  colour,  and  an  appearance  nearly  vitreous.  It  ufu- 
ally  coiiUiinb  filver;  and,  when  wrought  to  cxtra(ft  this  precious 


Ores  of  Copper.  361 

metal,  it  is  called  the  Grey  Silver  Ore.  It  affeiTls  a  tetrahedral 
form  ;    and  arfenick  is  the  moft  predominant  of  its  principles. 

4.  The  grey  antimonial  copper  ore. — This  differs  from  the  for- 
mer, becaufe  it  contains  fulphur  and  antimony,  and  is  much 
more  diiiicult  to  be  wrought.  When  expofed  to  the  fire,  it  be- 
comes as  fluid  as  water  ;  the  fulphur  is  volatilized  with  tha  an- 
timony ap,d'  the  arfenick.  The  refidue  of  the  torrefa61ion  is  a 
mixtme  of  the  antimony  and  copper,  and  fometimes  it  contains 
filvcr  likewife. 

5-  Copper  ores,  in  their  decompofitlon,  arereduccd  toa  more 
or  lefs  perfect  Itate  of  oxidation.  The  carbonick  acid  frequent- 
ly unites  to  the  metal,  and  becomes  the  mineralizer.  This  fub- 
ftance  is  known  by  the  name  of  Mountain  Blue,  Azure  of  Cop- 
per, Mountain  Green,  Malachite. 

A.  The  azure  of  copper  cryftallizes  in  rhomboidal  tetrahe- 
dral prifms,  rather  flattened,  terminating  in  dihedral  fummits  : 
thefe  cryftals  are  of  the  moft  beautiful  blue  •,  they  are  frequent- 
ly altered  by  cxpofure  to  the  air,  and  become  converted  into 
malachite. 

Mr.  Sage  has  imitated  the  azure,  both  in  the  form  and  col- 
our, by  difTolving  copper,  in  the  cold,  in  water  faturated  with 
carbonate  of  ammoniack.  When  the  azure  of  copper  is  of  a 
lefs  brilliant  colour,  and  in  the  pulverulent  form,  it  is  called 
Mountain  Blue. 

B.  The  malachite  cryftallized  in  oO:ahedrons  has  been  found 
in  Siberia.  This  ore  is  frequently  ftriated,  formed  into  fmali 
tufts  of  a  filky  appearance,  or  in  very  clofe  parallel  fibres.  The 
malachite  is  frequently  covered  with  protuberances.  This  fig- 
ure appears  to  announce  that  it  has  been  formed  in  the  fame 
manner  as  the  ftala£lites. 

Mountain  green  difl'ers  from  the  malachite  only  in  its  pulve- 
rulent form,  and  the  mixtures  which  alter  it.  The  alterations 
of  the  copper  ores,  and  native  copper  likewife,  produce  a  cupre- 
ous oxide,  which  bears  the  name  of  Red  Copper  Ore.  The 
mine  of  Predanah,  in  the  county  of  Cornwall,  has  afforded  the 
fineft  fpecimens  of  red  copper  ore.  The  metal  is  nearly  in  the 
metalUck  ftate,  and  has  the  form  of  oflahedral  cryftals.  The 
granular  red  copper  ore  differs  from  this  only  in  its  figure.  It 
fometimes  has  a  brown  martial  earth  for  its  gangue. 

The  azure,  the  malachite,  and  the  red  copper  require  no  oth- 
er procefs  but  mere  fufion  with  coal  to  convert  them  into  metal  ; 
the  other  kinds  require  to  be  cleared  of  their  mineralizer  by  tor- 
refa(Elion,  and  afterwards  to  be  fufed  with  three  parts  of  black  flux. 

To  affay  a  fulphureous  copper   ore,  Mr.  Exchaquet  propofes 
to  make  two  gros  of  the  crude  ore,  and  one  of  the  liitrate  of  pot*- 
2...X 


36"2  Worymg  of  Copper  Mines, 

afh  ;  which,  after  pulverization,  are  to  be  detonated  in  an  ignit- 
ed crucible.  The  matter  becomes  hard  after  the  detonation  ;; 
upon  which  the  fire  is  to  be  increafed  and  kept  up,  in  order  that 
the  fulphur  may  be  diflipated.  The  fire  is  then  to  be  ftill  more- 
flrongly  urged,  until  the  ore  enters  into  fufion  ;  and  a  mixture 
of  half  an  ounce  of  tartar,  one  quarter  of  an  ounce  of  fait,  and 
a  fmall  quantity  of  charcoal,  is  to  be  added  in  equal  portions. 
An  effervefcence  takes  place  at  each  projedion  of  the  mixture. 
The  fire  is  then  to  be  dill  more  ftrongly  railed,  and  the  cruci- 
ble covered,  and  kept  in  this  ftate  for  half  an  hour,  in  order 
that  the  copper  may  flow  into  a  mass.  In  this  way  a  very  mal- 
leable button  of  copper  is  obtained. 

The  working  of  copper  ores  varies  according  to  their  com- 
pofition.  But,  as  the  fulphureous  ores  are  moft  commonly 
wrought,  we  ihall  confine  ourfelves  to  the  procefs  which  is  moll 
fuitable  to  their  nature. 

The  metal  is  firll  picked  or  forted  ;  afterwards  pounded  in  a 
mill,  and  wafhed,  to  feparate  the  gangue,  and  other  foreign  fub- 
Itances  ;  it  is  then  roalted  to  drive  ofi^  its  mineralizer ;  and  af- 
terwards fufedin  the  blall  furnace.  The  refult  of  this  firft  fu- 
licn  is  bhck  copper  :  which  is  again  fufed  in  the  refining  fur- 
nace, to  difiipate  all  the  fulphure  which  has  withltood  the  pre- 
ceding operations.  When  it  is  very  pure,  it  is  poured  into  a 
broad  veifel,  or  tell  ;  a  fmall  quantity  of  vi^ater  is  throv/n  on  its  fur- 
face,  which,  being  by  that  means  cooled,  feparat^s  from  the  reft, 
and  is  taken  up.  This  is  the  copper  in  rofettes,  which  is  taken  to 
the  hammer  to  be  beat  into  proper  form.  The  feveral  opera- 
tions are  different  in  various  places.  In  fome  countries,  the  ore 
is  roalled  as  often  as  eight  times  •,  in  others  one  or  two  are  fuf- 
ficient  *,  and  in  fome  places  it  is  not  roafted  at  ail.  This  varie- 
ty depends— I.  On  the  variations  of  pra(5;liGe  :  thofc  who  roaft 
but  little,  employ  more  time  and  care  in  the  fufion  and  refining. 
2.  On  the  nature  of  the  ore  :  when  it  is  rich  in  iron,  the  roatl- 
ings  are  necelTary  to  difpofe  this  metal  to  fufion. 

The  method  of  roafting  is  likewife  prodigioufly  varied.  Pie- 
ces of  the  mineral  are  fometimes  heaped  up  on  a  bed  of  combuf- 
tible  matter,  and  in  this  manner  the  calcination  is  performed  > 
but,  when  this  ore  abounds  with  fulphur,  it  may  be  extradled  by 
the  ingenious  procefs  ufed  at  St.  Bell,  and  defcribed  by  Meflrs. 
Jars  in  their  excellent  work. 

The  fufion  is  commonly  performed  in  the  blaft  furnace  ;  but 
at  Briftol,  in  England,  the  ore  is  roafted  in  a  reverberatory  fur- 
nace,  and  fufed  into  black  copper. 

The  refining  furnace  conflrudled  at  St.  Bell,  by  Meflrs.  Jars, 
apnears  to  me  to  be  one  of  the  beft.      They  have  publifhed  an 


Prcpertks  of  Copper.  363 

^excellent  defcription  of  it,  which  may  be  confulted  in  their  Min- 
eralogical  Travels.  The  refining  of  copper  confifts  in  depriving 
it  of  the  fulphur  and  iron  which  it  may  Itill  retain.  The  fulphur 
is  diflipated  by  fire,  and  bellows  properly  dire(fled ;  and  the 
iron  is  fcorified  by  the  afliftance  of  fome  pounds  of  lead  fuied 
with  the  copper.  The  Ikilful  mineralogilh  whom  I  have  jult 
quoted,  make  ufe  of  a  reverberatory  furnace,  lined  with  char- 
coal ;  and  fufe  and  fkum  their  copper,  without  ufmg  lead. 

When  the  copper  contains  a  fufficient  quantity  of  filver  to  ad- 
mit of  extraftion,  the  following  procefs  is  ufed  : — i.  Seventy- 
five  pounds  of  copper  are  fufed  with  two  hundred  and  feventy- 
five  of  lead.  The  alloy  is  call  into  flat  pieces,  which  are  called 
Loaves  of  Liquation.  2.  Thefe  loaves  are  expofed  to  a  heat 
fufficient  to  fufe  the  lead,  which  carries  the  filver  with  it,  and 
leaves  the  copper,  which  on  account  of  its  being  more  difhcult 
to  fufe,  retains  the  original  form  of  the  loaves ;  and  is  every 
.where  penetrated  by  tlie  interflices  through  which  the  fufed 
metal  made  its  efcape  ;  ihefe  are  called  Dried  Loaves  of  Liqua- 
tion. 3.  They  are  carried  into  a  fecond  furnace,  where  they 
are  expofed  to  a  ftronger  heat,  to  deprive  them  of  the  fmall 
quantity  of  lead  which  they  ftill  retain.  4.  The  lead  is  after- 
wards taken  to  the  cupel,  where  it  is  fufed,  and  feparated  frora 
all  the  filver  it  had  taken  up. 

Copper  is  altered  by  long  expofure  to  the  air.  Its  furface 
becomes  covered  with  a  greenifh  coating,  which  is  very  hard, 
and  known  to  the  antiquarians  under  the  name  of  Patin.  This 
•is  the  feal  which  attefts  the  antiquity  of  flatuss  and  models 
<:overed  with  it. 

Copper,  expofed  to  the  fire,  becomes  blue,  yellow,  and  at 
•iafl  violet.  It  does  not  flow  until  it  is  flrongly  ignited. 
When  in  conta6l  with  the  coals,  it  gives  a  blue  greenifh  tinge 
to  the  flame  .;  and  if  it  be  kept  a  long  time  in  fuSon,  part  of  it 
is  volatilized. 

When  copper  is  heated  in  conta6l  with  air,  it  burns  at  its 
furface,  and  becomes  changed  into  a  blackilh  red  oxide.  This 
oxide  may  be  feparated  by  ftriking  the  plate  which  has  been 
Ignited,  or  by  plunging  it  in  water.  When  the  oxide  has  been 
pounded,  and  moll  flrongly  calcined,  it  afllimes  a  brown  red 
colour,  and  may  be  converted  into  a  glafs  of  a  brown  colour  by 
a  more  violent  heat. 

I.  The  fulphurick  acid  only  a(fls  on  copper  when  concen- 
trated, and  very  hot.  It  then  difTolves  it,  and  eafily  affords  blue 
cryflals  of  a  rhomboidal  form.  The  fulphate  of  copper  is  known 
in  commerce  by  the  name  of  Blue  Vitriol,  Cyprian  VitrioK 
Sliie 'Copper,  &c. 


3^4  Properties  of  Copper* 

Two  methods  are  ufed  to  make  the  fulphate  of  copper  which 
is  met  with  in  commerce.  The  firll  confifts  in  calcining  the 
cupreous  pyrites,  and  caufing  them  to  efliorefce,  in  order  to  de- 
velope  the  lalt,  which  is  then  extra<51ed  by  lixiviation.  The  fe- 
cond  confifts  in  forming  this  pyrites  artificially,  burning  it,  and 
lixiviating  it,  to  extract  the  fait. 

This  fait  pcflelTes  a  very  ftrong  ftyptick  tafte.  It  is  eafily  fu- 
fible  by  heat,  which  diflipates  its  water  of  cryflallization,  and 
changes  its  colour  to  a  bluifli  white.  The  fulphurick  acid  may 
be  extracted  by  a  very  llrong  fire.  Lime  and  magnefia  decom- 
pofe  this  fait  j  and  the  precipitate  is  of  a  bluifti  white  colour. 
If  it  be  dried  in  the  open  air,  it  becomes  green.  Ammoniack 
likewife  precipitates  the  copper  in  3  whitifh  blue  ;  but  the  pre- 
cipitate is  diflblved  nearly  the  fame  inftant  that  it  is  formed  ; 
and  the  refult  is  a  folution  of  a  beautiful  blue  colour,  known  by 
tlie  name  of  Aqua  Celeftis. 

This  fait  contains  in  the  quintal  thirty  pounds  acid,  forty- 
three  water,  and  twenty-feven  copper. 

2.  The  nitrick  acid  attacks  copper  with  efFervefcence,  at  the 
fame  time  that  it  becomes  decompofed,  and  emits  abundance  of 
nitrous  gas.  When  it  is  propofed  to  obtain  this  gas  by  the  ac- 
tion of  the  acid  upon  the  copper,  it  is  necefiary  to  have  the  pre- 
caution of  weakening  the  acid,  and  to  prcfent  the  copper  in 
pieces  of  confiderable  magnitude.  If  thefe  circumftances  be 
not  attended  to,  the  acid  attacks  the  metal  with  fuch  violence, 
as  fuddenly  to  emit  a  prodigious  quantity  (  f  gas  ;  immediately 
after  which  an  abforption  takes  place,  and  the  water  of  the  jar 
palTes  into  the  bottle.  In  this  cafe  ammoniack  is  formed.  The 
diluted  nitrick  acid  perfe6lly  difibives  copper  :  the  folution  is 
blue.  If  it  be  fpeedily  concentrated,  no  other  refult  is  obtained 
but  a  magma  without  cryftals  •,  but  if  it  be  left  expofed  to  the 
air,  it  affords  cryftals  in  long  parallelograms.  By  leaving  a  fo- 
lution of  this  kind  to  fpontaneous  evaporation,  I  have  obtained 
rhomboidal  cryftals,  which,  inftead  of  being  blue,  as  they  are 
■ufually  defcribed,  are  white.  They  decrepitate  upon  the 
coals,  emit  a  red  gas  by  mere  heat,  and  nothing  remains  but  a 
grey  oxide. 

3.  The  muriatick  acid  does  not  dilTolve  copper  unlefs  it  be 
boiling  and  concentrated  ;  the  folution  is  green,  and  affords 
prifmatick  cryftals  of  confiderable  regularity  when  the  evapora- 
tion is  flow.  This  muriate  is  of  an  agreeable  grafs-green  col- 
our ;  its  tafte  is  cauftick,  and  very  aftringent  ;  it  fufes  by  a 
gentle  lieat,  and  congeals  into  a  niafs  ;  in  which  the  acid  is  fo 
adherent,  that  a  very  ftrong  fire  4s  required  to  difengage  it.     It 

,  is  very  deliquefgent.   Ammoniack  docs  not  diflblve  the  oxide  of 


Formaiion  of  Verdigris,  06? 

this  muriate  with  the  fame  facility  as  it  does  that  of  the  other 
cupreous  falts.  This  obfervation  was  made  by  Mr.  De  Four-^ 
croy  ;  which  I  think  may  be  explained  from  the  circum fiance 
that  the  muriaiick  acid  fufFers  the  copper  to  be  precipitated  in 
the  metallick  form,  inltead  of  giving  out  a  portion  of  its  oixgens 
which  would  facilitate  the  action  of  the  alkali. 

4.  The  acetous  acid,  when  made  to  adl  either  hot  or  cold  uo- 
on  copper,  only  corrodes  it,  and  produces  the  fubilance  known 
in  commerce  under  the  name  of  Verdigris.  The  verdigris 
which  is  mod  ufed  in  the  arts  has  been  long  fabricated  at  Mont- 
pellier  exclufiyely.  The  prejudice  which  prevailed,  that  the 
cellars  of  this  city  alone  were  proper  for  this  operation,  prcferv- 
ed  this  commerce  till  lately  in  its  hands.  But  the  progrefs  of 
information  has  fucceliively  put  it  in  the  power  of  other  coun- 
tries to  partake  in  this  manufadture. 

The  procefs  ufed  at  Montpellier  confifts  in  fermenting  the 
refufe  of  grapes  with  four  wine.*  This  refufe  is  afterwards 
Jaid  in  alternate  ftrata,  with  plates  of  copper  fix  inches  long  and 
five  broad.  In  this  flate  tliey  are  left  for  a  certain  time  ;  after 
which  they  are  taken  out,  and  placed  edge  wife  in  a  cellar,  where 
they  are  fprinkled  with  four  wine  :  in  this  fituation  the  verdi- 
gris fwells  up  ;  and  is  afterwards  fcraped  off,  put  into  facks  of 
leather,  and  exported  to  foreign  countries. 

Ready-made  vinegar  is  ufed  at  Grenoble,  and  the  plates  of 
copper  are  fprinkled  with  it. 

The  verdet  or  verdigris  of  Grenoble  contains  one  fixtli  lefs  of 
copper  ;  the  vinegar  which  is  obtained  is  llronger  and  more  a- 
bundant.  It  has  not  the  empyruematick  fm.ell  of  that  of  Mont- 
pellier. The  copper  is  therefore  partly  dlfiblved  in  the  verdet 
of  Grenoble  ;  becaufe  it  has  been  firlt  reduced  into  an  oxide  by 
the  impredion  of  the  vinegar,  and  aflcru'ards  attacked  by  the 
fubfequent  affufion  of  the  fame  acid.  It  is  therefore  an  acetate 
of  copper. 

The  oxides  of  copper,  diifolved  in  vinegar,  form  a  fait  known 
by  the  name  of  Cryltallized  Verdigris,  Cryftals  of  Venus,  Ace- 
tate of  Copper. 

To  obtain  this  fait,  the  vina^Te  or  four  wine  is  diltilled  ;  and 
this  weak  vinegar  boiled  on  the  verdigris.  The  iolution  is  then 
conveyed  into  a  boiler,  where  it  is  concentrated  until  a  pellicle 
appears.  Sticks  are  then  plunged  in  the  bath  ;  and  at  the  ^\\<\. 
of  a  certain  number  of  days  the  Iticks  are  again  taken  out,  cov- 
ered with  rhomboidal  cryllais  of  a  blue  colour.     Xhefe  clufters 

*  Vinafl'e. 


3^5  Habitudes  of  Copper. 

of  cryftals,  weighing  each  from  four  to  fix  pounds,  are  wrapped 
up  in  paper,  and  diftributed  for  fale. 

The  vinegar  may  be  difengaged  by  diflillation  from  thefc 
cryftals  ;  and  the  refidue  is  a  cupreous  oxide,  which  pofTeflea 
the  charadiers  of  pyrophorus. 

Vinegar,  diftilled  on  manganefe,  difiblves  copper  ;  which 
proves  that  it  has  taken  up  oxigene.  Tlie  acetick  acid,  or  rad- 
ical vinegar,  diflers  from  ordinary  vinegar,  in  containing  a  great- 
er quantity  of  oxigene  ;  and  it  is  this  oxigene  which  renders  it 
proper  to  diflbive  copper  in  the  metallick  ftate.  The  acetate  of 
copper  may  likewife  be  formed  by  decompofing  fait  of  Saturn, 
or  fugar  of  lead,  by  the  fulphate  of  copper.  The  fulphatc  of 
lead  falls  down  :  and  the  folution  when  concentrated,  affords^ 
cupreous  acetate. 

5.  The  pure  fixed  alkalis,  digefted  in  the  cold  with  filings  of 
copper,  become  of  a  blue  colour  ;  but  ammoniack  diflblves  it 
much  more  fpeedily.  I  put  copper  filings  into  a  bottle  with 
very  cauftick  ammoniack,  and  kept  the  bottle  flopped  for  two 
years  ;  the  copper  was  deprived  of  its  colour,  and  became  fim- 
ilar  in  appearance  to  a  grey  clay  ;  whereas  a  fimilar  \t^t],  in 
which  I  had  placed  the  fame  mixture,  but  left  open,  foon  afford- 
ed me  very  fmall  blue  cryftals  ;  and  the  whole  concluded  by 
affording  only  a  hard  ftratum  of  green  matter,  refembling  mal- 
achite. 

Copper  is  precipitated  from  its  folutions  by  iron.  For  this 
purpofe  nothing  more  is  required  than  to  leave  the  iron  in  on? 
of  the  folutions  of  the  other  metal,  which  need  not  be  ftrong. 
The  phenomenon  may  be  rendered  very  furprifing,  by  pouring 
the  folution  of  the  fulphate  of  copper  upon  the  clean  furface  of 
a  piece  of  iron  ;  for  this  furface  inftantly  becomes  covered  with 
copper.  The  copper  obtained  by  this  means,  is  known  by  the 
name  of  Copper  Cementation. 

This  precipitation  of  one  metal  by  another,  has  given  rife  to 
a  belief  that  the  iron  was  converted  into  copper  :  and  I  could, 
from  my  own  knowledge,  mention  the  names  of  individuals 
who  have  been  impofed  on  by  this  phenomenon. 

Copper  mixes  with  moft  of  the  metals  ;  and  forms — 

1.  With  arfenick,  the  white  tomback. 

2.  With  bifmuth,  an  alloy  of  a  reddifh   white   colour,    wit 
cubick  facets. 

3.  With  antimony,  a  violet-coloured  alloy. 

4.  It  may  be  combined  with  zinc  by  fufion,  or  by  cementa- 
tion with  lapis  calaminaris.  By  the  firit  procefs,  fimilor,  or 
the  Manheim  gold,  is  obtained  5  the  produce  of  the  fecoud  i: 
ferafs. 


Habitudes  of  Copper,  3^7 

5.  Copper,  plunged  in  a  folution  of  mercury,  aflumes  a  white 
tolour,  which  arifes  from  the  mercury  which  is  difplaced  by  the 
copper. 

6.  Copper  is  eafily  united  with  tin  ;  and  on  this  depends  tlie 
art  of  tinning  ;  for  which  purpofe  it  is  neceflary  to  clean  the  fur- 
face  of  the  metal  perfecSlly ;  becaufe  the  oxides  do  not  combine 
with  the  metals.  This  fird  obje£^  is  accompliflied  by  rubbing 
the  metals  intended  to  be  tinned  with  the  muriate  of  ammoni- 
ack,  or  by  fcraping  it  efFeflually  ;  or  even  by  paffmg  a  weak  acid 
6vcr  its  whole  furface.  After  this  operation  the  tin  is  applied 
by  fufing  it  in  the  veflel  intended  to  be  tinned,  then  fp reading 
k  about  with  old  rags  rolled  up  v  and  the  oxidation  of  thefe  met- 
als is  prevented  by  means  of  pitch. 

Copper,  fufed  with  tin,  forms  bronze,  or  bell-metal.  This 
alloy  is  more  brittle,  whiter,  and  more  fonorous,  in  proportion 
to  the  quantity  of  tin  that  enters  into  its  combination  :  it  is 
then  ufed  to  make  bells.  When  it  is  intended  to  be  applied  to 
the  purpofe  of  cafting  ftatues,  or  forming  great  guns,  a  larger 
proportion  of  copper  is  ufed  ;  becaufe  in  this  cafe  folidity  is  one 
of  the  firil  requifites. 

7,  Copper  and  iron  contra«£l:  very  little  union. 

8.  Copper,  alloyed  with  fiiver,  renders  it  more  fuiible ;  and 
thefe  two  m.etals  are  combined  to  form  folders.  Hence  it  is  that 
verdigris  is  occafionally  obfervcd  in  pieces  of  (ilver,  at  thofe  parts 
where  joinings  have  been  made  by  means  of  the  folder. 

Copper  precipitates  fiiver  from  its  folution  in  the  nitrick  acid. 
This  method  is  ufed  in  the  mints  to  feparate  the  fiiver  from  the 
acid,  after  the  operation  of  parting. 

Copper  is  very  much  uftd  in  the  arts.  All  the  boilers  in  dye. 
houfes  which  are  intended  to  contain  compofirions  that  do  not 
attack  this  metal,  are  made  of  copper. 

It  is  at  prefent  ufed  as  a  fliealhing  for  the  bottom  of  (hips. 
All  our  kitchen  utenfils  are  made  of  it ;  and,  in  fpite  of  the  dan- 
ger to  which  we  are  daily  expofed  of  being  poifoned,  and  not- 
withftanding  the  flow  and  den:ru£live  impreflion  this  metal  can- 
not but  produce  upon  us  individually,  there  are  few  houfes 
from  which  this  metal  is  yet  banifhed.  It  is  a  defirable  obje£l 
that  a  lavv  might  be  palTcd  to  prohibit  its  ufe  amongft  us  ;  as  has 
been  done  in  Sweden,  at  the  folicitation  of  the  Baron  deSchof- 
fer,  to  whom  the  publick  gratitude  has  erected  a  llatue  of  the 
fame  metal.  It  is  an  allowable  infringement  of  perfonal  liberty, 
when  government  take  upon  them  to  dire£lthe  conduct  of  indi- 
viduals in  fuch  a  manner  as  to  fecure  their  own  fafety.  There 
is-no  year  pafles  in  whicli  feveral  perfons  are  not  poiibned,  by 
hams,  or  other  food  which  is  fu  Jcrcd  to  remain  in  cooner  veflels. 


368  Properties  of  Mercury* 

Tinning  is  not  a  complete  remedy  againfl  this  danger  ;  j&r  it 
leaves  an  infmiry  of  points  where  the  copper  is  uncovered.* 

The  fulphate  of  copper  is  very  much  ufed  in  dying.  The 
cryftals  of  Venus,  aiid  verdigris,  are  likewife  ufed  in  painting  5 
they  enter  into  the  compofition  of  colours,  varnifhes,  &c. 

The  various  alloys  of  copper  with  other  metals,  renders  it 
highly  valuable  in  the  arts.  Brafs,  bronze,  and  bell-metal,  are 
very  extenfively  ufeful. 


CHAPTER    XIL 

CGficernitig    Mercury, 

MERCURY  differs  from  all  other  metals,  by  its  property  of 
•retaining  the  fluid  fiate  at  the  ordinary  temperature  of  the  at- 
mofphere.  . 

It  polleffes  the  met^lllck  opacity  and  brilliancy  ;  and  even  ac- 
..quires  malleability  when  deprived  of  fluidity  by  a  proper  degree 
of  cold.     The  beft  afcertained  experiment  which  has  been  made 
jOn  this  phenomenon,  was  performed  by  the'  Academy   of  Pe- 
.jiterfburg,  in, 1759.     The   natural  cold  was  increafed  by  a  mix- 
%ture  of  fnow  and  highly  concentrated   nitrick  acid  ;     and    the 
thermometer  of  De  Lifle    was  caufed  to  fall   to    213    degrees, 
which  correfponds  with  46  belov/  o  of  Reaumur.      At  this  pS- 
*xiod  the  mercury  appeared  to  defcend  no  lower;  the  bulb  of  the 
[thermometer  being  then  brpkeh^  the  metal  was  found  to  be  in  a 
'coi^gealed  ilate,    and  bore  to  be  flattened  by  the  hammer.     Mr. 
'Pail^s  congealed  mercury,  in  1772,  at  Krafnejark,  by  the  natural 
^cokl .:'  lie  then,  found  that  it  refembled  foft  tin.     It  has  been  af- 
certained' in  England  that  the  degree  of  its  congelation  was  the 
3 2d  of  Reaumur.  '  Mr.  Matthew  Gutherie,  conful  at  the  court 
of  the  Emprefs  of  RufFia,  proved  that  the  degree  of  cold  of  thl$ 
;Cdrigelati6ri  was  32  degrees  below  o  of  Reaumur;    and  that. 
'\vhen  the  mercury  is  purified  by  antimony,  it  congeals  at  2    de- 
gfee'siower'.-^— See  the    Journal    Encyclopedique,    September, 

*.It  maybendcsbe'  doubted  whether  the  extremely  thin  white  coating, 
XvlticK  conceals  the  iiiterruil  furface  of  tinned  copper,  be  not  a  kindof  beii 
or  fpeculum  metal,  infteacl  of  tin,  as  it  is  generally  fuppofed  to  be*.  T. 
^  ^  r^ranacpount  of  this  ftibje£t,  lee  Dr.  Blagden's  Hiftory  of  the  Con- 
gelation of  Mercury,  in  idje  f€^yei\ty^lhird^v  of  the  Philofophica 
Tranflidions. 


br^J  of  Mercury.  3^^ 

Mercury  is  as  indeflru£llble  by  fire  as  gold  and  filver  ;  and 
{ts  properties  in  general  have  caufed  it  to  be  arranged  ambtig  the 
perfc£t  metals. 

A  cubick  foot  of  this  metal  wieighs  949  pounds  ;  and  its  fpe- 
cifick  gravity  is  13.5681. — Briflbn. 

Mercury  has  been  found  in  the  earth  In  five  different  ftates. 

I.  Virgin  Mercury  is  found  in  mdft  of  the  mines  of  this  metal. 
Heat  alone,  or  mechanical  divifion  of  the  ore,  is  fufficient  to  ex- 
hibit it  in  the  metallick  form. 

Native  mercury  has  been  foimd  in  digging  the  foundations  of 
fome  houfcs  at  Montpellier  ;  and  this  metal  has  been  conftant- 
ly  mixed  and  coiifounded  with  a  grey  oi:  red  clay,  which  forms 
a  bed  almod  continuous,  at  a  few  feet  beneath  the  foundation 
of  this  town. 

The  obfervations  which  1  have  had  occafeoh  to  make  on 
this  fubjedl,  have  afcertained  that  the  mercury  exifts  in  1 
itratum  of  decompofed  grit-ftone,  very  argillaceous,  ferru- 
ginous, and  ochreous  ;  of  a  red,  brown,  or  grey  colour.  In 
this  clay,  the  globules  of  mercury,  in  confiderable  abundance, 
were  eafily  diftinguiftiable,  lying  upon  greyifh  plates.  Traces 
are  perceived  which  refemble  dendrites  ;  and  its  imprelTions  are 
formed  by  layers  of  the  oxide  of  mercury. 

Several  pounds  of  mercury  have  likewife  been  found  in  ai 
well  at  Vienne  in  Dauphiny  j  and  Mr.  Thoiivenel  has  pointed 
out  to  us  three  mines  of  this  metal  in  the  (ingle  province  of 
Dauphiny,  according  to  the  indications  of  Bleton. 

2.  Mr.  Sage  read  to  the  Academy,  on  the  i  ith  of  May,  17  81, 
the  analyfis  of  an  ore  of  mercury,  in  the  form  of  a  folid  oxide, 
which  came  from  Idria  in  1^'riuli.  It  is  of  a  brown  red  colour^ 
and  its  fradlure  is  granulated.  It  is  reducible  by  mere  heat  ; 
and  affords  oxigenated  gas.  It  emits  only  half  the  quantity  af- 
forded by  red  precipitate ;  becauie  this  oxide  contains  metallick 
imercury.  It  affords  ninety-one  pounds  of  mercury  per  quintaJ, 
and   a  fmall  quantity  of  filver. 

3.  The  muriate  of  mercury,  or  corneous  mercury,  has  been 
found  native  in  the  mine  of  Mufchel-Lamburg,  in  the  dutchy  of 
Deux-Ponts.  Mr.  Sage  obtained  eighty-fix  pounds  of  mercury 
per  quintal. 

Mr.  Woulfe  has  likewife  difcovered.  In  1776,  a  very  ponder- 
ous white,  green,  or  yellow  cryfiallized  ore  of  mercury ;  iri 
which  he  proved  the  exiftence  of  the  fulphurick  and  muriatick 
acids. 

4.  Mercury  is  fometimes  naturally  amalgamated  with  ©the? 
metals,  fuch  as  gold,  filver,  arfenick,  copper,  &c, 

2...Y 


370  Jllbies  of  Almaden. 

5.  Mercury  Is  ufually  mineralized  by  fulphur ;  and  the  pro- 
du6l  is  cinnabar  or  jethiops,    accori^.ing  to  the  colour. 

Cinnabar  is  found  under  different  forms,  i.  In  red  cryftals, 
confiRing  of  two  triangular  pyramids,  truncated,  and  joined  bafe 
to  bafe,  or  elfe  feparated  by  a  very  fhort  intermediate  prifm. 
Cinnabar  has  likewife,  been  found  cryftallized  in  tranfparent 
plates. 

2.  Cinnabar  is  almoft  always  found  in  maffes,  more  or  lefs 
compa.(fl  ;  the  colour  varies  from  deep  black  to  the  brightert  red. 
In  this  lad  (late  it  is  diftinguifhed  by  the  name  of  vermillion. 

Cinnabar  has  for  its  gangue,  quartz,  clay,  calcareous  earth, 
ponderous  fpar,  and  even  coal  The  ore  which  the  Germans 
called  Brandertz,  has  for  its  gangue  a  bituminous  matter,  which 
burns  perfedlly  well  -,  and  it  affords  only  fix  pounds  of  mercury 
in  the  quintal. 

The  principal  Cinnabar  mines  which  are  wrought  in  Europe, 
are  thofc  of  the  Palatinate  and  thofe  of  Spain.  Mr.  Sage  in- 
formed us,  in  1776,  of  the  procefsufed  in  the  Palatinate  ;  and 
we  are  indebted  to  Mr.  De  Juffieu  for  a  defcription  of  the  meth- 
od ufed  in  Spain. 

In  the  Palatinate,  the  pounded  and,  fifted  ore  is  mfxed  with 
one  third  of  lime  -,  and  the  mixture  introduced  into  iron  cucur- 
Ijits,  one  inch  thick,  three  feet  nine  inches  long,  one  foot  wide, 
with  an  opening  of  five  inches.  Thcfe  veffels  are  difpofed  in  a 
gallery.  Forty-eight  of  thefe  retorts  being  arranged  in  two 
parallel  lines,  a  fecond  row  is  placed  above  the  firft.  To  the 
neck  of  each  cucurbit  an  earthen  pot  is  adapted,  which  is  one 
third  filled  v/ith  water,  and  accurately  luted  on.  The  gallery 
is  heated  at  the  twp  extremities ;  fcveral  apertures  formed  in  the 
(^ome.  ferve  the  purpofe  of  chimneys  ;  and  the  diilillation  is  ef- 
fe(^ed  by  a  nre  kept  up  for  ten  or  twelve  hours. 

This  procefs  was  followed  at  Almaden  till  the  yeaV  1647, 
when  the  following  v/as  adopted,  as  being  more  fimple  and  eco- 
nomical. The  furnace  is  twelve  feet  high,  and  fourTeet  and  an 
half  diameter  within.  At  the  diftance  of  five  feet  and  an  half 
from  the  ground,  is  an  arch  upon  which  the  ore  is  difpofed,  and 
a  fire  is  kindled  in  the  afh-hole.  The  fublimed  mercury  efcapes 
through  twelve  apertures  formed  in  the  upper  part  of  the  labor- 
atory. To  thefe  apertures,  rows  of  aludels,  inferted  one  in  the 
other,  are  adjuftied,  and  difpofed  parallel  upon  at  terrace,  which 
terminates  in  a  fmall  building  fepafated  into  as  many  chambers 
as  there  are  files  of  aludels,-,  JIach  chamber  has  a  cavity  in  the 
middle,  to'receive  the  fmall  quuTitity  of  mercury  which  nray  ar- 
rive to  that  didance. 


Congelation  cf  Ahrcury,  27 1 

Every  furnace  contains  tv/o  hundred  quintals  of  cinnabar, 
and  the  fire  is  kept  up  for  three  days.  The  fulphur  which  burns 
is  dilengaged  in  the  form  of  fulphureous  acid,  and  efcapes 
through  fmall  chimneys  made  in  each  chamber.  Every  repeti- 
tion of  the  procefs  afibrds  from  twenty-five  to  fixty  quintals  of 
mercury. 

The  mine  of  Almaden  has  been  wrought  from  time  immemo- 
rial. Its  veins  are  from  three  to  fourteen  feet  in  breadth  j  and 
their  breadth  is  even  larger  vi'here  they  join. 
-  Hitherto  no  method  has  been  difcovered  to  fix  mercury  but 
that  of  extreme  cold.  This  metallick  fubftance,  naturally  fluid, 
is  capable  of  rifmg  even  by  a  very  moderate  fire  ;  as  is  proved 
by  an  experiment  of  Mr.  Achard,  who  having  left  a  difh  contain- 
ing twenty  pounds  of  mercury  over  a  furnace  which  was  daily 
heated,  experienced  a  falivation  at  the  end  of  feveral  days  j  as 
did  likewife  two  other  perfons  who  had  not  quitted  the  cham- 
ber. He  eitimates  this  heat  at  about  eighteen  degrees  of  Reau- 
mur.— Journal  de  Phyfique,  October,  1782. 

It  is  dangerous  to  oppofe  the  evaporation  or  dilatation  of  this 
metal  which  is  produced  by  heat. 

In  the  year  1732  an  alchemift  prefented  himfelf  to  Mr.  GeofF- 
roy,  pretending  he  had  difcovered  the  means  of  fixing  mercury. 
He  inclofed  the  metal  in  an  iron  box,  and  this  box  in  live  others, ' 
which  were  placed  in  a  furnace  ;  the  explofion  was  fo  ftrong, 
that  it  burfl  through  the  boards  of  the  floor.  Mr.  Hellot  has 
related  a  fimilar  fa£l  to  the  Academy. 

Mercury  boils  in  the  fame  manner  as  other  liquids  when  it  is 
heated  ;  and  for  this  purpofe  it  does  not  even  require  a  very  con- 
fiderable  heat  j  the  ebullition  confifl:s  merely  in  its  tranfition  to 
the  vaporous  ftate  :  for  it  may  be  diftilled  like  all  other  fluids, 
and  by  that  means  cleared  of  its  impurities.  Boerhaave  had  tlie 
patience  to  diflil  the  fame  mercury  five  hundred  times  fuccef- 
fively  :  and  the  metal  fufFcred  no  other  change,  than  that  it  af- 
forded a  grey  powder,  which  required  only  trituration  to  convert 
it  again  into  running  mercury. 

Mercury  is  not  eafily  changed  in  the  air  ;  but  if  the  a<5lion  of 
the  air  be  aflifted  by  heat,  the  mercury  gradually  lofes  its  fluidi- 
ty -,  and  at  the  end  of  feveral  months  forms  a  red  oxide,  which 
alchemifts  have  diftinguiflied  by  the  name  of  Precipitate  per  fe. 
The  apparatus  made  ufe  of  for  this  operation  is  ^^ery  large  and 
very  flat  bottle,  clofed  with  a  Hopper,  in  which  there  is  a  capil- 
lary perforatioi\.  The  mercuryw  ithin  the  bottle  by  this  meaas 
pofTefl^es  the  contaft  of  air  ;  and  by  difpofing  the  apparatus  upon 
a  fand  bath,  and  keeping  up  the  (late  of  ebullition  in  the  fluid, 
the  oxide  may  be  obtained  in  the  courfe  of  feveral  months. 


372  A^ion  ef  Acids  on  Mercury. 

This  oxide  gives  out  its  oxigene  by  fimple  heat,  without  an^j 
ntermedium  \  and  the  mercury  refumes  its  metallick  form  ;  one 
ounce  affords  about  a  pint.  A  quintal  of  mercury  takes  up  a- 
isout  eight  pounds  of  oxigene.  The  red  oxide  of  mercury,  ex- 
pofed  to  heat,  fubiimes  in  clofe  vefTels,  and  may  be  converted  in- 
to a  very  beautiful  glafs.  I  have  obfervcd  this  on  all  occafions 
when  I  have  made  th^  red  oxide  by  means  of  the  nitrick  acidj^ 
according  to  the  procefs  virhich  I  (hall  immediately  defcribe. 

It  is  certain  that  mercury  upon  which  water  is  boiled,  com- 
municates a  vermifuge  property  to  that  liquid,  though  the  mofi 
accurate  experiments  of  Lemery  have  (hewn  that  the  metal  does 
not  perceptibly  lofe  weight ;  which  proves  that  the  principle 
taken  up  by  the  water  is  very  fugaceous,  and  fo  light  that  it 
does  not  conftitute  any  fenfible  part  of  the  weight.  Water, 
which  has  remained  for  a  certain  time  over  mercury  contrails  a 
very  evident  metallick  tafte, 

1 .  The  fulphurick  acid  does  not  a£l  upon  mercury  unlefs 
affifted  by  heat.  In  this  cafe,  fulphureous  gas  is  difcngaged  ; 
and  a  white  powder  falls  down,  the  quantity  of  which  becomes 
greater  in  proportion  as  the  acid  is  decompofed.  This  oxide 
weighs  one  third  more  than  the  mercury  made  ufe  of.  It  is 
cauilick :  if  hot  water  be  poured  on  it,  it  becomes  yellow  ;  and 
if  it  be  urged  by  a  violent  heat,  it  affords  oxigenous  gas,  and 
the  mercury  refumes  its  natural  form.  This  yellow  oxide, 
obtained  by  means  of  the  fulphurick  acid,  is  known  by  the 
name  of  Turbith  Mineral.  It  has  long  been  confidered  as  a 
fulphate  of  mercury.  Mr.  Baume  has  proved  that  it  does  not; 
contain  a  particle  of  acid ;  and  it  appears  that  the  water  which 
develops  its  yellow  colour,  feizes  the  fmall  quantity  of  undecom- 
pofed  acid  which  was  mixed  with  the  oxide.  If  the  water 
which  has  been  poured  on  it  be  evaporated,  a  fait  is  obtained  in 
fmail,  foft,  and  deliquefcent  needles,  which  may  be  deprived  of 
their  acid  by  the  fimple  affufion  of  water.  This  fluid  precipi- 
tates the  mercury  from  them  in  the  form  of   turbith. 

2.  The  nitrick  acid  of  commerce,  at  the  ftrength  of  thirty- 
five  degrees,  diiTolves  mercury  with  violence,  even  without  the 
afiiilance  of  heat.  This  folution  is  accompanied  with  the  dif- 
cngagement  of  a  conliderable  quantity  of  nitrous  gas;  be- 
caufe  it  is  neceffary  that  the  acid  fhould  reduce  the  metal  to  the 
ftatc  of  oxide?  before  it  can  a£l  upon  it.  One  part  of  the  acid 
is  confequently  employed  in  difpofing  the  metal  for  folution,' 
a^nd  the  other  diiTolves  it  in  proportion  as  it  is  oxided.  This  is' 
what  happens  when  the  fulphurick  acid  is  digefted  upon  a  met- 
al ;  one  portion  is  decompofed,  and  reduces  the  metal  into  an 
^xide,  while  the  other  diflblves  it. 


Mercurial  Salts ^  j^j 

The  manner  of  effecting  the  folution  of  mercury  in  the  nl- 
trick  acid,  has  an  influence  on  the  properties  of  the  mercurial 
nitrate.  Bergmann  has  oblerved  that  the  folution  which  is 
made  flowly  and  quietly,  without  difengagement  of  nitrous  gas, 
affords  no  precipitate  on  the  addition  of  water ;  whereas  that 
which  is  made  by  the  afliftance  of  heat,  and  with  lofs  of  nitroug 
gas,  affords  a  precipitate.  It  appears  that  the  nitrick  acid,  affift- 
ed  by  heat,  is  capable  of  becoming  loaded  with  an  excefs  o£ 
mercurial  oxide,  which  it  lets  fall  when  diluted  with  water. 

The  method  of  performing  the  folution,  and  the  procefs 
made  ufe  of  to  cryftallize  it  has  an  equal  influence  upon  the 
form  of  the  cryftals.  i.  The  folution  made  in  the  cold,  and  left 
to  fpontaneous  evaporation,  affords  cryftals  which  appeared  to 
Mr.  De  Lifle  to  be  oftahedral  pyramids,  truncated  near  their 
bafe,  and  having  the  four  angles  refulting  from  the  jumfiion  of 
the  bafes  of  their  pyramids  likev/ife  truncated.  2.  If  the  fame 
folution  be  evaporated,  long  and  acute  blades  are  obtained,  lay- 
ing one  upon  the  other,  and  ftriated  obliquely  acrofs.  3.  The 
folution  of  mercury  effected  by  heat,  affords  flat  and  acute  nee* 
dies,  flriated  lengthways. 

The  nitrate  of  mercury  is  corrofive  ;  it  detonates  upon  coals 
when  it  is  very  dry,  and  emits  a  whitifh  flame  of  confiderablc 
^jrilliancy. 

The  mercurial  nitrate,  heated  in  a  crucible,  is  fufed,  and 
emits  a  confiderablc  quantity  of  nitrous  gas  together  with  it$ 
water  of  cryftallization.  The  remaining  oxide  becomes  yellow  ; 
and  at  length  afTumes  a  lively  red  colour,  and  forms  the  fub- 
flance  called  Red  Precipitate.  In  order  to  make  a  very  fine 
red  precipitate,  the  mercurial  folution  muft  be  put  into  a  retort, 
^^nd  diftilled  until  no  more  vapours  come  over.  An  additional 
quantity  of  nitrick  acid  muft  then  be  poured  on  the  remainder, 
and  likewife  diftilled  off.  After  three  or  four  repeated  diftilla- 
tions,  a  very  beautiful  precipitate  is  obtained  in  fmall  cryftals  cf 
a  very  fuperb  red  colour. 

The  folution  of  mercurial  nitrate  forms  mercurial  water.  It 
is  of  ufe  to  afcertain  the  prefence  of  fulphurick  and  muriatick 
falts  in  mineral  waters. 

The  acids,  the  alkalis,  the  earths,  and  fome  of  the  metals, 
likewife  precipitate  mercury  from  its  folution  in  the  nitrick  acid. 
Thefe  precipitates  always  confift.of  the  oxides  of  mercury  in  a 
greater  or  lefs  degree  of  perfection,  nccording  to  which  circum- 
ifUnces  their  colour  is  I'ubjedl  to  variation.  On  this  head, 
Lemcry,  Baume,  &c.    n;ay  b^confulted. 

Mr  Bayen  has  difcovered  tlmt  feme  of  thefe  precipitates  pof«. 
fefs  the  property  of  fulminating,    when    mixed    with   a  fmall 


374  Fulm'maiwg    Mercury, 

quantity  of  fublimed  fulphur.  This  chemifl  has  pointed  ©ut 
t|iree — i.  The  precipitate  of  mercury  from  its  folution  in  the 
fttrick  acid,  by  the  affiftance  of  the  carbonate  of  ammoniack. 
2.  The  precipitate  of  the  fame  fluid  by  lime-water.  3.  The 
precipitate  of  the  folution  of  corrofive  fublimate  by  lime-water. 
Half  a  gros  is  to  be  triturated  with  {\y.  grains  of  fublimed  ful- 
phur.  i^fter  the  detonation,  a  violet-coloured  powder  remains 
which  affords  a  fine  cinnabar  by  fublimation. 

3.  The  muriatick  acid  does  not  fenfibly  acEl  upon  mercury  ; 
but  if  it  be  digefted  for  a  long  time  upon  the  metal,  it  oxides  it, 
and  at  length  diflblves  the  oxide,  as  may  be  concluded  from  the 
experiments  of  Romberg,  inferted  in  the  volume  of  the  Acade- 
my of  Sciences  for  the  year  1700. 

The  muriatick  acid  completely  diflblves  the  mercurial  oxides. 
When  thcfe  oxides  are  nearly  in  the  metallick  ftate,  or  charged 
vith  a  fmall  quantity  of  oxigenc,  the  muriate  of  mercury  is 
formed.  When,  on  the  contrary,  the  oxide  of  mercury  is  fat- 
urated  with  oxigene,  the  oxigenated  muriate  of  mercury,  or 
corrofive  fublimate  of  mercury,  is  formed. 

Corrofive  fublimate  may  be  formed  according  to  two  methods  j 
in  the  dry  way,  or  in  the  humid  way. 

.  To  make  this  fait  in  the  dry  way,  the  operator  may  proceed 
in  various  manners. 

1.  Equal  parts  of  dried  nitrate  of  mercury,  decrepitated  mu- 
riate of  foda,  and  fulphate  of  iron  calcined  to  whitenefs,  arc 
mixed  together.  This  mixture  being  expofed  to  fublimation, 
the  product  which  arifes  is  corrofive  fublimate. 

2.  Rumiing  mercury  is  ufed  in  Holland  inftead  of  the  ni- 
trate of  mercury  ;  and  the  fame  refults  may  be  obtained  by  u- 
Ijng  any  oxide  of  mercury  whatever. 

3.  Equal  parts  of  the  fulphure  of  mercury,  and  the  decrepi- 
tated muriate  of  foda,  afford  the  fame  fait  by  fublimation. 
TJiis  procefs  of  Kunckel  has  been  revived  by  Boulduc. 

4.  Mr.  Ivlonnet  affures  us  that  he  obtained  corrofive  fubli- 
fj^ate  by  treating  the  dry  muriate  of  foda,  and  a  mercurial  oxide, 
in  the.wayofdilUllationin  a  retort. 

If  mercury  be  diiTolvcd  in  the  oxigenated  muriatick  acid,  the 
folution,  when  concentrated,  affords  very  fine  corrofive  fublimate. 
It  may  like  wife  be  obtained  by  precipitathig  the  mercury  from 
jBicrcurial  water  by  the  fame  agid,  and  evaporating  the  folution. 

I  have  .obtained  very  fine  fublimate  by  prefenting  a  mercurial 
jBxide,  fufhcitutly  loaded  with  oxigene,  to  the  ordinary  muriatick 
acid.  One  pound  of  muriatick^jfcd,  at  the  Itrength  of  twenty- 
Hoe  degrees,  poured  upon  one  pjWid  or  red  oxide  by  the  nitrick 
aiid,:diicolours  It,  in  a  fliort  tim?ciiffolves  it  \^ith  a  violent  heat. 


Alereurlus  D^Icij\ 


37S 


riiy\  this  folut'ion,  diluted  "with  water,  and  properly  evaporated^ 
afff^rds  from  twelve  to  fourteen  ounces  of  cryllals  of  corrofivc 
fublimate.  0 

The  corrofive  muriate  of  mercury  has  a  flyptick  tafle,  follow- 
ed by  an  exceedingly  difagreeable  metallick  tafte.  When  plac-* 
ed  on  hot  coals,  it  is  diffipated  in  fumes  ;  when  flowly  heated 
in  fubllming  veflcis,  it  rifes  in  pvifmatick  cryftals,  fo  much  flat- 
tened, that  their  faces  are  fcarcely  diftinguiihable.  The  afTeL-i^ 
blage  of  thefe  has  induced  authors  to  compare  them  to  fword 
blades  lying  acrofs  each  other. 

This  fait  is  foluble  in  nineteen  parts  of  water  -,  and  when 
the  folution  is  concentrated,  it  affords  cryftals  fimilar  to  thofe 
obtained  by  fublimation. 

Barytes,  magnefia,  and  lime  decompofe  this  fait.  Half  a  gros 
of  corroiive  fublimate  in  powder,  thrown  into  a  pint  of  lime- 
water,  forms  a  yellow  precipitate.  This  fluid  is  known  by  the 
name  of  Phas^edcnick  Water. 

Fixed  alkali  precipitates  the  mercury  in  an  orange-coloured 
oxide  ;  and  volatile  alkali  in  the  form  of  a  white-'|Jd'wdcr,  which 
becomes  brown  in  a  Ihort  time. 

The  fame  muriatick  acid,  combined  with  a  lefs  perfe£!  oxide 
of  mercury,  forms  the  mild  muriate  of  mercury,  or  mercurius 
dulcis.  This  combination  may  likewife  be  made  by  two  meth-^ 
ods  -,  by  the  dry,  or  the  humid  way. 

I.  In  the  dry  v/ay,  four  parts  of  corrofive  muriate  of  mercu* 
ry  are  triturated  in  a  mortar  with  three  of  running  mercury. 
When  the  mercury  has  difappeared,  the  mixture  is  put  into 
phials,  and  fublimed  three  fucceflive  times,  in  order  that  the 
combination  may  be  more  accurate.  This  fublimate  diflers  from 
corrofive  fublimate  by  its  infolubllity  in  water,  its  infipidity,  and 
the  form  of  its  cryftals,  whicli  are  tetrahedral  pyramids,  term^ 
nated  by  four-fided  pyramids.  To  obtain  this  regular  form,  it 
is  necelfary  that  the  fubliaiation  fliould  be  made  at  a  moderate 
heat ;  for,  if  the  heat  be  fufficient  to  liquefy  the  fait,  the  refuk 
is  merely  cruft,  with  no  appearance  of  cryftals.  As  the  tritura- 
tion of  corrofive  fublin\ate  isdangercms,  on  account  of  the  pow- 
der which  rlfes,  Mr.  Baume  pours  a  fmall  quantity  of  water  upon 
the  mixture.  This  liquid  accelerates  the  trituration,  and  pre- 
vents the  rifing  of  the  dcftruc^^ive  powder. 

Mr,  Bailleau  has  propofcd  the  incorporating  of  corrofive  fub- 
limate with  water,  and  triturating  it  with  running  mercury. 
The  combination  is  completed  by  digefting  the  mixture  on  a 
fand  bath  by  a  gentle  heat.  The  matter  becomes  white,  and 
requires  only  a  fint^le  fublimation.  Whenever  it  is  fufpecled 
that  mercurius  dulcis  ftill  retains  a  portion  of  corrofive  fublimate. 


37<5  Alercunal   Mthiop. 

nothing  more  is  neceiTary  to  be  done  than  to  triturate  it,  and 
pour  boiling  water  upon  it  *,  for  by  this  means  the  whole  of  the 
foluble  fait  which  may  have  remained,  is  carried  ofF. 

Mr.  Baume  has  proved  that  there  is  no  intermediate  ftate  be- 
tween mercuriusdulcis  and  corrofive  fublimate.  If  lefs  mercury 
be  added  to  the  fublimate,  a  proportional  quantity  of  mercurius 
dulcis  only  fublimes,  and  the  reft  rifes  in  the  form  of  corrofive 
fubUmate  ;  if  a  greater  quantity  of  mercury  be  added  than  is  ne- 
ceiTary to  convert  the  whole  into  mercurius  dulcis  the  excefs  re- 
mains in  the  form  of  running  mercury. 

The  fame  chemift  has  likewife  proved,  that  a  portion  of  the 
mercury  is  always  loft  at  each  fublimation ;  and  that  a  fmall 
(quantity  of  corrofive  fublimate  is  formed,  which  arifes  from  the 
alteration  of  the  mercury.  Hence  it  follows  that  the  mercurial 
panacea,  which  is  made  by  fubliming  mercurius  dulcis  eight  or 
nine  times,  is  a  more  fufpicious  remedy  than  the  mercurius 
dulcis  itfelf. 

2.  Mercurius  dulcis  may  likewife  be  made  by  decompofing 
mercurial  water  by  a  folution  of  the  muriate  of  foda.  The 
white  precipitate  which  is  obtained  may  be  fublimed,  and  forms 
an  excellent  mercurius  dulcis.  I  communicated  this  procefs  to 
the  Society  of  Sciences  at  Montpellier  two  years  before  Mr. 
Scheele  made  it  known. 

The  corrofive  muriate  of  mercury  differs  therefore  from  the 
mild  muriate  by  the  ftate  of  its  acid. 

The  mercurial  oxides  are  equally  foluble  in  the  other  acids. 

3.  A  folution  df  borax,  mixed  with  mercurial  water,  forms  a 
very  abundant  yellow  precipitate,  which  is  nothing  elfe  but  the 
combination  of  the  acid  of  borax  and  mercury.  A  fmall  quan- 
tity of  this  fait  remains  in  folution,  which  may  be  obtained  iii 
brilliant  cryftals  by  evaporation. 

'4.  The  acetous  acid  likewife  diflblves  the  oxide  of  mercury^ 
and  affords  white  foliated  cryftals. 

Mercury  precipitated  from  a  folution  of  the  acetate  of  mer- 
curyi  combines  with  the  acidulous  tartrite  of  pot-afti,  and  forms 
vegeto-mercurial  water  of  Preffavin. 

The  acetate  of  mercury  is  the  bafis  of  Keyfer's  pills. 

'5.:  Mercury,  artificially  mixed  with  fulphur,  forms  the  red  or 
black  fulphures,  known,  on  account  of  their  colour,  by  the  names 
of  iEthiops  CT  Cinnabar. 

To  form  the  -ffithiops,  or  black  oxide  of  mercury,  three  meth- 
ods maybe  followed. 

I .  Four  ounces '  of  friercury  may  be  triturated  with  twelve 
outicesof'Tublimecffdlf^hur  in  a  glafs  mortar.  TJie  r<;falt  is  a 
black  powder,  called  Athiops  Mhicral. 


Mercurial  Mthiops,  3^7 

'  2.  Four  ounces  of  fiilphur  may  be  fufed  In  a  crucible,  and  one 
ounce  of  mercury  extinguiflied  in  it.  The  mixture  readily  takes 
fire,  but  the  inflammation  is  to  be  prevented  \  and  the  blackifii 
relidue,  being  pounded,  affords  a  greerlifli  powder,  which  ia  a 
true  asthiops. 

3.  The  aethiops  may  be  made  by  pouring  the  fulphure  of 
pot-afh  upon  mercurial  water. 

Thefe  xthiops  afford  by  fublimatibns  clnnabai*,  or  the  red 
fulphurated  oxide.'  But  iil  order  to  make  it  with  a  greater  de- 
gree of  accuracy,  four  ounces  of  fublimed  /fulphur  are  fufed  in 
an  unglazed  earthen  pot,  and  one  pound  of  mercury  mixed 
with  it  by  ftlrring  or  agitation.  When  thefe  fubftances  have 
combined  to  a  certain  degree,  the  mixture  fpontaneoully  takes 
fire,  and  is  fuffered  to  bUrn  about  a  rhinute.  The  flame  is 
then  fmothered,  and  the  refiduepulverifed,  which  forms  a  vio- 
let powder,  ufually  weighing  about  feveriteen  ounces  five  gros. 
This  powder  being  fublimed,  affords  a  fublimate  of  a  livid  red 
cblour ;  which,  when  poUnded,  exhibits  a  fine  red  colour, 
known  by  the  name  of  Verrni|lion. 

Three  parts  of  cinnabar,  mixed  with  two  ounces  of  iron  fil- 
ings, afford  very  pure  mercury  by  diftillation,  which  is  called 
mercury  revived  from  cinnabar.  Lime,  the  alkalis,  and  molt 
of  the  metals,  may  be  fubllituted  inilead  of  the  iron. 

Mercury  amalgamates  with  mod  other  metals.  Oa  this 
property  is  founded  the  art  of  water-gilding,  or  gilding  upon 
metals,  the  tinniiig  of  glafies,  the  working  of  gold  and  fiiver 
mines,  &c. 

Mercury  is  likewife  ufed  Iri  the  conftruiflion  of  meteorologi- 
cal inftruments,  in  which  it  poffeffes  the  advantage  over  other 
fluids — I.  That  it  does  not  eafily  freeze.  2.  It  is  more  eafily 
and  gradually  dilatable,  according  to  the  fine  experiments  of 
Meflrs.  Bouquet  and  Lavoider.  3.  It  is  very  nearly  of  the  fame 
quality,  in  different  fpecimens. 

Mercury  may  be  ufed  in  fubftance  as  a  remedy  a^aihft  the 
volvulus,  and  it  has  rlevCr  been  obfervcd  to  produce  bad  effects. 
It  is  mixed  with  fat,  to  form  unguents  very  much  ufed  in  venere* 
al  cafes.  Thefe  are  prepared  with  one  third  or  half  their  weight 
of  mercury,  according  to  the  exigence  of  the  cafe. 

The  mercurial  water  is  ufed  as  an  efcharotick. 

The  red  oxides  anfwerthe  fame  purpofc. 

The  mild  mercurial  niiiriate  is  ufed  as  a  purgative.  It  en- 
ters into  the  compofition  of  pills  which  are  ufed  in  venereal  caf- 
es, with  the  intention  of  carrying  off  the  morbifick  matter  by 
«he  ficin. 

2...Z 


378  Native  Stiver, 

The  corrofive  muriate  of  mercury  is  of  vety  extenfive  ufe, 
more  efpecially  againft  venereal  diforders.  This  remedy  re- 
quires {kill  and  prudence  •,  but  I  have  received  it  as  the  com- 
mon opinion  of  all  phyficians  of  reputation,  that  it  is  the  moft 
powerful  and  certain  remedy  poflefled  by  the  art  of  medicine. 
In  a  large  dofe  it  irritates  the  fyftem,  afFcdls  the  flomach,  occa- 
fions  fpafms  in  the  lower  belly,  and  leaves  impreflions  which 
are  difficult  to  be  eradicated. 

Cinnabar  is  ufed  in  fumigations,  to  deftroy  certain  infe£ls 
which  attach  themfelves  to  the  (kin.  It  is  iikewife  ufed  as  a 
pigment. 


CHAPTER  XIII. 

Concerning  Silver, 

.  SILVER  IS  a  metal  of  a  white  colour,  pofleffing  neither  fmell 
nor  tafte,  nearly  unalterable  by  fire,  very  du£lile  and  tenaceous. 
A  cubick  foot  of  this  metal  caft  weighs  feven  hundred  and 
twelve  pounds  j  the  fpecifick  gravity  of  caft  filver  is  10.1752. 
See  BrilTon.— It  is  found  in  the  earth  in  five  different  Hates, 
which  we  fhall  proceed  to  confider. 

1 .  Virgin  or  native  filver. — Native  filver  is  found  in  various 
forms.  I.  In  ramifications  compofed  of  ocftahedrons  inferted 
one  in  the  other.  This  variety  is  known  by  moft  mineralogifts 
under  the  name  of  Virgin  Silver  in  Vegetation.  Four  procef- 
fes,  indicated  by  Mr.  Sage,  are  known  for  the  cryftallization  of 
filver :  amalgamation,  redudtion  by  phofphorus,  redudion  by 
copper,  and  fufion. 

A  detail  of  thefe  four  procefTes  may  be  feen  in  his  Analyfc 
Chimique,  book  iii.  p.   238,  et  feq. 

Native  filver  is  Iikewife  found  in  fmall  capillary,  flexible,  and 
intertwined  threads.  The  decompoGtion  of  the  red  or  vitreous 
fdver  gives  rife  to  this  fpecies  ;  it  may  even  be  produced  by 
a  How  calcination  of  one  of  thefe  ores. 

Silver  is  Iikewife  found  in  irregular  forms  ;  either  in  fmall 
plates  difperfed  in  the  gangues,  or  in  mafles.  Albinus  reports, 
in  the  Chronicle  of  the  Mines  of  Mifnia,  that  in  the  year  1478, 
a  lump  of  native  filver  was  found  at  Schneeburg,  weighing  four 
hundred  quintals.  Duke  Albert  of  Saxony  defcended  into  the 
mine  to  fee  this  furprifing  mafs  of  filver,  and  had  dinner  ferved 
up  upon  it. 

2.  The  vitreous  filver  ore,  or  filver  minerahzed  by  fulphur. 
—This  ore  is  of  a  grey  colour,  and  may  be  cut  hke  lead.    It  cry  f- 


Ores  of  Silver,  3^p 

tallizes  in  oftahedrons,  or  in  truncated  cubes,  and  is  mod  fre- 
quently found  of  an  indeterminate  figure.  The  fulphur  may  be 
extraded  by  heat.  It  affords  about  fixteen  pounds  in  the  quin- 
tal 

When  the  fulphur  is  contained  in  a  greater  proportion  in 
this  ore,  it  becomes  black,  porous,  and  friable. 

3.  Red  filver  ore  :  filver  mineralized  by  fulphur  and  arfcn- 
ick. — This  fpecies  cryftallizes  in  hexahedral  pyramids,  termina- 
ting in  an  obtufe  trihedral  pyramid,  with  rhombick  faces.  It  is 
frequently  found  in  irregular  mafles  of  no  determinate  figure. 
It  poflefles  the  colour  and  tranfparency  of  the  ruby. 

Mr.  Sage  has  obtained  from  this  ore,  by  diftillation,  water, 
carbonick  acid,  and  the  fulphurated  yellow  and  red  oxides  of  ar- 
fenick.  If  this  ore  be  calcined  in  a  teft,  and  the  mineralizer  be 
fuffered  to  exhale,  the  refidue  is  found  to  be  in  the  metallick 
ftate,  exhibiting  contorted  threads  of  filver  at  its  furface.  Part 
of  the  filver  pafles  to  the  (late  of  grey  oxide  in  this  operation. 

4.  White  antimonial  fiiver  ore  :  filver  and  antimony  miner- 
alized by  fulphur. — This  ore  is  as  white  as  filver  ;  it  is  brittle, 
and  of  a  granulated  frafture.  Sometimes  it  is  found  in  hexa- 
hedral prifms,  truncated  and  flat  at  each  end  :  this  kind  is  found 
in  the  principality  of  Furltenburg.  When  expofed  to  heat,  it 
becomes  as  fluid  as  water,  emits  antimony  and  fulphur,  and 
leaves  the  filver  behind,  together  with  an  oxide  of  antimony. 
This  femi-metal  is  cleared  off  by  fufion,  afl^ifted  by  proper  fluxes^ 
and  cupellation. 

5.  The  corneous  ore  of  filver,  or  muriate  of  filver — This  fpe- 
cies is  of  a  dirty  yellow  grey  :  it  is  foft,  and  may  be  eafily  brok- 
en or  cut.  A  gentle  heat  caufes  it  to  flow  ;  it  fublimes  with- 
out decoirpofition,  is  moll  frequently  found  of  no  regular  form, 
but  fometimes  cryftallized  in  cubes.  The  muriatick  acid  is  its 
mineralizer.  Mr.  Woulfe  has  fliciwn  that  it  likewife  contains  a 
fmall  quantity  of  fulphurick  acid. 

6.  Silver  is  alfo  very  frequently  alloyed  with  various  metals, 
fuch  as  lead,  copper,  bifmuth,  cobalt  ;  and  thefe  ores  are  fome- 
times wrought  on  account  of  the  quantity  of  filver  they  contain. 

The  manner  of  working  a  filver  ore  varies  according  to  its 
nature  ;  but  all  the  procefl^es  ufed  in  the  various  countries  may 
be  reduced  to  the  following  : 

I.  In  Peru  and  Mexico  the  mineral  is  pounded,  roafled, 
waftied,  and  afterwards  triturated  with  mercury  in  copper  boil- 
ers filled  with  water  kept  at  the  boiling  heat.  The  whole  is  ag- 
itated by  means  of  a  kind  of  mill.  The  amalgam  is  afterwards 
exprefl^ed  in  a  flcin  ;  then  heated,  ta  drivj  oiF  the  remaining 
mercury  5  after  which  procefs  tlie  filver  remains  alone. 


2§(>  -4/%  of  %thsr. 

This  rneibod  is  defective — i.  Becaufe  the.  fire  volatilizes  ^ 
portion  of  the  muriate  of  filver  which  abounds  in  thefe  ores, 
2.  The  wafhings  carry  with  them  a  portion  of  the  cxide  of  fil- 
ver. 3.  The  mercury  does  not  amalgamate  either  with  the 
muriates  of  iilver,  or  the  fulphates  of  that  metal. 

2.  When  filver  ores,  mineralized  by  fulphur  or  arfenick,  at© 
tp  be  wrought,  they  are  roafted,  pounded,  waflied,  and  fufed 
with  lead.  This  metal  fei2es  all  the  filver,  from  which  it  is 
again  feparated  by  cupellation. 

3.  When  the  iilver  ore  is  poor,  it  is  fufed  with  cupreous  py- 
rites, and  the  mixture  treated  in  the  way  of  liquation.—- See  th^ 
article  Lead. 

To  determine  the  degree  of  purity  of  the  filver,  a  given  weight 
of  filyer  is  fuppofed  to  be  compofed  of  twelve  parts,  called  pen- 
ny weights  \  each  penny  v/eight  is  divided  into  twenty-four 
grains.  Silver,  clear  of  all  mixture,  is  faid  tp  be  twelve  penny 
weights  fine. 

In  order  toaflay  filver,  and  to  afcertain  its  degree  of  finenefs, 
trie  regulation  of  the  Court  of  Monies  of  France  prefgribes,  tha; 
thirty-fix  grains  of  filver  be  taken,  and  wrapped  in  a  plate  of 
lead  containing  no  fine  metal,  ^^nd  then  expofed  to  cupellation. 
From  the  lofs  which  the  button  of  filver  that  remains  on  the 
cuDel  h<is  fufPered,  a  judgment  is  made  of  the  quantity  of  alloy, 
rf  the  lofs  be  one  twelfth  of  the  whole,  the  filver  is  faid  to  be 
eleven  penny  weights  fine.  The  details  relating  to  this  opera- 
tion may  be  {>6^\\  in  VArt  d'ejifayr  l^Or  et  P Argent^  par  M.  Sage, 

Silver  m.ay  be  rendered  hard  by  mixing  it  v/ith  copper  ;  and 
for  this  reafon  it  is  alloyed  with  thatmeial  for  filverfmiths  work, 
as  well  as  for  the  coinage.  The  law  permits  one  twelfth  of  al- 
loy in  filver  money  •,*  and  It  is  tliis  porrion  pf  copper  which 
render?;  the  folution  of  filver  coin  in  the  nitrick  acid  blue. 

Silver  is  not  changed  by  the  ccntaft  of  air.  A  coiifidcrable 
heat  is  required  to  fufe  it  ;  but  it  may  JDe  volatihzed  by  (bong 
fire  without  alteration,  as  is  proved  bv  tUe  capital  experiments 
of  the  Academicians  of  Paris,  made  in  the  focus  of  the  lens  of 
Mr.  Trudainc.  'Phis  metal  emits  a  thick  fume,  which  whitens 
plates  of  gold  expofed  immediately  over  it. 

Junker  converted  filver  into  glafs,  by  treating  it  in  a  way  of 
reverberation,  after  the  manner  Ol  ffaacus  Holiandus,  in  a  very 
ftrong  fire. 

Macquer,  by  expofing  filver  twenty  tirnes  fuccefi*ively  to  the. 
porcelain  furnace  of  Seves,  obtained  glafs  of  an  olive  green  col- 
our.    It  was  likewife  obferved  that  this  metal,  when  expofed  tQ 

f  The  ^i'itifli  coinage  is  1 1  ounces  a  penny  v/ei^hts  5ne.    T' 


Habitudes  of  Silver.  38 1 

the  focus  of  a  burning  mirror,  prefented  a  white  pulverulent 
matter  on  its  fuvface,  and  a  greeni(h  vitreous  covering  on  the 
fupport  upon  which  it  was  placed. 

Though  thefe  experiments  clearly  prove  that  filver  Is  capable 
of  combining  with  oxigene,*  the  difficulty  which  is  found  in  ef- 
fecting this  combination,  and  the  facility  with  which  this  air 
is  difengagcd  from  the  oxides  of  filver,  prove  that  there  is  but 
Jittk  affinity  between  thefe  two  fubftances. 

If  filver  in  a  (late  of  extreme  divifion  be  prefented  to  the 
concentrated  and  boiling  fulphurick  acid,  fulphureous  gas  is  dif. 
engaged  :  the  filver  is  reduced  into  a  wiiite  matter,  which  is  a 
true  oxide  of  filver  ;  and  contains  a  fmall  quantity  of  fulphate, 
vhich  may  be  obtained  in  fmall  needles,  or  in  plates  formed  by 
the  union  of  thefe  needles  lengthways,  as  Mr.  De  Fourcroy  has 
pbferved.  This  fait  flows  by  heat,  and  is  very  fixed.  If  filver 
be  precipitated  by  metals  or  alkalis,  thefe  precipitates  are  reduci' 
ble  without  addition. 

The  nitrick  acid  difTolves  (ilver  with  rapidity  :  much  nitrous 
gis  is  difengagcd.  The  folution  is  at  firit  blue  :  but  this  colour 
tiiiappears  when  the  filver  is  pure  ;  and  degenerates  into  a  green 
<;:olour,  if  it  be  alloyed  with  copper.  The  nifrick  acid  is  capa- 
ble of  difl'olving  more  than  half  its  weight  of  filver.  The  folution 
tlien  lets  fall  cryitals  in  hexagonal,  triangular,  or  fquare  plates, 
wiiich  arecalledNitrateof  Silver,LunarCryffals,  LunarNitrCj&c. 
The  folution  of  thefe  cryflals,  generally  known  by  the  name 
of  Solution  of  Silver,  is  very  cauftick.  It  colours  the  ilcin  black, 
bunivS  the  epidermis,  and  focom'pletely  deftroys  its  orgiinization, 
tiiat  the  fpot  difappcars  only  by  the  renewing  of  the  fkin. 

The  nitrate  of  filver  melts  on  burning  coals  ;  but  if  it  be  ex- 
pofed  to  a  gentle  heat,  in  earthen  or  metallick  velTcls,  it  liquefies, 
and  may  then  be  caffc  in  moulds.  This  fufed  nitrate  of  filver 
forms  the  hpis  infernalis.  Care  mull  be  taken  to  pour  it  out 
^s  icon  as  it  is  fufed  ;  becaufe  otherwife  the  ncid  would  be  dif- 
engagcd, the  filver  would  be  revived,  and  the  lapis  infernalis,  or 
lunar  cauftlck,    would  lofe  its  virtue. 

Lapis  infernalis,  made  with  pure  iilver,  and  prepared  as  above 
defcribed,  is  whitiih  ;  whereas  it  is  blackiffi  when  fuflered  to  re- 
main in  fufion  for  any  time. 

Lapis  infernalis  is  very  frequently  mixed  wtrh  nitrate  of  cop- 
per. This  fraud  is  reprehenfible,  becaufe  it  is  an  alloy  which 
renders  wounds  of  a  bad  characler. 

The  lapis  infernalis  is  ufed  as  an  efcharotick,  and  to  corrode 
fungous  excrcfcences. 

Silver  may  be  precipitated  from  its  folution  by  lime-water, 
alkalis,  and  feveral  metals.  Thefe  lall  cxliibit  very  important 
phenomena. 


3S2  Habit  tides  of  Silver, 

1.  A  plate  of  copper,  immerfed  in  a  folution  of  filver  diluted 
in  water,  precipitates  the  metal.  It  adheres  at  the  moment  of 
precipitation  to  the  furface  of  the  copper,  where  it  forms  a  kind 
of  mofs.  In  proportion  as  the  filver  is  precipitated,  the  water 
affumes  a  blue  tinge  ;  which  proves  that  the  copper  is  diflblved 
in  the  nitrick  acid,  in  the  room  of  the  filver.  When  the  whole 
of  the  filver  is  difengaged,  the  water  is  to  be  decanted,  the  fil- 
ver dried,  and  fufed  in  crucibles,  to  be  Caft  into  ingots.  This 
filver  almoft  always  retains  a  fmall  quantity  of  copper ;  of 
which  it  may  be  deprived  by  cupellation  with  lead,  which  ren- 
ders the  filver  pure  j  this  procefs  is  ufed  in  the  mints,  where  the 
parting  operation  of  gold  from  filver  is  performed.  The  firft 
ftep  confifts  in  fcparating  the  filver  by  means  of  nitrick  acid  j 
and  this  is  afterwards  precipitated  by  the  addition  of  copper. 

2.  The  filver  is  hkewife  precipitated  by  mercury.  In  this 
operation  it  amalgamates  with  a  fmall  quantity  of  the  mercury, 
and  forms  tf  trahedral  cryflals  terminated  by  a  tetrahedral  pyra- 
mid, which  cryftals  are  articulated  into  each  other.  This  ar- 
rangement gives  tliem  the  form  of  a  vegetation  j  and  has  caufed 
the  precipitate  to  be  known  by  the  name  of  the  tree  of  Diana, 
Arbor  Diana.  Lemery,  Romberg,  and  other  chemifts,  have 
fncceflively  publiflied  procefies  to  produce  this  phenomenon  ; 
but  that  which  has  fucceeded  befl:  in  my  hands,  is  defcribed  by 
Wr.  Baume.  Six  gros  of  the  folution  of  filver,  and  four  of  that 
of  mercury,  both  well  fiiturated,  are  taken,  and  diluted  with  five 
ounces  of  diiliiled  water.  Thefe  are  to  be  put  into  a  conical 
veiTel ;  and  an  amalgam  of  (c\tn  parts  of  mercury,  and  one  of 
filver,  is  to  be  poured  in.  A  multitude  of  fmall  cryftnls  inflant- 
ly  appear  to  difengage  themfelves  from  the  furface  of  the  amal- 
gam, upon  which  new  ones  articulate  themfelves ;  and  a  veget- 
ation is  produced,  which  perceptibly  rifes  under  the  eye  of  the 
fpe^^ator.  To  render  this  phenomenon  more  itriking,  I  decant 
ihe  exhaufted  water,  and  fubftitute  frefh  ;  by  this  means  I  can 
fill  any  veflel  whatever  with  thefe  vegetations.  The  mercury 
amalgam.ated  with  the  filver,  in  this  operation,  may  be  feparated 
by  means  of  fire. 

The  nmriatick  acid  does  not  difiblve  filver,  but  it  fpeedily 
difiblves  its  oxides.  The  oxigenated  muriatick  acid  diflblves 
filver. 

To  produce  a  certain  and  fpeedy  combination  of  the  muri- 
atick acid  with  filver,  this  acid  is  to  be  poured  into  a  folution  of 
the  nitrate  of  filver.  A  precipitate  immediately  falls  down, 
which  is  known  by  the  name  of  Lmia  Cornea.  This  muriate 
of  filver  is  very  fufible  ;  and  runs  into  a  grey  and  tranfparent 
fubftance,  confiderably  rcfembling  horn.     If  a  ftronger   degree 


Fultninating  Si/vsr.  583 

of  heat  be  applied,  it  is  decompofed,  part  is  volatilized,  and  the 
other  part  reduced  into  filver. 

The  muriate  of  filver,  expofed  to  the  light  of  the  fun,  be- 
comes brown  in  a  fliort  time.  Oxigenous  gas  is  difengaged  ; 
which  may  be  collecfled  by  placing  it  under  water,  according 
to  the  procefs  of  Mr.  BerthoUet.  Moft  of  the  folutions  of  the 
metals  have  the  fame  property.  Lunar  nitre  likewife  becomes 
coloured,  and  emits  its  oxigene  and  nitrous  gas. 

One  pound  of  boiling  water  does  not  diflblve  more  than  three 
or  four  grains  of  muriate  of  filver,  according  to  the  obfervatioa 
of  Mr.  Mojinet.  The  alkalis  are  capable  of  decompofing  the 
muriate  of  filver,  and  feparating  the  metal.  The  filver  may  be 
difengaged  from  its  muriate  by  fufion  with  three  parts  of  black 
flux. 

Mr.  Berthollct  has  taught  us  the  following  procefs,  to  forna 
the  moft  dreadful  and  the  molt  allonifhing  fulminating  powder 
we  have  yet  been  acquainted  with.  Take  fine  filver  of  cupella- 
tion  ;  diflblve  it  in  nitrick  acid ;  precipitate  this  folution  by  lime-» 
water  ;  decant  the  water,  and  expofe  the  oxide  for  three  days 
to  the  air.  jNIr.  BerthoUet  is  of  opinion  that  the  prefence  of 
light  has  fome  influence  in  the  fuccefs  of  this  experiment. 

Mix  this  dried  oxide  in  ammoniack,  or  volatile  alkali,  and  It 
will  aflfume  the  form  of  a  black  powder  ;  decant  the  fluid,  and 
leave  the  powder  to  dry  in  the  open  air.  This  is  the  fulminat- 
ing filver. 

Gunpowder,  and  even  fulminating  gold  Itfelf,  cannot  be  com- 
pared with  this  new  produ6:.  The  contacSt  of  fire  is  necefiary 
to  caufe  gunpowder  to  detonate  ;  and  a  determinate  degree  of 
heat  is  required  to  caufe  fulminating  gold  to  fulminate  :  but  the.^ 
conta£l  of  a  cold  body  is  fuflicient  to  produce  the  detonation  of 
fulminating  filver.  In  a  word,  this  produ£l,  once  obtained,  caa 
no  longer  be  touched  :  no  attempts  mufl:  be  made  to  Inciofe  it 
in  a  bottle,  but  it  mufl  be  left  in  the  capfule  wherein  the  evap- 
oration was  performed. 

It  is  ufelefs  to  obferve,  that  the  fulmination  ought  not  to  be  ' 
attempted  but  with  fmall  quantities  ;  the  weight  of  a  grain,  for 
example  :  for  a  larger  mafs  would  give  rife  to  a  dangerous  deto- 
nation. The  necefiity  of  making  this  preparation  with  the  face 
covered  with  a  mafk  with  glafs-eycs,  may  be  eafily  conceived. 
It  is  prudent  to  dry  the  fulminating  filver  in  fmall  metalHck  cap- 
fules. 

The  following  experiment  will  complete  the  notion  which 
ought  to  be  formed  of  the  fulminating  property  of  this  prepara- 
ticn. 


384  Properties  of  GoM, 

Take  the  ammonlack  which  was  ufed  in  the  converfion  of  the 
oxide  of  filver  into  the  black  precipitate  which  forms  fulminat- 
ing filver  :  put  this  amrrioniack  into  a  fmall  mattrafs  of  thin 
glafs,  and  let  it  be  fubjected  to  the  dec^ree  of  ebullition  neceflary 
to  complete  the  combination.  Take  the  mattrafs  from  the  fire  ; 
and  a  rough  covering  of  cryftals  will  be  formed  on  its  internal 
furface  which  is  beneath  the  fluid.  If  one  of  thefe  cryftals  be^ 
neath  the  cold  fluid  be  touched,  an  explofion  takes  place  which 
breaks  the  mattrafs. 

The  procefs  for  obtaining  fulminating  filver  being  defcrlbed^ 
its  efl?e<5U  known,  and  the  cautions  neceirary  for  repeating  the 
experiment  being  well  afcertained,  we  fhall  fpeak  a  word  con- 
cerning the  theory  of  the  phenomenon  :  it  is  the  fame  as  that 
of  fulminating  gold,  laid  down  by  Mr.  Berthollet. — See  the  Me- 
moirs of  the  Royal  Academy  of  Sciences,  for  the  year  1785. 

In  this  operation,  the  oxigene,  which  adheres  very  flighrly  to 
the  filver,  combines  with  the  hydrogeneof  the  amiHoniack.  From 
the  combination  of  the  oxigene  and  the  hydrogene,  water  in  the 
flatc  of  vapour  is  produced.  This  water,  inllantly  vaporized, 
and  pofTefling  all  the  elafticity  and  expanfive  force  of  that  ftate, 
is  the  principal  caufe  of  the  phenomenon  ;  in  which  the  nitro- 
genej  which  is  difengaged  from  the  ammonlack,  with  its  whole 
expanfibillty,  llkewife  bears  a  principal  part. 

-  After  the  fulmination,  the  filver  is  found  reduced  or  revivi- 
fied j  that  is  to  fay,  it  has  refumed  its  metallick  ftate.  It  again 
becomes  the  fame  white,  brilliant,  and  pure  metal  which  it  was 
when  taken  out  of  the  cupel. 

The  principal  ufe  of  filver  is  in  coinage,  as  the  reprefentative 
fign  of  the  value  of  other  commodities. 

Its  metallick  brilliancy  has  caufed  it  to  be  adopted  as  an  orna- 
ment ;  its  hardnefs  and  unchangeablenefs  in  the  air,  render  it 
very  valuable. 

It  is  alloyed  with  copper^  to  form  folder  ;  whence  it  happens 
that  filver  utenfils  are  fubjedl  to  ruft  and  verdigris,  at  the  places 
where  they  are  foldered. 


CHAPTER    XIV. 

Coficerning  Gold. 

GOLD  is  the  mod  perfect,  the  mod  du£lilc,  the  moil  tena- 
cious, and  the  mod  unchangeable,  of  all  the  known  metals. 
A  cubick  foot  of  pure  gold,  calt  and  not  hamm.ered,  weigh* 
1348  pounds  5  and  its  fpeclfick  gravity  is  19.258  i.—^See  Briilon. 


OresofGoll  385 

'Gold  has  neither  fmell  nor  taftc  ;  its  colour  is  yellow,  ^nd 
'ihis  varies  according  to  the  purity  of  the  metal. 

1.  As  Gold  is  fubjed  to  very  little  alteration,  it  is  almoft  al- 
ways found  in  the  native  (late ;  and  under  this  form  it  exhibits 
the  following  varieties  : — i.  It  is  found  in  oiflahedrons  in  the 
Gold  mines  of  Boitza  in  Tranfylvania.  Thefe  oftahedrons  are 
fometimes  truncated  in  fuch  a  manner  as  to  have  the  appearance 
of  hexagonal  plates.  This  native  gold  is  alloyed  with  a  fmall 
quantity  of  filver ;  which,  according  to  Mr.  Sage,  gives  it  a 
pale  yellow  colour.  It  has  likewife  been  found  cryftallized  in 
tctrahedral  prifms,  terminated  by  four-fided  pyramids.  The 
amalgam  made  with  certain  precautions  is  likewife  capable  of 
caufing  gold  to  afiume  a  form  nearly  fimilar,  according  to 
Mr.  iSage  ;  and  gold  reduced  by  phofphorus  fometimes  exhibit^ 
octahedral  cryltals. 

Gold  likewife  cryftalllzes  by  fufion.  MefTrs.  Tillet  and  Mon- 
gez  obtained  it  in  fhort  quadrangular  pyramids. 

2.  Native  gold  fometimes  exhibits  fibres  or  filaments  of  vari- 
cus  lengths  ;  it  is  likewife  found  in  plates  diifleminated  on  a 
gangue.  The  gold  ore  of  Lagardet,  a  few  leagues  diflant  froni 
Alemont  in  Dauphiny,  is  of  this  kind.  3.  Gold  is  likewife  found 
fometimes  in  fmall  plates  or  fpangles,  difperfed  in  fand  or  earths  : 
under  this  form  it  is  found  in  the  auriferous  rivers,  fuch  as  the 
Ariege,  the  Ceze,  the  Gardon,  the  Rhone.-  Thefe  fmall  plates 
are  fometimes  one  line  in  diameter,  but  mod  commonly  too 
fmall  to  be  feen  by  the  naked  eye.  4.  Gold  is  fometimes  found 
in  irregular  mafles ;  in  which  inltance  it  is  known  by  the  name 
of  Gold  Duft.  Very  large  pieces  of  this  kind  are  found  iii 
Mexico  and  Peru. 

3.  Gold  is  fometimes  mineralized  by  fulphur,  by  the  means 
of  fire.  ^  The  auriferous  pyrites  are  frequently  found  in  Peru, 
Siberia,  Sweden,  Hungary,  &c.  To  afcertain  whether  a  pyrites 
contains  gold  or  not,  it  mufl:  be  pounded,  and  nitrick  acid  pour- 
ed upon  it  until  it  takes  nothing  more  up.  This  folution  mud 
then  be  diluted  with  much  water.  The  lighted  infoluble  parts 
may  be  carried  off  by  wafliings  ;  and  the  refidue,  upon  exami- 
nation, will  (hew  whether  it  contains  gold  or  not. 

When  the  martial  pyrites  is  decompofed,  the  gold  is  always 
difengaged  ;  and  it  is  probable  that  the  fmall  plates  of  gold  in  the 
auriferous  rivers,  are  afforded  by  a  decompofition  of  this  kind. 

Gold  is  fometimes  mineralized  by  fulphur,  with  the  affidance 
of  zinc,  as  in  the  gold  mine  of  Nagyag.  This  ore  likewife  con- 
tains lead,  antimony,  copper,  filver  and  gold. 

4.  Mr.  Sage  has  given  a  defcription  and  analyfis  cf  an  arfen- 
ical  ore  of  gold. 

3...A 


Gro«. 

X 

Grains. 
56 

% 

36 

J 86  Method  of  Worhittg  Geld  Ores. 

5.  Gold  likewife  exifts  natiiraUy  ia  vegetabks.  Beclier  ob- 
tained it.  Henckel  aiHrmed  that  they  contained  it  ;  and  Mr* 
Sage  has  refumed  this  enquiry,  and  foumi  it  according  to  the 
following  table,  which  exprefles  the  quantities  of  gold  obtained 
from  the  quintal  of  the  feveral  earths. 

O  mice  5, 
Rotted  manure  (terrcau)  o 

Earth  of  uncultivated  ground  7 

(terra  de  Bruyere)  j  ^ 

Garden  mould        -        -        -        o  j  o 

Mould  of  a  kitchen  garden  'y 
manured  with  dung  yearly  V        2  3  40 

for  iixty  years  j 

Thefe  refults  were  at  firfl:  contefted  ;  bat  at  prefent  it  ap- 
pears to  be  generally  agreed  that  gold  is  obtained,  but  in  a  lefs 
quantity.  Mr.  BerfhoUet  obtained  forty  grains  and  eight  twen- 
ty-fifths of  gold  in  the  quintal  of  allies.  Meff'rs.  Rouellc,  Dar- 
cet,  and  Deyeux  llkcwife  obtained  it. 

It  is  therefore  a  phyfical  facfl,  that  gold  exllls  in  vegetables. 
The  method  of  working  the  ores  of  gold  is  neariy  the  fame  as 
that  ufed  with  filver  ores.  When  the  gold  is  in  a  native  ftate, 
nothing  more  is  required  than  to  divide  the  ore  by  the  pound- 
ing mill,  and  afterwards  to  wafh  and  amalgamate  it.  If  the  ore 
be  mineralized,  it  is  torrefied,  pounded,  wafhed,  fufed  with  lead, 
and  afterwards  cupelled.  Eliquation  is  likcwifc  ufed  for  poor  ores. 
Thofe  perfons  who  explore  the  gold  rn  fmali  plates  diiiemi- 
nated  in  the  fand  of  certain  rivers,  are  known  in  France  by  the 
name  of  Orpailleurs,  or  Pailloteurs.  The  pailloteurs  of  the 
river  TJze,  after  having  afcertained  that  the  earth  is  fufficiently 
rich  to  be  wrought,  place  a  table  feveral  feet  in  length,  and  a- 
bout  a  foot  and  a  half  ia  width,  on  the  banks  of  the  river  with 
ledges  round  three  of  its  fides.  Pieces  of  fluff  with  a  long  nap 
are  nailed  on  to  this  board ;  and  the  fand  is  thrown  upon  it,  and 
waflied  to  carry  away  the  lighter  particles.  When  the  fluff  is  fuf- 
ficiently charged  with  the  fmall  particles  of  gold,  it  is  fhaken  in- 
to a  vefTel,  agitated  with  water  to  carry  oii'the  lightefl  fand,  and 
afterwards  amalgamated  with  mercury.*  Mr.  £11  has  given  us 
^n  ample  ax:count  of  the  procefs  ufed  in  working  the  gold  ores 


*  For  a  very  full  account  of  the  treatment  of  auriferous  fands,  the  fol- 
lowing works  may  be  confulted  : — r.  The  Memoir  of  Mr.  Reaumur  on  tlic 
Auriferous  Sands  of  France,  printed  among  thofe  of  the  Academy  for  tl>c 
year  17 18.  a.  The  Memoir  of  Mr.  Guett.ard  on  the  Aricge,  inlerted  in 
the  volume  for  1 76 1.  3.  The  Memoir  upon  the  Gold  which  is  obtained 
from  the  Ariege  in  the  county  of  Foix,  by  the  Baron  de  Dietrich.  In  th.s 
laft  work,  the  various  procefles  are  difcufled ;  and  this  celebrated  miner- 
alogifl  propofes  oth-crs  more  economical  and  advantageous. 


Method  <)f  Workmg  Gold  Ores,  3<5  y 

ill  Spanifli  Soulli- America.  A  fuffjcient  quantity  of  water  is 
procured  to  wJtfli  them.  A  ftream  is  made  to  carry  off  the 
earth,  aiKi  every  lighter  fuoltance.  Negro  flaves,  difperfed  on 
the  banks,  throv*^  ki  feefh  earth  ;  while  otl^rs,  itanding  lu.  the 
iMTOok,  work  it  about  with  their  fbet  and  hands.  Care  is  taken 
to  lay  pieces  of  wood  acrofs  the  curren^t  of  the  water,  to  retain 
the  Hghttsr  particles  of  the  metal.  This  work  is  continued  for 
a  month,  and  even  for  years  together.  When  it  is  propofed  to 
terminate  it,  the  water  is  turned  off ;  and  then,  in  prefence  of 
the  mailer,  the  workmen  take  up  the  iaml  with  wooden  vefiels, 
in  the  form  of  {ii allow  funnels,  of  ©ne  foot  in  diameter,  at  the 
bottom  of  which  is  an  aperture  of  one  inch  in  width.  Thisdifli 
is  filled  with  fjand  ;  anci  by  a  circular  motion  the  lighter  fubflan- 
ces  arc  caufcd  to  fiowofF,  whik  the  heavier  fettle  to  the  bot- 
tom. The  platina  is  afterwards  feparated  grain  by  grain, 
with  the  blade  of  a  knife,  U;pon  a  fmooth  board.  The  reft  is 
amalgamated,  firft  by  working  with  the  hands,  and  afterwards 
with  a  wooden  peft{j  in  mortars  of  guaiacum  wood  :  after  which 
the  mercury  is   feparated  from  tlie  gold  by  fire. 

The  Baron  de  Born  has  reduced  the  method  of  working  all 
the  ores  of  filyer  and  gold  to  one  fingle  procefs.  The  account 
which  he  has  given  of  this  procefs  in  his  work,  may  be  reduced 
to  the  following  operations  : 

1.  The  mineral  is  pounded,  divided,  and  fifted. 

2.  It  is  properly  roafted. 

3.  it  is  mixed  with  muriate  of  foda,  water,  and  mercury  ; 
and  agitation  is  ufcd  to  facilitate  the  amalgamation. 

4.  The  mercury  is  exprelled  from  the  amalgam. 

5.  The  expreiTed  mercury  is  expofed  to -diltillation. 

6.  The  filver  is  refined  by  tlic  cupel. 

Thefe  operations  were  (ir^  execAited  at  Schemnitz  in  Hunga- 
ry, aiid  afterwards  at  Joackimftal  in  Bohemia,  in  the  prefence 
of  the  greateft  mincralogiits  in  Europe,  fent  hither  by  the  vari- 
oAis  fovereigns  of  Europe. 

The  muriate  of  foda  is  ufed  to  decompofe  the  fulphates  pro- 
duced by  the  calcinations. 

To  determine  the  linenefs  of  gold  with  accuracy,  the  pureft 
is  fuppofed  to  be  twenty-four  carats,  and  thefe  carats  are  divid- 
ed into  thirty-fecond  parts;  the  carat  is  always  reprefented  by  a 
grain  poids  de  marc. 

The  law  diredis  the  operations  to  be  performed  upon  twenty- 
four  grains  of  gold,  tolerates  twelve,  and  prohibits  fix,  on  ac- 
count of  the  dilliculty  of  appreciating  the  divifions  which  refult 
frgm  tlieiie  fmall  quantities. 


28S  EffeB  of  H^at  on  Qold. 

In  the  parting  affay,  very  pure  filver  mufl:  be  made  ufe  of. 
This  is  mixed  with  the  gold  in  the  proportion  of  four  to  one, 
which  has  occafioned  the  name  of  Qu^artation  to  be  given  to  the 
procefs,  Mr.  Sage  has  found  that  two  parts  and  a  half  of  filver 
to  one  of  gold  form  the  mixture  moft  proper  for  making  the 
cornet  of  affay.  The  two  metals  are  wrapped  up  in  a  thin  piece 
of  lead  four  times  the  weight  of  the  gold,  and  this  mixture  is 
put  into  the  cupel  when  it  is  very  hot.  The  refult  of  the  cupel- 
latlon  is  a  button  containing  fine  gold  and  fine  filver.  This  is 
flattened,  lamellated,  and  rolled  up.  into  a  fpiral ;  put  into  a  fmall 
mattrafiS,  and  fix  gros  or  drams  of  pure  nitrick  acid,  at  thirty^ 
two  degrees  of  concentration,  are  poured  on  it.  As  foon  as  the 
m.attrafs  is  heated,  the  metal  becomes  brown,  the  filver  is  diffolv-; 
ed,  and  much  red  vapours  are  difengaged.  At  the  end  of  fifteen 
minutes  the  folution  is  decanted  5  and  an  ounce  of  very  pure 
acid,  rather  more  concentrated,  is  poured  on,  to  carry  away  the 
laft  portions  of  filver.  This  folution  is  decanted,  after  a  digef- 
tion  of  fifteen  or  twenty  minutes;  at  which  period  warm  water 
is  added,  and  the  cornet  is  waftied  until  the  water  comes  off 
taftelefs.  It  is  then  dried  in  a  crucible,  weighed,  and  the  fine- 
nefs  judged  by  the  diminution  of  its  weight. 

fcrchindlers  and  Schutler  have  maintained  that  gold  always  re- 
tains a  fmall  quantity  of  filver,  which  they  have  called  the  Inter- 
halt,  or  Surplus.  Mr.  Sage  found  a  fixty-fourth  part  of  a  grain 
in  the  belt  conduced  aflay. 

In  order  to  feparate  the  filver  which  is  diffblved  in  the  nitrick 
acid,  this  folution  is  diluted  with  a  confiderable  quantity  of  wa- 
ter, and  flat  pieces  of  copper  are  plunged  in  it  ;  which  precip- 
itate the  filver,  as  we  haveobferved  in  treating  of  the  folution  of 
filver. 

Gold,  expofed  to  fire,  becomes  red-hot  before  it  melts. 
When  melted  it  fuffers  no  alteration."*^  Kunckel  and  Boyle  kept 
it  iri  a  glafs-houfe  furnace  for  feveral  months  without  change. 

Flomberg  has  neverthelefs  obferved  that  this  metal,  expofed  to 
the  focus  of  the  lens  of  Tfchirnaus,  fmoked,  was  volatilized,  and 
even  vitrified  in  part.  Mr.  Macquer  has  verified  this  obfervation 
by  the  mirror  of  Mr,  De  Trudaine  ;  he  obferved  the  gold  fume 
become  volatilized,  and  covered  with  a  dull  pellicle,  which  con- 
ftituted  a  violet-coloured  oxide  towards  the  middle. 

Gold  is  not  attached  by  the  fulphurick  acid. 

The  nitrick  acid  appears  to  have  a  real  adlion  upon  it.  Brandt 
is  the  firll  who  announced  the   folution   of  gold  by    this  acid. 

♦  Gold  when  fiifed  by  a  ilrong  heat  is  of  a  beautiful  green  colour  during 
tbe  fufioHo  •  ' 


Citrous  Solution  of   Gold.  ^tf 

The  experiments  were  made  in  the  prefence  of  the  King  of 
Sweden,  and  verified  by  his  Academy.  Meflrs.  SchefFer  and 
Bergmann  have  confirmed  the  aflertion  of  Brandt  \  and  Mr. 
Sage  afterwards  pubiiihed  a  feries  of  experiments,  on  this  fub- 
jedt.  I  am  convinced,  from  my  own  experiments,  feveral 
times  repeated,  that  the  purefl  nitrick  acid  attacked  gold  in  the 
cold,  and  diflblved  a  fixty-fourth  part  of  a  grain.  When  very 
pure  nitrick  acid  is  boiled  upon  gold  equally  pure,  the  folution 
may  be  afcertained  in  three  ways — i.  By  the  diminution  of  the 
weight  of  the  metal.  2.  By  evaporation  of  the  acid  ;  in  which 
cafe  a  purple  fpot  remains  at  the  bottom  of  the  evaporatory  vef- 
£el.  3.  By  the  parting  operation,  by  means  of  a  plate  of  filver 
put  into  the  liquor.  In  this  cafe  black  flocks  are  in  a  fhort 
time  difengaged,  which  confift  of  the  gold  itfelf.  Thefe  phe- 
nomena appear  to  announce  a  true  folution  ;  and  not  a  fimpla 
divifion  or  fufpenfion,  as  was  fuppofed. 

The  quantity  of  gold  difiblved  appeared  to  me  to  vary  accord- 
ing to  the  ftrength  of  the  acid,  the  time  of  the  ebullition,  and 
the  thicknefs  of  the  metallick  body. 

The  nitro-muriatick  acid,  and  the  oxigcnated  muriatick  acid, 
^re  the;  true  folvents  of  gold.  Thefe  acids  attack  it  with  greater 
energy  in  proportion  as  they  are  more  concentrated,  and  as  the 
furface  of  the  gold  is  larger.  The  folution  may  iikewife  be  ac- 
celerated by  he^t. 

This  folution  has  a  yellow  colour,  is  cauftick,  and  tinges  the 
|kin  of  a  purple  colour.  If  it  be  properly  concentrated,  it  af- 
fords yellow  cryftals,  refembling  topazes,  which  afi^icl  the  form 
of  truncated  odahedrons.  Thefe  cryltals  are  a  true  muriate  of 
gold,  according  to  Meifrs.  Bergmann,  Sage,  &c.  If  the  folution 
of  gold  be  diftilled,  a  red  liquor  is  obtained,  which  confifts  of 
the  muriatick  acid,  coloured  by  a  fmall  quantity  of  gold  which 
U  has  carried  over.  This  fluid  was  dillinguifhed  by  the  adepts 
under  the  name  of  Red  I^ion. 

Gold  may  be  precipitated  from  its  folution  of  feveral  colours, 
Recording  to  the  nature  of  the  fubftances  employed  to  make  the 
precipitation.  Gold  is  precipitated  by  lime  and  magnefia  in  a 
yellow  powder  in  which  the  gold  exids  nearly  in  the  metallick 
(late  ;  a  flight  degree  of  heat  only  being  neceflfary  to  convert  it 
to  that  ftate. 

The  alkalis  Iikewife  precipitate  gold  in  the  form  of  a  yellowifii 
powder  5  and  the  precipitate  is  foluble  in  the  fulphurick,  nitrick, 
and  muriatick  acids.  Thefe  concentrated  folutions  fulilr  the 
gold  to  precipitate  ;  cryftals  have  not  been  obtained  from  them* 

Jf  amraoniack  be  poured  on  a  ycUowifli  folution  of  gold,  the 
colour  difappears  j  but,  at  the  end  of  a  certain  time,  fmall  flocks 


^30  Fulftjinatm^  Gold, 

anre  difetigsaged,  which  become  more  and  more  yeJKrvr,  and  gra^, 
uaily  fubfide  to  the  bottom  of  the  veBel.  This  precipitate,  being 
dried  in  the  (liade,  is  known  by  the  name  of  Fulminating  Gold  ; 
a  denomination  which  it  has  obtained  on  account  of  its  proper* 
%y  of  tletonating,  when  gently  heated. 

Ammoniack  is  abfolutely  neceflary  to  produce  this  efFedl:. 

The  experiments  of  feveral  chemifts  have  taught  us — i .  That, 
by  gently  heating  fulminating  geld  in  copper  tubes,  one  extrem- 
ity of  which  was  plunged  in  the  pneumato-chemical  apparatus 
by  the  aiTilta-nce  of  a  cyphon,  alkaline  gas  is  obtained,  and  the 
precipitate  is  deprived  oi  its  fulminating  property  :  this  fine  ex- 
periment was  made  by  Mr.  Berthollet.  2.  Bergmann  has  ob- 
ferved  that,  byexpbfing  fulminating  gold  to  a  gentle  heat,  inca- 
pable  of  caufmg  it  to  fulminate,  it  becomes  deprived  of  that 
property.  3.  When  the  gold  is  made  to  fulminate,  in  tubes 
whofe  extremities  are  inferted  under  a  veflel  filled  with  mercury, 
the' product  is  iiitrogene  gas,  and  fome  drops  of  water.  4.  By 
triturating  fulminating  gold  with  oily  fubftances,  it  is  deprived 
of  its  property  of  fulminating. 

From  thefe  eftablillied  fa£ls,  it  is  evident  that  fulminating 
gold  is  a  mixture  of  ammoniack  and  oxide  of  gold.  When  this 
mixture  is  heated,  tlie  oxigene  is  difcngaged  at  the  fame  time 
with  the  hydrogene  of  the  alkali.  Thefe  two  gafes  take  fire  hy 
fimple  heat,  detonate,  and  produce  water  ;  the  nitrogene  ga« 
then  remaining  alone.  From  thefe  principles  it  ought  to  fol- 
low, that  oily  lubll^nces  which  combine  with  the  oxigene,  acide 
which  feize  the  alkali,  or  a  gentle  and  long  continued  heat,  which 
volatilizes  the  two  principles  without  inflaming  them,  ought  to 
deprive  this  preparation  of  its  property  of  fulminating. 

The  niirous  fulphur  which  Mr.  Baum^  fuppofed  to  be  form* 
cd,  in  his  explanation  of  this  phenomenon,  does  not  exift  ;  for 
.the  folution  .of  the  oxide  of  gold  by  the  fulphurick  acid,  when 
precipitated  by  ammoniack,  affords  a  fulminating  precipitate. 

Gold  is  precipitated  from  its  folution  by  feveral  metals,  fuch 
as  lead,  iron,  filver,  copper,  bifmuth,  mercury,  zinc,  and  tin. 
This  laft  precipitates  it  inllantly  in  the  form  of  a  powder,  dif- 
trngmfio^d  by  the  name  of  the  Purple  Powder  of  Caflius.  This 
precipitate  is  much  ufed  in  porcelain  manufa£i:ories.  Some  ve- 
ry good  obfervations  on  this  preparation  may  be  feen  in  the  Die* 
ticnary  of  Macquer. 

Gold  may  iikewife  be  precipitated  from  its  folution  by  ether  ; 
this  liquor  feizes  the  gold  in  a  moment,  and  fometimes  inltantly 
revivifies  it.  I  have  feen  the  gold  form  a  flratum  at  the  furfacc 
of  the  hquor,  and  the  two  fiuids  no  longer  contained  a  particle. 


Hahitiufer  of  Ga/d*  jgi 

■  The  fulphures.  of  alkali  diflblve  gold  completely.  Nothing 
more  is  neceflary  for  this  purpole,  thfin  quickly  to  fufe  a  mixtiiie 
©f  equal  parts  of  fulphur  and  pot-a(h  with  one  eighth  of  the  to- 
tal weight  of  the  gold  in  leaves.  This  fubftance  may  then  ht 
poured  out,  pulverized,  and  diflblved  in  hot  water.  The  foiifc* 
tion  has  a  yellowifli  green  colour.  Stahl  afSrma  that  Mofes 
dSiJblved  the  golden  caif  by  a  firaibr  procefs  ;  and  that,  thoiigh 
riie  beverage  mud  have  Iven  of  a  difagreeable  tafte,  this  cir- 
eumftance  was  an  ackhtioni^l  reafon  for  preferring  the  method^ 
in  order  that  the  Ifraelitea  might  longer  retaia  their  difgiift  for 
idolatry. 

Gold  unites  with  moft  of  the  metals. 

Arfcnick  renders  it  brittle,  as  well  as  bifmuth,  nickel,  and 
antimony.  All  thefe  femi-metals  render  it  whire  andeager. 
.  Gold  unites  very  well  with  tin  and  lead.  Thefe  two  metal* 
deprive  it  all  of  its  dudility. 

.  Iron  forms  a  very  hard  alloy  with  gold,  which  may  be  employ- 
ed to  much  greater  advantage  than  pure  gold. 

Copper  renders  it  more  fufible,  and  communicates  a  reddifh 
colour  to  it.     This  alloy  forms  money,  gold  plate,  and  toys, 
.    Silver  renders  it  very  pale.      This  alloy  forms  the  green  gold 
of  goldfmiths. 

Gold  is  employed  in  a  variety  of  purpofes.  It  is  entitled,  by 
the  firil  raak  which  it  holds  among  metals,  to  the  moft  noble 
lifes. 

As  Its  colour  is  agreeable  to  the  eye,  and  is  not  fubje<^  to 
tamifti,  it  is  ufed  as  ornaments,  or  as  toys ;  for  which  purpofc 
k  is  wrought  into  a  thoufand  forms. 

For  fome  purpofes  it  is  drawn  into  very  fine  wire,  and  ufed 
in  embroidery.  For  other  purpofes  it  is  extended  into  leaves  fo 
extremely  thin,  that  the  llighteft  breath  of  wind  carries  them 
away  :  in  this  form  it  is  applied  upon  wooden  articles  by  means 
of  fize. 

For  other  purpofes  it  is  reduced  into  a  very  fine  powder  ; 
in  which  cafe  it  is  called  Ground  Gold,  Shell  Gold,  Gold  in 
Rags,  &c. 

The  ground  gold  is  prepared  by  levigating  the  clippings  of 
gold  leaf  with  honey,  wafliing  them  with  water,  and  drying  the\ 
particles  with  fubfide-     * 

Shell  gold  confids  of  ground  gold  mixed  with  a  mucilagi- 
nous water. 

In  order  to  make  the  gold  in  rags,  pieces  of  linen  are  fteeped 
in  a  folution  of  gold,  afterwards  dried  and  then  burned.  When 
i<. is  required  to  ufc  them,  a  wet  cork  is   dipped  in  wood  alhes,- 


3pt  ChctraBers  of  Alcheml/ls. 

and  rubbed  upon  fuch  articles  of  filver  as  arc  intended   t6  b^ 
gilded. 

For  fome  purpofes  it  is  amalgamated  with  mercury.  Thi^ 
amalgam  is  applied  upon  copper,  the  furface  being  previoufly< 
well  cleared.  It  muft  be  fpread  very  even,  and  the  mercury 
driven  ofF  by  heat.     This  forms  the  or  moulu, 

A  coating  of  gilders  wax  is  laid  over  the  gold  thus  applied. 
This  is  made  with  red  bole,  verdigris,  alurri,  and  fulphate  of 
iron,  incorporated  and  fufed  with  yellow  wax.  The  piece  is 
heated  a  fecond  time,  to  burn  off  the  wax. 

Gold  was  formerly  ufed  in  medicine.  This  remedy  was  much 
in  falhion  in  the  fifteenth  century.  Its  goodnefs  has  at  all  times 
been  proportioned  to  the  dearnefs  of  the  drug.  Bernard  de  Pa- 
lifTy  exclaimed  Itrongly  againft  the  apothecaries  of  his  time^ 
who  demanded  ducat  gold  from  the  fick  to  put  into  ther  medi- 
cines, under  the  pretence  that  the  purer  the  gold  the  more  fpee- 
dy  would  be  the  refloration  of  the  health  of  the  patient. 

As  this  metal  is  highly  valued,  the  rage  of  forming  it  conftii 
tuted  a  known  fedf,  under  the  name  of  Alchemifts,  which 
may  be  divided  into  two  clafles.  The  one  very  ignorant,  fre- 
quently unprincipled,  and  mod  commonly  uniting  both  quali- 
ties, fufFered  themfelves  to  be  impofed  on  by  certain  phenome.i 
na,  fuch  as  the  increafe  of  weight  of  metals  by  calcination,  the 
precipitation  of  one  metal  by  another,  and  the  yellow  colour 
which  fome  bodies,  and  certain  preparations  affe^l.  They 
grounded  their  notions  on  certain  vague  principles  concerning 
the  formation  of  bodies,  their  common  origin,  their  feeds,  &c. 

It  is  this  fe£l  which  has  caufed  alchemy  to  be  defined,  ar's 
fine  arUy  cujus  principium  est  meniiri,  medium^  lahorare^  terttum 
mendicare.  Thefe  alchemifiis,  after  having  been  themfelves  the 
dupes  for  a  confiderable  time,  always  endeavoured  tO  impofe  on 
others  *,  and  there  are  a  thoufand  tricks  and  impofitions  related 
of  this  clafs  of  men,  which  deferves  only  tobe  defpifed  and  pitied; 

There  is  another  clafs  of  alchemifts  which  do  not  deferve  to 
be  made  the  objeft  of  publick  derifiort  and  contempt.  This  is 
formed  of  celebrated  men,  who,  grounding  their  ideas  on  the 
received  principles,  have  dircfted  their  refcarches  tovvards  this 
objedt.  This  clafs  of  men  is  valuable  on  account  df  their  gen- 
ius, probity  and  conduct.  They  have* formed  a  language,  Iield 
fcarcely  any  communication  biit  with  each  other,  and  have  at 
all  times  diilinguilhed  themfelves  by  their  auitere  manners,  and 
their  fubmiffion  to  Providence.  The  celebrated  Becher  is  a 
name  which  alone  fuffices  to  render  this  fedl  refpedable.  The 
following  paffage,  extracted  from  Becher,  exhibits  an  idea  of 
their  language,  and  manner  of  proceeding  in  this  Itudy. 


Df  Plaiind.  3^5 

«<  Fac  ergo  ex  luna  ct  fole  merurios,  quos  cUm  primo  cnte 
fdlphuris  pr3ecipita,  praecipitatum  philofophoruni  igrie  atteriua, 
Cxalta,  et  cum  fale  boracis  philofophorum  liquefac  ct  fige  donee 
fine  fumo  fluat.  Qux,  licet  breviter  di£la  fmt,  longo  tamen  la- 
bore  acquiruntur  fet  irinere,  ex  arenofo  namque  terreftri  Arabico 
ttiari,  in  marc  rubrum  aqueumi  et  ex  hoc  iii  bituminofum 
ardens  mare  mortuum  itinerandum  eft,  non  fine  fcopulo* 
rum  et  voraginum  peHcUlo,  nos,  Deo  fint  laudes,  jam  appuli- 
mus  ad  portum.  Becher,  Phyf.  Sub.  i.  f.  v.  cap.  iii.  p.  461.  in 
8vo.  And  elfeijoherey  "Conclude  enim,  pro  thefi  firmiflima, 
afinus  eft  qui  contra  alehymiam  loquitur,  fed  ftultus  et  nebulo 
qui  illam  pra£tic^  venalem  ex  ponit.'* 

The  enlightened  alchemifts  have  enriched  chemifliry  with 
moft  of  the  products  which  were  known  before  the  late  revolu- 
tion. Their  knowledge  and  their  indefatigable  ardour  put  them 
in  the  fituation  of  profitirtg  by  all  the  interefting  fadts  which 
oiFered  themfelves. 

God  forbid  that  I  fhoukl  induce  any  perfdn  to  enter  iiito  thi» 
path.  I  would  ufe  every  effort  to  prevent  any  one  from  engag- 
ing in  this  refearch,  fo  full  of  difappointment,  and  fo  dangerous 
to  attach  the  mind  to  it.  But  I  am  of  opinion  that  the  alche- 
mifts have  been  too  lightly  treated ;  and  that  this  feft,  whick 
on  many  accounts  is  wotthy  of  commendation,  has  not  received 
the  efteem  and  gratitude  it  is  entitled  to. 

In  addition  to  thefe  reafons,  I  muft  obfcrve  that  chemical 
phenomena  become  fo  wonderful  ;  the  torch  of  analyfis  has  en* 
lightened  us  to  fuch  an  extent :  we  now  decompofe  and  repro- 
duce fo  many  fubftances,  which  ten  years  ago  were  confidcred 
with  equal  probability  as  indecompofable  as  gold  is  now  thought 
to  be  ;  that  no  chemift  can  take  upon  him  to  affirm  that  we 
may  not  arrive  at  the  art  of  imitating  nature  in  the  formation 
of  metals. 


CHAI'TER    XV. 
Concerning  Plaiina. 

We  were  unacquainted  with  platina  until  the  year  1748.  It, 
is  to  Don  Antonio  tJlloTi,  who  accompanied  the  French  Acadc- 
mecians  in  their  famous  voyage  to  Peru,  to  determine  the  figure 
of  the  earth,  that  we  are  indebted  for  our  firft  notions  of  thift' 
metal. 

Charles  Wood,  who  had  hi mfelf  brought  this  metal  from  Ja- 
maica, made  experiments  upon  it,  which  are  related  in  the  Ph«- 
lofophical  tran  fact  ions  for  the  year  1749  and  175Q. 
3.0B 


394^  Purification:,  ^c.  of  Platina, 

Since  that  time,  all  the  chemifts  in  Europe  procvMreiJ  this  mCf- 

al.  Meflrs.  Scheffer  in  Sweden,  Lewis  in  England,,  Margraffiii' 
FrufTia,  Macquer,  Baume,  De  Buffbn,  De  Milly,  Dc  Lifle,  Dc 
Morveau,  have  fucceffively  made  refearches  on  this  fubftance  j? 
and  we  are  indebted  for  great  p'art  of  our-  prefent  knowledge  of 
this  metal  to  the  Baron  de  Sicltengen; 

Platina  has  hitherto  been  found  only  in  the  metallick  ftate. 
Its  form  is  that  of  fmall  grains  or  flattened  plates,  of  a  liyid 
white  colour,  intermediate  between  that  of  filver  and  iron  :  it  ts 
from  this,  colour  that  it  derived  its  name  of  Platina,  or  Little 
Silver.  If  the  grains  of  platina  be  carefully  examined,  it  is  found 
that  fome  of  them  are  rounded,  and  others  ajigular,    .  ,    - 

It  has  been  found  among  the  auriferous  fands  of  Sottth- 
America,  near  the  mountains  of  the  diftri£ls  of  Novita  and  Cy- 
tara.  Thefe  two  metals  are  almoft:  conftanrly  accompanied  by 
a  ferruginous  fand  obedient  to  the  magnet.  The  platina  of 
commerce  ufually  contains  a  fmall  quantity  of  mercury,  arifing- 
from  the  amalgamation  which  the  ore  has  undergone  in  extra^- 
ing  the  gold.  When  it  is  required  to  have  platina  in  a  very  pure 
(late,  it  muft  be  expofed  to  heat,  to  drive  off  the  mercury,  and 
magnetieal  parts,  and  the  iron,  muft  be  forted  out  with  the  mag- 
net. Platina  itfelf  is  ftightly  attradled  by  the  magnet.  M.  L. 
affirms,  in  a  Memcir  read  to  the  Academy  of  Sciences  at  Parifr^ 
in  the  year  1785,  that  the  lighter  pieces  of  Platina  only  are  at- 
tra6l^  by  the  magnet,  and  that  they  ceafe  to  be  a6led  on  when: 
they  exceed  a  certain  fize.  The  largeft  piece  of  platina  which 
has  been  feen,  is  of  the  fize  of  a  pigeon's  egg.  It  muft  be  in  tha 
pofleffion  of  the  Royal  Society  at  Bifca. 

.  M.  L.  affirms  that  platina  is  malleable  in  its  natural  ftatc ;. 
and  he  pafled  it  thrcvigh  the  fiatting  mill  in  the  prefence  of 
-Meftrs.  Tillet  and  Darcet. 

^  Platina  undergoes  no  alteration  by  expofure  to  the  air  ;  and' 
.  fire  alone  does  not  CYen  appear  to  pofiefs  the  power  of  changing 
it.  Meffi-s.  Macquer  and  , Baume  kept  it  feveral  days  in  a  glafs- 
houfe  furnace,  without  its  grains  having  fuffered  any  other 
change  than  that  they  were  ftightly  agglutinated.  It  has  nevcr- 
.  thelefs  been  afcertaincd  that  heat,  kept  up  for  a  long  time,  tar- 
nifhes  its  furface,  and  increafes  its  weight.  Margraif  formerly 
.^made  this  obfervation. 

^.  Platina  expofed  to  the  focus  of  the  burning  mirror  of  Mr. 
De.  Trudaine,  fumes  and  melts.  This  metal  may  be  hammer- 
ed liiic  gold  and  filver.  It  may  Hkewife  be  fufed  iipon  char- 
coal, by  the  affiftance  of  oxigenous  gas.  .  This  fubftance  refifts 
the  aclion  of  .the  acids,  fuch  as  the  fulphurick,  the'nitrick,  and 
the  muristick  acidi  ;■    it  is  foluble  only  ,  in  the  oxigenatcd; 


M 


iCharaffers  of  Tlailna.  29S 

«iuriatick  and  the  nitro-muriatick  acids.  One  pound  of 
tiie  latter,  digefted  on  an  ounce  of  platlna,  firft  aflumcs  a  yel- 
low colour,  then  an  orange  colour,  and  laftly  a  very  obfcure 
brown.  This  folution  tinges  animal  fubftances  brown;  it 
fpontaneoufly  depofites  fmall  irregular  fawn  coloured  cryftals  ; 
but  if  it  be  concentrated,  larger  cryftals  are  obtained,  fometimes 
of  an  oftahedral  form,  as  Bergmann  has  obferved.  The  muri- 
ate of  platin'a  is  fcarcely  cauftick,  though  (liarp  ;  it  fufes  in  the 
iire,  gives  out  its  acid,  and  leaves  an  obfcure  grey  oxide. 
*  Tfe  fulphuricic  acid,  poured  on  this  folution,  forms  a  precip- 
itafe  of  a  darjc  colouir  *,  the  precipitate  oCcafioned  by  the  'mun- 
Sitick  acid,  is  yellowilh. 

The  alkalis  precipitate  platina  from  its  folution  ;  but  if  it  be 
gradually  precipitated  by  pot-afh,  the  precipitate  is  difToIvedt  by 
the  alkali  in  proportion  as  it  is  formed.  *  ---^^ 

A  folution  of  the  muriate  of  ammoniack,  poured  into  a  folu* 
<tIon  of  platina,  forms  an  orange-coloured  precipitate,  which  h 
•a^truefaline  fubftance,  totally  foluble  in  water.  This  precipi- 
tate has  been  fufed  by  Mr.  De  Liile  in  a  common  fire  (of  a  fur-- 
liace).  The  refult  of  the  fufion  is  platina,  (till  altered  by  fomc 
portion  of  faline' matter  •,  for  it  does  not  acquire  dudility  but 
b  y  expofure  to  a  much  ftronger  heat. 

The  property  which  the  muriate  of  ammoniack  poflefTes  of 
'precipitating  platina,  affords  a  very  fimple  method  of  afcertain- 
ing  the  mixture  of  this  metal  with  gold  :  fo  that  the  fear  of  this 
alloy,  which  had  alarmed  the  Spanifti  miniftry  fo  much  as  to 
occafioa  them  to  forbid  its  being  wrought,  does  not  at  prefent 
^xift,  as  we  poflefs  a  fimple  method  of  afcertalning  the  fraud  : 
"and  it  is  much  to  be  wifhed  that  this  very  precious  metal  fhould 
be  reftorcd  to  the  arts,  to  which  it  cannot  but  be  vjery  ufeful, 
by  its  brilliancy,  its  hardnefs,  and  its  unchangeable  nature. 

The  procefs  of  Mr.  De  Lifle  to  fufe  platina,  was  publifhed 
1774.  Mr.  Achard  publifhed  a  fimpler  method,  nearly  at  tkc 
fame  fime  :  it  confifts  in  taking  two  gros  of  platina,  two  grds 
6f  the  white  oxide  of  arfenick,  two  gros  of  the  acidulous  tarrritc 
of  pot-afti,  and  putting  thcni  into  a  crucible  well  luted.  This 
is  to  be  exposed  for  an  hour  to  a  violent  fire,  which  fufes  the 
platina  ;  but  it  is  brittle,  and  whiter  than  ordinary  platina.  It 
is  then  to  be  expofed  to  a  coniiderable  heat  under  a  muffle  ;  by 
which  means  all  the  arfenick  which  was  combined  with  the  pla- 
tina is  diflipated,  and  this  metal  left  in  a  ftate  of  purity.  Vef- 
fels  of  platina  may  be  formed,  by  filling  clay  moulds  with  the 
alloy  of  platina  and  arfenick  ;  and  expofing  the  mould  in  the 
muffle,  to  diilipate  the  femi- metal. 


m.^ 


3p6  Methods  of  Fuftng  Platlna, 

Mr.  Be  MorVeau  fubftltuted  the  arfeniate  of  pot-afh  to  ad^ 
vantage,  inftead  of  arfenick  ;  and  he  had  already  fufed  plating 
with  his  vitreous  flusf,  made  pf  pounded  glafs,  borax,  and  char^ 
coal. 

Mr.  Pelletier  fufed  platina,  by  mixing  it  with  phofphorick 
glafs  and  charcoal  The  phofphorus  then  unites  with  the  platl- 
na ;  and  the  phofphurc  of  platina  is  exppfed  to  a  degree  of  he^t 
fufTicient  to  volatilize  the  phofphorus. 

Mr.  Baume  advifes  to  fufe  platina  with  a  flight  addition  of 
lead,  bifmuth,  antimony,  or  arfenick  ;  and  to  keep  the  alloy  ia 
the  fire  a  long  time,  to  diflipate  the  metals  which  have  facilitat- 
ed the  fufiOn, 

Platina  may  likewife  be  fufed  with  a  metal  foluble  in  an  acid ; 
the  mixture  being  pulverized,  the  alloyed  met  al  may  be  diffolv- 
cd  ;  and  the  powder  of  platina  may  then  be  fufed  ^yith  the  flux 
of  De  Morveau. 

Inflead  of  ufing  a  foluble  metal,  a  calcinable  metal  may  be 
employed,  and  treated  as  before. 

The  cubick  foot  of  crude  platina  weighs  1092  livres  i  ounce 
7  gros  17  grains  j  platina  purified  and  fufed  weighs  1365  li- 
vres  ;  and  purified  platina  forged  weighs  1423.8.7.64. 

Mofl  of  the  neutral  falts  h^ve  no  perceptible  a<iion  upon  pla- 
tina. The  refults  of  feveral  curious  experipients  may  be  feen 
in  the  Memoirs  of  MargrafF. 

The  nitrate  of  pot-afh  alters  platina,  according  to  the  experi- 
ments of  Lewis  and  Margraff.  Dr.  Lewis  by  heating  a  mix- 
ture of  one  part  of  platina  and  two  parts  of  this  nitrate,  during 
three  times  twenty-four  hours,  obferved  that  the  metal  aflumed 
^  rufly  colour.  By  difFufing  the  mixture  in  water,  the  alkali 
was  difTolved  ;  and  the  platina,  deprived  of  all  the  foluble  mat- 
ter, is  diminifhed  one  third,  The  powder  taken  up  by  the  alka- 
li is  the  oxide  of  iron,  mixed  with  the  oxide  of  plafina. 

Thefe  experiments,  as  likewife  the  property  which*platina 
pofTefles  of  being  a£led  on  by  the  magnet,  prove  that  it  contains 
^ron  •,  and  Mr.  de  BufFon  has  concluded  that  this  metal  is  a  nat- 
ural alloy  of  gold  and  iron.  But  it  has  been  objected  that  the 
artificial  alloy  of  thefe  two  metals,  made  in  every  polTible  pro- 
portion, never  refembles  platina  ;  that  this  metal  departs  mor^ 
from  the  properties  of  gold  in  proportion  as  it  is  deprived  of  iron  ; 
fo  that  it  is  confidered  as  a  truly  peculiar  metal. 

This  metal  is  capable  of  being  alloyed  with  mof);  of  the  known 
pictals. 

Scheffer  firft  affirmed  that  arfenick  rendered  it  fufible. 

Meffrs.  Achard  and  De  Morveau  have  availed  thcmfelv^s  pf 
^is  property  to  fufe  it,  and  compofe  velfels. 


Allocs  of  Flatina,  ^{^f 

Platina  eafjly  unites  with  bifmuth.  The  refult  is  eager,  very 
brittle,  difficuhly  cupelled  j  and  the  refult  is  a  mafs  which  ha§ 
Jittle  duftility. 

Antimony  like  wife  facilitates  the  fuTion  of  platina.  The  aU 
ley  is  brittle  j  part  of  the  antimony  may  be  difcngaged-by  fire  ; 
but  a  fufi^ciept  quantity  remains  in  combination  to  deprive  the 
platina  of  its  weight  and  dudility. 

Zinc  renders  this  metal  more  fufible.  The  alloy  is  rcry  hard  \ 
great  part  of  the  zinc  may  be  volatilized  by  fire  ;  but  the  pla- 
^na  always  retains  a  fmali  quantity. 

This  metal  unites  eafily  with  tin.  This  alloy  is  very  fufible^ 
and  flows  clear  j  it  is  eager,  and  very  brittle  :  but  when  the  tiit 
is  in  a  large  proportion,  the  alloy  is  du<SliIe  ;  its  grain  is  coarfe, 
and  it  becomes  yellow  by  expofure  to  the  air. 

Lead  unites  very  well  with  platina.  A  ftronger  heat  is  requir- 
ed to  fufe  this  than  the  foregoing  alloy.  It  is  not  dudlile  ;  is  no 
longer  capable  of  being  abforbed  by  the  cupel,  the  abforption 
only  taking  place  when  the  lead  is  in  excefs  ;  but  the  platina  re- 
mains always  united  to  a  confiderable  portion  of  the  metal. 
Neverthelefs  Meflrs.  Macquer  and  Baume  cupelled  one  ouncd 
of  platina  and  twenty  ounces  of  lead,  by  cxpofing  this  alloy,  for 
fifty  hours,  in  the  hotted  part  of  the  porcelain  furnace  at  Seves, 
Mr.  De  Morveau  had  the  fame  refult  in  Mr.  Macquer's  wind- 
furnace  :  the  operation  lafted  between  eleven  and  twelve  hours. 
Mr.  Baume  obferved  that  the  platina  obtained  by  this  procefs 
poffefles  the  power  of  being  forged  and  foldered  completely, 
without  the  afliftance  of  any  other  metal,  which  renders  it  a 
moft  valuable  acquifition  in  the  arts. 

Dr.  Lewis  could  not  unite  forged  iron  with  platina ;  but  hav- 
ing melted  crude  iron  with  this  metaj,  there  refulted  an  alloy  fo 
hard  that  the  file  could  not  touch  it ;  it  was  ductile  in  the  cold, 
but  broke  fhort  when  hot. 

Copper  and  platina  alloyed  together  form  a  very  hard  metal, 
which  is  ducftile,  while  the  copper  predominates  in  the  propor- 
tion of  three  or  four  to  orve  ;  it  takes  a  fine  poliih>  and  was  not 
tarnilhed  during  the  fpace  of  ten  years. 

Platina,  alloyed  with  filver,  deprives  it  of  Its  duftility,  increaf. 
es  its  hardnefs,  and  tarnifhes  its  colour.  Thefe  two  metals  may 
be  feparated  by  fufion  and  repofe,  Lewis  obferved  that  the  fil- 
ver which  isfufed  with  platina  is  thrown  up  againft  the  fides  of 
the  crucible  with  a  kind  of  explofion  :  this  phenomenon  appears 
to  be  owing  to  the  filver,  as  Mr.  Darcet  found  it  break  porcelain 
balls  in  which  it  was  inclofed,  an(i  out  of  which  it  was  proje(51ed 
by  the  J^^lion  of  the  (ire. 


k 


-  Gold  U  not  <:apal>le  pf  being  alloyed  with  platina  but  by^he 
inpft  violent  heat :  the  colour  of  the  gold  is  pr6_digiqufly'altered, 
llnd  the  alloy  poiTelTes  confiderable  du^iility.  *^ 

Wj^  know  enough  of  the  properties  of  this  metal  to  prefumc 
thaMt  will  prove  of  the  greateft  ufc  in  the  arts.  Its  almoft 
albiblt^te  infii&Klity, .  and  its  iinchan^eablenefs,  render  it  of  eit- 
feenie  value  to  form  ehenfiical  yi^f^^%  fuch  as  crucibles  and  the 
li]ce.  The  property  of  foMering  or  welding  without  mixture, 
renders  it  preferable  to  gold  or  filver*  "  .     ,  .    '' >■' 

'-  its  deniity  and  opacity  render  it  likewife  of  great  value  for 
thc:C(^ftru6lipn  of  optipal  inilruments  ;  and  the  abbe  Rochoji 
l\as  cpnilfuifted  a  mirror  whofe  effciti:  greatly  furpaflfes  that  of 
the  mirrors  before  made  of  fteel  and  other  metals. '  This  metal 
■unites  two  qualities  never  before  found  in  one  and  the  fame  fub* 
ftance.  Like  other  metallick  mirrors,  it  refiedlsbu.tpnefinglc 
'ima^  V  at  the  fame  time  that  it  is  as  unchangeable  af  the  rt\if- 
•jiSjjcsof  ^als.  '       '  "       '''""  '"  "■        ''*    ' ■'■'\ 

CHAPTER    XVr. 
Confemitig  Wungfi^niindWvl^ai^. 

i     WE  are  acquainted  with  two  minerals  which  may  be  diftiQ. 

fuifhed  by  the  generick  title  of  Tungfteri  ;  the  one  white,  and 
nown  by  the  nam?  of  Tungften;  or  the  Heavy  Stone  of  the 
Swedes  ;  -the  other  known  by  the  narne  of  Wolfram  by  minex* 
alogifts.    We  fliall  examine  each  fcparately. 


mm^M. .  I. 

Concerning  Tungften. 

^^ull{lgAn  isafubfl^pce  of  a;i  pp^igue  white  colour,  Very  heavy, 
;Wjd  of  a  mocierate  degree  of  hardnefs:  its  cryftals  are  o.£lahe- 
drons.  Its  fpecifick  gravity  is  6.06165,  according  to  Briflbn  ; 
from  4,59  to  5,8,  according  to  Kirwan.  The  cubick  foot 
weighs  424  livres  xo  ounces  3  gros  60  grains. 

When  e^^pofed  without  addition  to  the  flame  of  the  blow-pipe, 
\%  decrepitates  without  melting.  With  foda  it  is  divided  with' a 
flight  effervjejfccnce  •,  is  partly  foluble  in  the  native  phofphate,  or 
xnicrocofmick  fait ;  and.^ffiDrds  a  fine  blue  colour  without  the 
ieaft  appearance  of  red  in  tlie  refraifled  light,  as  happens  wiich 
cobalt.    It  is  foluble  in  borax  without  efferyercence. 


ExtraSiidn  of  i^t  AM  of  tungsten,  y^ 

Sergmann  affirms  thai  by  fouring  tKe  mUnatic|  *ci3  tt']^ 
liulverized  tungilen  the  powder,  immeaiatctjr  tfflumcs  a  fine 
ffcrlght  yellow  colour.  To  this  charadler  Schpele  ^Sds  tR^  ol 
feccpming  bluifh  when  boiled  in  the  fulphuritt  acid.  ,  , 

This  fubftance  has  a  fparry  apipearancc,  and  was  long ,  toSi 
mnded  with  the  white  tin  ore.  It  is  touni  at  Bitffecrg,  it  ftidi-r 
larhittan,  ajt  Marienburg,  at  Altembu'rg  in  Saxony,  and  at  Sau* 
€rg  near  Ehrehfriederidorft.  , 

Mr.  Rafpe,  in  Creli's  Annals  for  June  1785,  gav;^  an  3c<foiirit 
h)f  two  mines  of  tungftcn  in  the  province  of  CorAwail, ,  froin 
hich  thoufands  of  tons,  might  be  extra£led.     I'his^hilofophrf 
)tained  the  metal  in  the  proportion  of  about  thirty 'llx  hvrcs 
.the  quintal.     He  adds  that  this  metil  contains  little  iron  |.  that 
[it  is  very  fixed,  arid  refractory  in  tKe  fire  \    and  that  it  atfes  ba 
flafs  like  the hardeft  fteel.  ,  .,  ,.\,    .  ,     ■ 

;.  pronltedt  arranges  the  tung^en  aihong  the  iron  ores ;  ari3 
Refines  it  to  be  ferrum  cateijorme  terra  quadam  incognlia  intim^ 
imixtum.  .^-^       •      ,  ^^  ,.. 

Scheele  has  affirmed  that  it  rs  a  fatt  refulting  from  tne  comii 
|l)ination  of  calcareous  earth  with  a  peculiar  acid  ;    which  acxdi 
[Combined  with  lime-water,  regenerates  tungften. 
,   Bergmann  cbitfiders  the  acid  eairth  of  ti:tngflen  as  a  metiUi^ 
acid. 

Several  prdcSfTcis  aire  4t  pifcfent  ktiOwn  fdir  extr^iri|  ^t  Sel4 
of  tungften. 

I.  Any  defired  qtrantity  of  this  mineral  is  to  be  puiveriiSl^ 
smd  fufed  with  four  times  its  weight  of  carbonate  of  pot-a'ili| 
and  poured  out  upon  a  plate  of  raetai.  The  itiafs  is  thrift  to  b^ 
AifToIved  in  twelve  parts  of  boiling  water.  A  white  pbv^def  feg^ 
aiatcs  during  the  folution,  and  falls  to  the  bottom  of  the  ve&ei; 
This  precipitate  is  a  true  carbonate  of  lime,  mixed  with  a  fmall 
quantity  of  quartz,  and  a  portion  of  undecompofcd  tungften. 
The  carbonate  of  lime  may  be  taken  up  from  the  precipitate  \if 
fvitriek  acid  •,  and  the  remaining  tungften. being  mjxed  wit}>  the 
former  proportion  of  carbonate  ofpot-a^,  is  to  be  fufed,  diiTolv- 
ed,  and  by  a  repetition  of  thefe  operations  will  at  length  be  to- 
tally decompofed.  The  w^ater  in  which  the  fufed  xnafTes  were 
walhcd,  holds  in  folution  a  fait  formed  by  the  tungftick  acid  and 
the  alkali  made  ufe  qf.  If  this  folution  be  faturated  with  ni^ 
ttick  acid,  it  feizes  the  alkali ;  the  folution  becomes  thick  ;  and 
t  white  powder  falls  down,  which  is  the  tungftick  acid. 

a.  Scheele  the  author  of  this  firil  proccfs,  propofes  a  fecond', 
which  confi.lts  in  digefting  three  parts  of  weak  nitrick  acid  up6a 
One  of  pulverifed  tungften..  This  powder  becomes  yellow  ;  th$ 
ftuid  is  thcux  decanted,  and  two  parts  of  ammoniack  arc  poured . 


469  ^cld  of  Tungsiefii 

upon  the  yellow  powder.  The  powder  then  becomes  white  5 
^nd  in  this  way  the  repeated  actions  of  the  acid  and  the  alkali 
are  applied  until  the  tungfteri  is  diflblved.  Out  of  four  fcruples^ 
treated  by  Scheele  in  this  manner,  there  were  three  grains  of 
infoluble  matter,  which  was  a  true  quartz.  By  adding  the  pruf- 
fiate  of  pot-afli  to  the  nitrick  acid  made  life  of,  he  obtained  two 
grains  of  Pruffian  blue ;  pot-afh  precipitated  three  of  chalk ; 
and  the  ammoniack  uniting  to  the  nitrick  acid,  precipitated  an 
acid  powder,   which  is  the  true  tungftick  acid. 

In  this  expefimant  the  nitrick  acid  feizes  the  lime,  and  uncov- 
ers the  tungftick  acid,  which  is  feized  by  the  alkali. 

The  muriatick  acid  may  be  fabftituted  to  advantage  inftead  of 
the  nitrick  acid,  arid  even  gives  it  a  yellower  colour. 

Scheele  and  Bergmann  confidered  this  acid  powder  as  the  true 
tungftick  acid  in  a  ftate  <jf  purity.  MefTrs.  Delhuyars  have  af- 
ferted  that  this  acid  was  mixed  with  thb  acid  made  ofe  of  inf 
obtaining  it,  and  alfo  \Vith  the  alkali  ^  they  affert  that  the  yellow 
jpowder  which  is  Uncovered  by  the  digeftioti  of  the  nitrick  acid, 
is  the  true  acid  oxide  of  tungften  without  mixture. 

The  white  powdef  which  is  obtained  by  decompofing  the?  al- 
kaline folution  of  turigftcn  by  an  acid,  is  acid  to  the  tafte,  red- 
dens the  tin£lure  of  turnfole,  precipitates  the  fulphure  of  alkali 
of  a  green  colour,  and  is  folublc  in  twenty  parts  of  boiling  water. 

Properties  of  the  white  po^'der  oh'     Properties  of  the  yello<w  matter  oJr 

tainedhy  decompofing  the  folution         iainedby  fire  or  by  acids, 

of  the  ore  oftungjien  by  an  acid. 

I.  An  acid  tafte,  reddening  the  i.  Infipid,  'reddening  the  tin<5!urc 
lindlure  of  tarnfole.  of  turnfole. 

a.  Expofed  to  flame  urged  by  a.  Treated  with  the  blow-pipe, 
the  blow-pipe,  it  paffes  to  a  brown  it  preferves  its  yeWow  colour  in  the 
and  black  colour,  without  afford-  the  external  fl^me  ;  but  fwelis  up  and 
ing  either  fumes  Or  ligns  of  fulion.     and  becomes  black,  without  fufing, 

in  interiour  blue  flame. 

3^  It  is  foluble  in  twenty  parts  3^  It  is.infoluble,  but  capable  of  be- 
ef boiling  water.  coming  fo  divided  as  to  pafs  through 

the  filters. 

4.  It  becomes  yellow  by  boiling         4.  The  three  mineral  acids  have  no 
icthe  nitrick  and  muriatick  acids,     aclion  upon  it. 
and  bluifh  in  the  fulphurick  acid. 

From  this  comparifon  it  appears  that  the  acid  is  purer  in  the 
yellow  powder  than  in  the  white  ;  and  the  filine  combinations 
of  thefe  twx>  fubftances  have  confirmed  MefTrs.  Delhuyars  in 
their  opinion. 

The  ydlow  acid,  combined  with  pot-afh,  either  in  the  dry  or 
humid  way,  forms  a  fait  with  excefs  of  alkali.  If  a  few  drops 
of  nitrick  acid,  be  poured  on  this  fait,  a  white  precipitate  is  in- 
ftantly  formed,  whi^  h  is  redifjolved  by  agitadon.     When  all  ths 


Properties  of  JFoI/rdm.  4b  t 

alkali  is  faturated,  the  folution  is  bitter ;  if  more  acid  be  poured 
in,  the  precipitate  which  falls  down  is  no  longer  foluble.  This 
precipitate,  when  well  edulcorated,  is  exactly  of  the  fame  na- 
ture as  the  white  powder  we  have  fpoken  Of.  The  experiments 
of  MefTrs.  Delhuyars,  and  of  Mr.  De  Morveau,  prove  very  clear- 
ly that  this  white  powder  contains  the  acid  of  tungften,  a  por- 
tion of  the  pot-afli  with  which  it  was  before  combined,  and  a 
fmall  quantity  of  the  precipitating  acid. 

It  is  therefore  well  proved  that  the  yellow  matter  is  the  pure 
oxide,  and  the  true  tungftick  acid.  It  is  likewife  very  certairt 
that  this  acid  exifts  ready  formed  in  the  metal  5  and  that  its  ox- 
igene  is  afforded  neither  by  the  decompofition  of  another  acid^ 
nor  the  fixation  of  the  oxigenous  gas  of  the  atmofphere ;  it  ap- 
pears to  exift  in  the  mineral,  and  to  conflitute  a  kind  of  fait  of 
many  principles. 

'  The  pure  tungftick  acid  difTolves  ammoniack  5  but  the  refult 
is  always  with  excefs  of  alkali.  This  folution  affords  by  evapo- 
ration fmall  cryflals,  of  a  penetrating  bitter  tafle,  foluble  in  wa- 
ter, and  then  reddening  blue  paper.  The  alkali  is  eafily  fepa- 
rated  ;  and  thefe  cryftals  return  by  calcination  to  the  flate  of 
yellow  powder,  entirely  fimilar  to  that  which  entered  into  its 
compofition.  If  the  calcination  be  mkde  in  clofed  veflels,  the 
refidue  is  of  a  deep  blue  colour  ;  for  the  yellow  colour  does  not 
appear  unlefs  the  calcination  be  made  in  the  open  air. 

The  experiments  of  Mr.  De  Morveau  permitted  him  to  clafs 
the  affinities  of  this  acid  in  the  following  order,  which  is  the 
fame  as  that  of  the  arfenical  acid  :  lime,  barytes,  magnefia,  pot^ 
afh^  foda^  ammoniack,  alumine,  metallick  fubllances. 


ARTICLE    11. 

Concerning  Wolfram. 

Wolfram  is  of  a  blackifh  brown  colour,  fometimes  afFe(fling 
the  form  of  an  hexahedral  compreffed  prifm,  terminated  in  a 
dihedral  fummit.  Thefe  furfaces  are  frequently  flriated  longi- 
tudinally. Its  fracture  is  lamellated,  fohated,  and  the  leaves 
are  flat,  though  rather  confufed.  Externally  it  refembles  fchorl ; 
but  is  not  fufible,  and  is  incomparably  heavier. 

Some  mincralogifts  have  taken  it  for  an  arfenical  ore  of  tin  5 
others  for  manganefe,  mixed  with  tin  and  iron.  MefTrs.  Del- 
huyars, who  made  a  ftridt  analyfis  of  it,  found  it  to  contain 
manganefe  22,  oxide  i3f,  quartzofe  powder  2,  yellow  powdet 
or  tungftick  acid  6^, 
3...C 


4^2  Allop  of  Woljram* 

The  WQlfram  wUich  was  analyfed  by  thefe  clicmift?,  cairp 
from  the  tin  mines  of  Zinnwahfe,  '  on  the  frontiers  of  Saxony 
and  Bohemia.      Its  fpecifick  gravity  was  6.835. 

Wolfram  doss  not  m"lt  by  the  blow-pipe  without  addition,  it» 
angles  being  fcarcsly  rounded.  With  the  native  phofphate,  or 
microcofmick  fait,  it  melts  with  efFervefcence,  and  affords  a  glaf» 
of  a  hyacinth  colour. 

It  cffervefces  with  Borax,  and  forms  a  greenifli  yellow  glaft 
w  the  blue  flame.  Tliis  glafs  becomes  red  In  the  external 
flame. 

Pulverized  wolfram  upon  which  t]>c  murlatick  acid  is  boiled^ 
afllmies  a  yellow  colour  like  tungften. 

^  MeiTrs.  Delhuyars  fufed  in  a  crucible  two  gros  of  pulverized 
Ivolfram,  and  four  gros  of  pot-afh.  The  fufed  mixture  being  pouf- 
ed  out  on  a. plate  of  copper,  a  black  matter  remained  in  the 
crucible  ;  which,  when  well  edulcorated,  weighed  thirty-feven 
grains,  and  was  found  to  be  a  mixture  of  iron  and  mangancfe. 

The  mafs  which  had  been  poured  out  was  difTohTd  in  water » 
filtered,  and  faturated  with  nitrick  acid.  It  afforded  a  white 
precipitate,  abfolutely  (imilar  to  that  obtained  from  tungften  by 
a  fimilar  procefs. 

The  procefs  of  Scheele  by  the  humid  way,  fuccceds  equally 
well,  and  even  appeared  to  Meffrs.  Delhuyars  to  be  more  advan- 
tageous. They  prefer  the  difengagement,  by  mere  heat,  of  the 
ammoniack  which  holds  the  tungftick  acid  in  folution.  Qne 
hundred  grains  of  wolfram,  treated  with  the  muriatick  acid  an^ 
ammoniack,  afforded  fhem  fixty-five  grains  of  a  yellow  pow4eTf 
which  is  the  pure  acid. 

This  yeHow  acid  powder  unites  with  moft  of  the  metals. 
Meffrs.  Delhuyars  rehte  the  following  fadts  : 

I.  One  hundred  grains  of  goldleafj  and  fifty  grains  of  the 
yellow  matter,  urged  by  a  violent  heat  for  three  quarters  of  an 
hour,  in  a  crucible  fined  v/Ith  charcoal,  afforded  a  yellow  button, 
•which  crumbled  in  pieces  between  the  fingers,  and  internally 
exhibited  grains  of  gold,  with  others  of  a  grey  colour,  Thi» 
button  weighed  one  hundred  and  thirty-nine  grains;  and  wag 
cupelled  with  lead,  though  with  diffhculty. 
'  2.  Similar  proportions  of  platina  and  the  yellow  matter,  treat- 
ed in  the  fame  way  (for  an  hour  and  a  quarter,)  afforded  a  fria- 
tie  button,  in  which  graitrs  of  platina  were  ditLinguifhable,  of  a 
\yhiter  colour  than  ordinary.  It  v,'eighed  one  hundred  and  forty 
grairis. 

-  3.  With  filver,  the  yellow  matter  formed  a  button  of  a  white 
jGrreyifh  colour,  rather  fpungy,  which  extended  itfeif  eafily  by  a 
few  ftrokes  of  the  hammer  \  but  on  continuing  them,  it  fjjlit  in 


Aihys   of  WUfmm^  403 

pieces.  This  button  weighed  one  hundred  and  forty-two  grains, 
and  the  mixture  was  perfect. 

.  4.  With  copper,  it  afforded  a  button  of  a  coppery  red  colour, 
incUning  to  grey,  which  was  fpungy,  and  confiderably  du£ii!c. 
it  weighed  one  hundred  and  thirty-three  grains. 

5.  With  trud-e  or  ca(t  iron,  of  a  white  quality,  it  afforded  a. 
perfed  button,  whofe  frackure  was  conipatl,  and  of  a  greyiih 
white  colciir.  It  was  hard,  brittle,  and  weighed  one  hundred 
and  thirty-fevcn  grains. 

6.  With  lead,  it  ailbrded  a  button  of  an  obfcure  grey  colour, 
with  very  little  brilhancy,  fpungy,  very  d-udtile,  and  fplitting  \\y 
to  leaves  when  hammered.  It  weighed  one  hundred  and  tweiv- 
ty-feven  grains. 

7.  The  button  formed  with  tin  v/as  of  a  lighter  grey  than  the 
preceding,  very-fpungy,  fomewliat  du61ile,  and  weighed  one 
Iiundred  and  thirty-eight  grains. 

"8.  The  button  of  antimony  was  of  a  bright  grey,  rather 
fpungy,  brittle,  and  eafily  broken  ;  it  weighed  one  hundred  ^nA 
eight  grains. 

9.  That  of  bifmuth  prefented  a  fra^ure  which,  when  feen  iii 
one  direction,  was  of  a  grey  colour,  and  metallick  luftre  5  but 
in  another  direction  it  appeared  like  an  earth  without  any  luftre  : 
but  in  both  cafes  an  inhnity  of  pores  were  feen  over  the  whole 
mafs.     It  weighed  fixty-eight  grains. 

10.  The  button  formed  with  zinc  wa«  of  a  black  greyifli  col- 
our, and  an  earthy  afpe(ft,  very  fpungy,  and  brittle  :  it  weighed 
forty-two  grains. 

1 1.  With  common  manganefe  it  afforded  a  button  of  a  bluifh 
grey  colour,  and  earihy  alpecl:.  Its  internal  part,  examined  with 
a  lens,  rcfembled  an  impure  fcoria  of  iron  j  it  weighed  one  hun- 
dred and  fcven  grains.* 

Thefe  experunents  confirm  the  fufpicion  of  the  celebrated 
Bergmann  :  who,  from  the  I'pecifick  gravity  of  this  fubltance, 
and  its  property  of  colouring  the  native  phofphate  and  borate  of 
foda,  concluded  that  it  was  of  a  metailick  nature. 

The  change  of  colour  which  accompanies  its  reduftion,  its 
increafe  of  weight  by  calcination,  its  metallick  afpett,  and  its 
uniting  with  other  metals,  are  inconteliable  proofs  of  its  metal- 
lick  nature.  The  yellow  matter  mufl  therefore  be  confidered 
as  a  metallick  oxide  3  and  the  button  obtained  by  expoiing  this 
oxid-jto  a  flrong  iire,  with  powder  of  charcoal,   is  a  true  metal. 

*  Jn  Cullen's  Tranflation  of  the  Chemical  Analyfis  of  Wolfram,  printed 
in  London  in  1785,  I  hnd  the  word  bro'mi  in  every  place  where  M.Chap- 
talhas  uf.d  :he  word^'^/v/Jor  ^'/-ry.  Not  having  the  original,  1  cannojt 
fpeak  with  cjrtaiDty  ;   b;:t  from  circuniftances,  conclude  this  lait  to  bi: 

rjgiit.    T 


:i 


a 


404  Concerning    Molyhdena, 

Meflrs.  Delhuyars  having  put  one  hundred  grains  of  the  yeU 
low  matter  into  a  lined  crucible  well  clofed,  and  expofed  it  to  a 
ftrong  heat  for  an  hour  and  a  half,  found  upon  breaking  the 
crucible,  when  cold,  a  button  which  was  reduced  to  powder  be- 
tween the  fingers  :  its  colour  was  grey.  On  examining  it  with 
the  magnifier,  an  aflemblage  of  metallick  globules  were  feen, 
among  which  fome  were  of  the  bignefs  of  a  pin*s  head,  and 
when  broken  exhibited  a  metallick  fra£lure  refembling  fteel.  It 
weighed  fixty  grains  and  of  courfe  there  was  a  diminution  of 
forty.  Its  fpecifick  gravity  was  17.6.  Having  calcined  a  part 
of  it,  it  became  yellow  with  ^^4  increafe  of  weight.  The  ni- 
trick  and  the  nitro-muriatick  acid  changed  it  into  a  yellow  pow- 
der. The  fulphurick  and  muriatick  acids  diminifhed  its  weight, 
and  their  folution  let  fall  Pruilian  blue.  The  metallick  grains 
always  remained  after  the  a<^ion  of  thefe  acids.  This  metal 
Ijiews  various  properties,  which  diftinguifti  it  from  all  others 
Icnown.  I.  Its  fpecifick  gravity  is  17.6.  2.  It  forms  peculiar 
glafs  with  the  feveral  fluxes.  3.  It  is  almoil  abfoiutely  infu- 
iible,  much  lefs  fufible  than  manganefe.  4.  Its  oxide  is  of 
yellow  colour.  5.  It  forms  peculiar  alloys  with  the  known  met- 
als. 6.  It  is  infoluble  in  the  fulphurick,  muriatick,  nitrick,  and 
i^itrormuriatick  acids  ;  and  thefe  two  laft  convert  it  into  an  ox- 
ide. 7.  The  oxide  combines  with  alkalis.  8.  The  oxide  is  in- 
foluble in  the  fulphurick,  nitrick  and  muriatick  acids,  and  af- 
f^mes  a  blue  colour  with  this  laft. 

Wolfram  ought  to  be  confidercd  as  an  ore,  in  which  this  met.j 
^  is  combined  with  iron  and  manganefe,  as  Meflrs.  Delhuyars 
Ii^ve  proved. 


CHAPTER    XVIL 

Concerning  Molybdena* 

TWO  fubftances  have  long  been  confounded  together  under 
the  name  of  Black  Lead  Ore,  Mineral  Lead,  Plumbago,  and  Mo- 
lybdena,  which  the  more  accurate  analyfis  of  the  celebrated 
Scheeie  has  proved  to  be  of  a  very  different  nature. 

Molybdena  cannot  be  confounded  with  the  mineral  of  which 
black  lead  pencils  are  made,  which  is  cajled  Plumbago.  The 
charadleriflick  differences  are  fufficiently  evident  to  leave  no 
dpubt  on  this  fubjedl:. 

Molybdena  is  compofed  of  fcaly  particles,  cither  large  or 
fmall,  and  llightly  adherent  to  each  otl^er.     It  is  foft  and  fat  to 


^ 


Molyhdena  and  its  Oxide,  j^oh 

the  touch,  foils  the  fingers,  and  makes  a  trace  of  an  afli  grey 
colour.  Its  afped  is  bluifh,  nearly  refembling  that  of  lead. 
The  mark  it  makes  on  paper  has  an  argentine  brilliancy  ;  where-» 
as  thofe  of  plumbago  arc  of  a  darker  and  lefs  (hining  colour ; 
its  powder  is  bluifh  ;  by  calcination  it  emits  a  fmell  of  fulphur, 
and.  leaves  a  whitifh  earth.  The  nitrick  and  the  arfenical  acids 
are  the  only  acicfl^'l\'hich  attack  it  effediually  j  it  is  foluble  in  fo- 
da  with  effervefcence  before  the  blow-pipe  ;  it  caufes  the  ni-' 
trate  of  pot-afl>  to  detonate,  and  leaves  a  reddifti  refidue  ;  whea 
expofed  to  the  flame  of  the  blow-pipe  in  the  fpoon,  it  emits  %: 
white  fume. 

Plumbago  is  lefs  fat,  lefs  granulated,  and  compofed  of  fmall 
brilliant  particles.  It  lofes  in  the  fire  ^y-^  of  its  weight,  and  the 
refidue  is  an  oxide  of  iron. 

Molybdena  has  been  found  in  Iceland,  in  Sweden,  in  Saxony^ 
in  Spain,  in  France,  &c.  ;  that  of  Iceland  is  found  in  plates,  in 
a  red  feld  fpar  mixed  with  quartz. 

Mr.  Hafl'enfratz  gave  Mr.  Peiletier  famples  of  molybdena  fim-. 
ilar  to  thofe  of  Iceland,  which  he  had  colleded  in  the  mine 
named  Grande  Montagne  de  Chateau  Lambert,  near  Tillot, where 
a  copper  mine  was  formerly  wrought. 

William  Bowles  appears  to  have  found  molybdena  near  the 
village  of  Real  de  Monailerio  :  it  is  in  banks  of  gritftone,  fomc- 
times  mixed  with  granite. 

The  molybdena  of  Nordberg  in  Sweden  is  accompanied  with 
iron  that  obeys  the  magnet. 

The  molybdena  of  Altemberg  in  Saxony  nearly  refembles- 
that  of  Nordberg. 

Mr.  Peiletier  analyfed  all  thefe  fpecics ;  and  his  work  may., 
be  confulted  in  the  Journal  de  Phyfique  for  1785  ;  but  the  ex- 
periments we  (hail  here  relate  were  made  with  that  of  Altem-« 
berg. 

Molybdena,  expofed  to  heat  on  a  teft,  becomes  covered,  af- 
ter the  fpace  of  an  hour,  with  a  white  oxide  j  which,  when  coU- 
l^ded  by  a  procefs  fimilar  to  that  uied  with  the  fublimed  oxido 
of  antimony,  has  all  the  appearances  of  this  lafl^fubftancc.  The 
whole  of  the  molybdena  may  by  this  means  be  converted  into 
o^ide.  We  are  indebted  to  Mr.  Peiletier  for  this  fine  experi* 
ment,  which  had  efcaped  Scheele. 

Molybdena  is  indcftruclible  in  clofe  vefTels,  and  prodigloufly 
refradlory,  according  to  the  experiment  of  Mr.  Peiletier,  made 
with  balls  of  porcelain  expofed  to  the  mod  intenfe  heat. 

Molybdena  treated  with  the  black  flux  was  not  reduced,  nor 
even  deprived  of  its  fulphur. 


4^  Mol^hdetia  ahj  its  Okidi*  > 

MeJybduna  fufed  u^ith  iron  affbtds  a  button,  which  refeiiiblci 
cebdlt :  it  tinites  likewife  ferfeflly  with  copper  ;  but  whcti  mii- 
«d  with  lead  and  tin,  it  renders  them  fo  refra<ftory  that  the  re- 
(ults  are 'pulverulent  and  infufible  alloys. 

The  oxide  of  molybdena  obtained  by  calcination,  or  by  th^ 
i^ion  of  the  nitrick  acid,  is  not  reducible  when  treated  with 
black  ilul,  alkali,  charcoal,  or  the  other  falihe:'  fluxes  5  ncverthe«i 
Ms  if  the  oxide  of  lead  or  copper  be  added,  the  metals  which 
rftfult  are  alloyed  with  a  portion  of  molybdena,  which  may  be 
feparated. 

The  oxide  of  molybdena  made  into  a  pafte  with  oil,  dried  by 
the  fire,  put  into  a  lined  crucible,  and  urged  by  a  violent  heat 
for  two  hours,  afforded  Mr.  Pelletier  a  fubftance  llightiy  aggluti- 
nated, which  could  be  broken  with  the  fingers;  It  was  blacky 
btit  perceptibly  of  a  merallick  afpciS!.  When  vieWfed  with  the 
ra'dgniiier,  fmall  round  grains  of  a  greyifti  metallick  colour  were 
{tcxiy  which  are  the  metal  of  molybdena.  It  is  prodigioufly  rc*^ 
fraOory  j  for  the  fire  which  Mr.  Peiietier  gave  was  ftronger  than 
that  which  Mr.  Darcet  ufed  in  the  fame  forge  to  fufe  platina  an^ 
ifcanganefe. 

^-  I.  Molybdena  is  calcinable,  and  pafles  to  the  ftate  of  a  very 
MrHite  oxide.  2.  It  detonates  with  nitre,  and  the  refidue  is  aii 
©side  of  manganefe  mixed  with  alkali.  3.  The  nitrick  acid 
converts  it  into  a  white  acid  oxide.  4.  The  alkalis  difengage  hy- 
df^gerious  gas  from  it  in  the  dry.  way,,  and  the  refidue  is  the  oxr' 
ide  of  manganefe  and  alkali.  5.  It  alloys  with  the  metals  irt 
drfJ'erent  manners.  Its  alloys. with  iron,  copper,  and  fiiver,  are' 
very  friable.  6.  When  treated  ^it a  fulphur  it  regenetates  thc' 
jtlineral  molybdena.  .:     . 

Aceordirig  to  Mr.  Krrwan.,  the  mineral  of  molybdena  co!iltain| 
fifty-fi^e  pounds  fulphur,  and  forty-five  m:etali  The  iron  is  ac* 
cidental.  .  :- 

To  reduec  the  mineral  molybdena  to  powderj  Seheele  diredbs. 
-^^t  it  be  triturated  in  a  mortar  with  a  IrHall  quantity  of  fulphate 
ctf  pot-athi  The  powder  is  afterwards  wafhed  in  hot  water,  to 
carry  off  the  faltj   and  the  molybdena  remains  pure.  .    : 

•  This  bte  is  a  true  pyrites,  which   when  treated  with  the." 
Wovir-pipc,   emits   a  white  acid  fume.       But  as  this  method 
affords  oniy   a   fmall   (quantity   of   oxide,  another  method  is 
uled    to   obtain   it.       Thirty   parts   of   nitrick  acid    are   dif-- 
tolled  on   one   of  powder  of  molybdena  ;    care  being   takeii 
to  ufe  a  large  refort,  and  to  poor  the  acid  on  at   feveral  times>r 
Having  pTcvioufly  diluted  it  with  one  fourth  of  water.     The  re- 
ceiver being  luted  on,   the  diftillation  is  performed  on  thefand-  ^ 
badi.    When  the  fluid  begins  to  boil,  a  ccnfiderable  cuantity  of 


Acid  of  Molyhdenn.  4^7 

nitrous  gas  comes  over.  The  diftillation  tfeing  continued  to  dry- 
tiefs,  there  remains  a  powder,  upon  which  an  additional  dofe  of 
nitrjck  acid  is  poured  j  and  this  management  is  repeated  until  all 
the  nitrick  acid  has  been  ufed.  At  the  end  of  the  procefd  thjsre 
remains  a  refidue  as  white  as  chalk,  which  is  to  be  walhcd  witb 
water  to  carry  ofF  a  fmall  quantity  of  fulphurick  acid,  which  is 
formed  by  the  dccompofition  of  the  nitrick  acid  upon  the  ful- 
phur.  After  this  edulcoration  there  remain  fix  gros  thirtyrfix 
grains  of  an  acid  powder,  when  the  operation  has  been  made 
with  thirty  ounces  of  nitrick  acid,  and  one  ounce  of  molybden^i 
It  is  the  molybdick  acid.  :' 

.  The  arfenical  acid  diftilled  from  the  mineral  molybdena,  like* 
\5rife  aiTords  the  molybdick  acid.  ? 

It  is  evidently  feen  that  its  formation,  like  that  of  the  apfena-^ 
cal  acid,  is  owing  only  to  the  decompofition  of  the  acid  made, 
ttfe  of,  and  the  fixation  of  their  ojcigene  on  the  metal  employedi 

This  acid  is  white,  and  leaves  a  perceptibly  acid  and  mctall^ 
ick  tafte  on  the  tongue. 

Its  fpecifick  gravity  compared  with  that  of  pure  water  is 
3.460  :   1. 000,  according  to  Bergmann. 

It  undergoes  no  alteration  in  the  air. 

It  does  not  rife  in  fublimation,  but  by  the  adidance  of  thft 
air. 

It  colours  the  native  phofphate  of  a  beautiful  green. 

If  it  be  diftilled  with  three  parts  of  fulphur,  the  mineral  mo* 
lybdena  is  regenerated.  This  acid  is  foluble  in  five  hundred 
and  feventy  times  its  weight  of  water  at  a  mean  temperature. . 
The  folution  is  very  acid  ;  decompofes  the  folutions  of  foap  ;■ 
precipitates  the  fulphures  of  alkali.  It  becomes  blue  and  con* 
fiftentby  cold. 

'.  The  concentrated  fulphurick  acid  difroly£S  a  large  quantity  of 
it.  .  The  folution  affumes  a  fine  blue  colour,  and  becomes  thicld 
by  cooling.  This  colour  difappears  by  heat,  and  returns  again: 
ai  the  fluid_cools. 

,  The  jnutiatick  acid  diflblves  a  confiderable  quantity  by  thdt 
adiftance  of.  ebullition.  If  the  folution  he  diftilled,  it  leaves  » 
refidue  of  an  obfcure  blue  colour.  By  an  incrcafe  of  heat,  v/hite^ 
fublimate  rifes  mixed  with  a  little  blue  ;  the  fuming  muriatick 
acid  pafTes  over  into  the  receiver.  This  fublimate  attrafts  hu- 
midity, and  is  nothing  but  the  molybdick  acid  volatilized  by  thl5& 
muriatick. 

rThis  folution  of  the  molybdick  acid  precipitates  Giver,  mercu^^ 
ry,  and  lead  from  their  folutions  in  the  nitrick  acid.  It  likewif<? 
precipitates  lead  from  its  folution  of  the  muriate  of  Issd,-but: 
not  Uie  other  metals. 


4^^  4cid  of  Motybdena. 

The  molybdick  acid  takes  barytes  from  the  nicrick  and  rtiuri- 
atick  acids. 

In  the  dry  way  it  deeompofes  the  nitrate  of  pot-afh,  and  "the 
muriate  of  foda  ;  and  the  acids  pafs  over  in  the  fuming  ftate. 

It  difengages  the  carbonick  acid  from  its  combinations,  and 
unites  with  the  alkalis. 

It  even  partly  deeompofes  the  fulphate  of  pot-afh  by  the  af- 
fiftance  of  a  ftrong  heat. 

It  diflblves  feveral  metals,  and  aflumes  a  blue  colour  in  pro- 
portion as  it  yields  its  oxigene  to  them. 

The  combinations  of  this  acid  with  the  alkalis  are  little  known. 
Scheele  however  has  obferved,  that  fixed  alkali  renders  this  acid 
earth  more  foluble  in  water  ;  that  the  alkali  prevented  the  acid 
from  rifing  ;  that  the  molybdite  of  pot-afti  is  precipitated  by 
cooling  in  fmall  granulated  cryftals. 

The  oxigene  adheres  but  ilightly  to  the  molybdick  bafe  :  for 
this  acid  boiled  with  the  femi-metals  does  not  fail  to  affiime  a 
blue  colour. 

Hydrogenous  gas  pafTed  through  it  is  fufficient  to  produce 
the  blue  colour. 

Molybdena,  as  Mr.  Pelletier  has  obferved,  has  great  refem-» 
blance  in  its  chemical  refults  to  antimony  ;  fmce,  like  that  femi- 
metal  it  is  capable  of  affording  by  calcination  an  argentine  ox^ 
Jde,  capable  of  vitrification. 


PART  THE  FOURTH. 
)NCERNING  VEGETABLE  SUBSTANCES. 

i 

•      tivITRODUCTION. 


r 

^m  X  HE  mineral  bodies   upon  which  we  have  hitherto 

treated,  poflefs  no  life  or  vital  principle,  properly  fpeaking  ; 
neither  do  they  exhibit  any  phenomena  dependant  upon  internal 
Organization.  The  cryftallization  afFeded  by  fubftances  of  this 
kingdom,  appears  to  be  exceedingly  different  from  the  organi- 
zation of  living  beings.  It  produces  no  advantage  to  the  indi- 
vidual ;  and  at  mod  ferves  only  to  prove  the  great  harmony  of 
nature,  which  marks  its  feveral  produdtions  with  conftant  and 
invariable  forms.  But  the  organization  of  vegetable  and  animal 
beings  difpofes  thofe  bodies  in  fuch  a  manner -as  is  refpcdtively 
the  moil  proper  to  accomplifh  the  two  final  purpofes  of  nature  5 
namely,  the  fubfiftence  and  reprodudion  of  the  individual.* 

It  cannot  be  denied  that  vegetables  are  endued  with  a  princi- 
ple of  irritability,  which  developes  in  them  both  fenfation  and 
motion  :  the  motion  is  fo  evident  in  certain  plants,  that  it  may 
be  produced  at  pleafure,  as  in  the  fenfitive  plant,  the  ftamina 
of  the  opuntia,  &c.  The  plants  which  follow  the  courfe  of  the 
fun  ;  thofe  which  in  hot-houfes  incline  towards  the  apertures 
that  admit  the  light ;  other  plants  which  contraft  and  fhut  up 
by  the  puncSlure  of  an  infecSl  j  thofe  whofe  roots  turn  out  of 
their  direct  or  original  courfe  to  plunge  themfelves  into  a  fa- 
vourable foil,  or  water — have  not  thefe  a  dregree  of  fenfation  of 
touch  which  may  be  compared  to  the  fenfibility  of  animals  ?  The 
difference  of  the  fecretions  in  various  organs,  fuppofes  a  differ- 
ence in  the  irritability  of   each  refpective  part. 

The  reprodu6llon  of  vegetables  is  effected  in  the  fame  man- 
ner as  that  of  animals  ;  and  modern  botanifts  have  fupported 
the  comparifon  between  thefc  two  fundlions  in  the  moft  happy 
and  conclufivc  manner. 

*  For  the  dcvelopcment  of  thefe  principles,  fee  La  Thefe  fur  I'Analyfe 
V,cgctal  llipportcd  at  the  Ichools  of  Montpcllier  by  my  fcfaolar  and  friend, 
M.  Riche. 

3...D 


4 1  o  V-  Gensral  Account  of 

Vegetables  are  nourifhed  with  air  in  the  fame  manner  as  in- 
fedls.  This  aliment  is  even  of  intllfpenfible  neceflity,  for  with- 
out it  the  plant  at  laft  periflies  :  though  the  air  which  this  order 
of  beings  requires,  is  neither  of  the  fame  purity  nor  of  the  fame 
kind. 

The  great  difference  which  exifts  between  vegetables  and  ani- 
mals is,  that  the  latter  in  general  are  capable  of  conveying 
themfelves  from  place  to  place,  in  fearcli  of  nouriihment  ; 
whereas  vegetables,  being  lixed  in  the  fame  place,  are  obliged 
to  take  up  in  their  own  vicinity  all  fuch  matters  as  are  capable 
of  nourifhlng  them  :  and  nature  has  provided  them  with  leaves, 
to  extrafl  from  the  atmofphere  the  air  and  water  of  which  they 
have  need  ;  while  their  roots  extend  to  a  diftance  in  the  earth 
to  take  firm  hold,  as  well  as  to  receive  other  nutritive  principles* 

If  we  attend  more  minutely  to  the  charadler  of  animals,  we 
(hall  perceive  that  nature  defcends  by  imperceptible  degrees 
from  animals  of  the  moft  complicated  organization  to  vegeta- 
bles ;  and  we  iliall  find  it  difficult  to  determine  where  one  king- 
dom terminates,  and  the  other  begins.  Chemical  analyfis  is  ca- 
pable of  marking  the  limits  between  thefe  kingdoms  in  an  im- 
perfect maraier.  For  a  long  time  it  was  pretended  that  animal 
fubftances  poffeffed  the  exclufive  property  of  affording  ammo- 
niack,  or  the  volatile  alkali ;  but  it  is  at  prefent  well  known  that 
certain  plants  likewife  afford  it.  We  may  in  ftricflnefs  confider 
a  vegetable  as  a  being  that  participates  in  the  laws  of  animal  life, 
but  in  a  lefs  degree  tlran'  the  animal  itfelf. 

The  difference  which  has  been  eflablifhed  between  the  veget- 
able and  the  mineral  kingdoms,  is  much  more  ftriking.  We 
niay  confider  this  laft  as  a  mafs  deprived  of  organization,  and  al- 
moft  in  an  elementary  ftate ;  receiving  no  modifications  or 
changes  but  by  the  impreffion  of  external  objed^s  ;  capable  of 
entering  into  combinations;,  of  changing  its  nature  ;  and  of 
re-appearing,  or  being  re-produced  with  its  original  properties, 
at  the  pleafure  of  the  chemlft.  The  other  kingdom,  on  the  con- 
trary, being  endued  with  a  particular  hfe,  which  inceffantly 
modifies  the  impreffion  of  external  objeCIs,  decompofing  them, 
and  changing  their  nature,  exhibits  to  us  a,  feries  of  fuii(fbions 
regular  throughout,  and  almoft  all  of  them  inexplicable  ::  and 
vrhen  the  chemift  has  fucceeded  in  depriving  thefe  bodies  of 
their  organization,  and  feparating  their  principles,  he  finds,  it 
beyond  his  power  to  reproduce  it  by  any  re-union  of  the  fame 
principles. 

In  the  mineral  kingdom,  we  are  juftified  in  referring  all  the, 
phenomena  to  the  a6lion  of  external  bodies  ;  and  forces  purely 
phyficar,..or  the  fimple  laws  of  affinity,  afford  deductions  fufficient 


the  Vegetable  Kingdom*  4  H 

to  account  for  all  its  metamorphofes.  In  the  vegetable  king- 
dom, on  the  contrary,  we  are  compelled  to  acknowledge  an  in- 
ternal force  which  performs  every  thing,  governs  all  the  procef- 
fes,  and  fubjecfls  to  its  defigns  thofe  agents  which  have  an  abfo- 
lute  empire  over  the  mineral  kingdom. 

The  mineral  poflefTes  no  evident  life,  no  period  which  may- 
be confidered  as  the  term  of  its  perfection  ;  becaufe  its  various 
dates  are  always  relative  to  the  purpofes  to  which  we  intend  to 
apply  it.  It  does  not  appear  either  to  grow  or  to  be  reproduced ; 
at  mod  it  changes  its  form,  but  never  by  any  internal  determi- 
nation ;  this  is  always  the  mere  phyPical  effect  of  the  action  of 
external  objects.  In  thofe  cafes  wherein  the  mineral  exhibits 
marks  of  increafe  or  vegetation,  it  is  by  the  fucceffive  applica- 
tion of  fimilar  materials  worn  and  tranfported  by  the  waters. 
In  thefe  apparent  vegetations  we  perceive  neither  elaboration  or 
defign  :  the  law  of  affinities  everprefides  in  thefe  arrangements; 
and  this  law  is  the  law  of  bodies  void  of  life. 

It  is  not  therefore  furprifing  that  the  chemical  analyfis  fhould 
have  made  lefs  progrefs  in  the  vegetable  than  in  the  mineral  king- 
dom, for  it  becomes  more  diflicuk  in  proportion  as  the  fundtions 
are  complicated  :  and  in  the  vegetable  kingdom  the  conftituent 
parts  are  more  numerous,  at  the  fame  time  that  they  are  lefs 
cafily  diftinguiftied  by  chara6l;eririick  properties  ;  and  the  meth- 
ods of  analyfis  hitherto  employed  are  all  imperfect ;  not  to  men- 
tion that  the  proceedings  of  chemifts  have  likewife  been  con- 
ducted upon  an  erroneous  principle. 

All  plants  have  hitherto  been  analyfed  either  by  fire  or  by 
menftruums.  The  firft  of  thefe  methods  is  very  uncertain  ;  for 
the  adtion  of  fire  decompofes  combined  bodies,  alters  their  prin* 
ciples,  forms  new  bodies  by  the  combination  of  thefe  feparate 
elements,  and  extracts  nearly  the  fame  principles  from  very  dif- 
ferent fubltances.  Long  experience  has  (hewn  the  hnperfcCtioii 
of  this  method.  MefTrs.  Dodart,  -Bourdelin,  Tournefort,  and 
Boulduc  have  diftilled  more  than  fourteen  hundred  plants  ;  and 
it  was  from  the  refults  of  fo  extenfive  a  work  that  Romberg  de- 
duced fufficlent  reafons  to  conclude  that  this  method  is  errone- 
ous. As  a  proof  of  his  alTertion,  he  quotes  the  analyfis  of  cab- 
bage and  hemlock,  which  allbrded  the  fame  principles  by  diliil- 
lation. 

The  method  by  menftruums  is  fomewhat  more  accurate,  be- 
caufe it  does  not  change  the  nature  of  the  products  :  it  has  been 
even  of  greater  advantage  to  medicine,  by  affording  methods  of 
feparating  the  medicinal  principle  from  certain  vegetables.  It 
has  alfo  afforded  its  afliftance  to  extra£t  other  principles  in  all 
their  purity,  which  are  ufeful  in  the  arts,  or  for  the  purpofes  of 


41 2  General  Account  ofihe  Vegetable  Kingdom. 

life  ;  and  it  has  given  us  more  inftru6lion  concerning  the  nature 
of  vegetable  principles.  But  vi^c  cannot  conhne  ourfelves  to 
this  fmgle  n^ethod  in  the  analyfis  of  plants  ;  and  a  confiderable 
fhare  of  genius  is  required  in  the  chemift,  to  vary  his  procefs 
according  to  the  nature  of  the  vegetable,  and  the  charadler  of 
the  principle  he  is  defirous  of  extra£ling. 

A  reproach  of  confiderable  vi^eight  may  be  urged  againft  moft 
of  the  chemifts  who  have  \yritten  upon  the  vegetable  analyfis  : 
it  is,  that  they  have  followed  no  order  in  their  proceedings,  nor 
attended  to  any  regular  diftribution  of  the  fadis.  They  have 
confined  themfelves  to  indicate  procefles  for  extraifling  fuch  or 
fuch  fubflances,  without  conne6ling  the  whole  with  any  fyfteni 
founded  either  on  the  methods  of  operating,  on  the  nature  of  the 
products,  or  on  the  proceedings  followed  by  nature  in  its  own 
operations,  I  confefs  that,  if  a  difquifition  on  the  vegetable 
analyfis  were  to  be  confined  to  the  procefi^es  neceflary  to  be 
known  in  extra(^ing  the  fcveral  fubflances,  the  fyftem  of  ordei: 
and  of  method  which  I  propofe  would  be  ufelefs  :  but  if  it  be  a^i 
object  to  know  the  operation  of  nature,  and  to  furvey  the  ve- 
getable kingdom  like  a  philofopher,  a  naturalift,  and  a  chemift,  it 
is  necefiary  to  infpe6l  the  operations  of  nature  herfelf  among  ve- 
getables, and  to  follow  as  much  as  poflfible  a  plan  which  {hall 
render  us  acquainted  wi^h  the  plant  under  all  thefc  points  of 
view  :  that  which  I  have  adopted  appears  to  me  to  anfwer  that 
purpofe. 

We  (hall  begin  by  exhibiting  a  curfory  account  of  the  vege- 
table ftru£ture,  in  order  that  we  may  become  better  acquainted 
with  the  connexian  between  its  organization  and  the  principles 
>  which  we  iliall  extradl. 

In  the  fecond  place  we  fhall  attend  to  the  development  and 
increafe  of  the  vegetable.  With  this  intention  we  (hall  (how 
the  various  principles  which  ferve  for  its  nourifhment  ;  and  we 
fhall  follow  their  alterations  in  the  vegetable  econoniy,  as  much 
as  we  are  enabled  to  do.  We  fliall  therefore  of  confequence 
examine  the  influence  of  the  air,  the  foil,  the  light,  ^C. 

In  the  third  place  we  {hail  examine  the  refults  of  tfxe  work  of 
organization  upon  elementary  fubflances  5  and  for  that  purpofe 
we  fhall  teach  the  method  of  diltinguifhing  the  feveral  conflitu- 
ent  principles  of  vegetables  :  taking  care  to  proceed  in  this  ex- 
amination according  to  thjit  method  which  nature  herfelf  points 
out. 

Thus  we  (hall  begin  with  the  analyfis  of  fuch  products  as  we 
can  extract,  without  deflroying  the  organization  of  the  plant, 
and  which  are  exhibited  in  a  naked  ftate  by  that  organization  ; 
fuch  as  the  mucilage,  the  gums,  the  oils,  the  refins,  the  gum  re^ 


fins,  he.  Wc  fhall  in  the  next  place  analyfe  fuch  principles  as 
jcannot  be  colIe£led  but  by  deftroying  the  organization  of  the 
plant  ;  fuch  as  the  fecula,  the  glutinous  part,  the  fugar,  the 
acids,  the  alkalis,  the  neutral  falts,  the  colouring  principles,  the 
extractive  matter,  iron,  gold  manganefe,  fulphur,  &c. 

We  {hall  likewlfe  attend  to  the  prolifick  humours  of  vegc^ 
tables  ;  that  is  to  fay,  the  examination  of  fuch  fubftances  as 
though  neceffary  to  life,  are  urged  outwards  to  anfwer  certain 
functions  ;  the  pollen  and  honey  are  of  this  kind. 

We  {hall  afterwards  examine  the  humours  which  evaporate 
and  efcape  by  tranfpiration  ;  fuch  as  oxigenous  gas,  the  aqueous 
principle,  the  aroma,  or  odorant  principle,  &c. 

And  in  the  laft  place  we  {hall  {how  the  alterations  to  which 
vegetables  are  fubjecfled  after  death.  In  order  to  proceed  with 
regularity  in  a  queftion  of  fuch  great  importance,  we  fuccellive- 
ly  examine  the  a6lion  of  heat,  of  the  air,  and  o£  water,  upon 
the  vegetable,  whether  they  aft  feparately  or  together.  This 
proceeding  will  render  us  acquainted  with  all  the  phenomena 
fcxhibited  by  vegetables  in  their  decompofition. 


E^ 


SECTION    I. 

Concerning  the  Structure  of  Vegetables. 


iVERY  vegetable  exhibits  in  its  {Irufture — i.  A  fibroii* 
hard  mechanifm,  which  fupports  all  the  other  organs,  determines 
the  direction,  and  gives  the  proper  folidity  to  the  feveral  plantt 
and  their  parts.  2.  A  cellular  tiflue,  which  accompanies  all  the 
vefTels,  envelopes  all  the  {ibres,  contorts  itfelf  in  a  thoufand 
ways,  and  every  where  forms  coverings  and  a  net  work,  which 
conne£t  all  the  parts,  and  eftablifh  an  admirable  communication 
between  them.  We  fiiall  defcribe  the  feveral  parts  of  plants 
\n  a  very  concife  manner,  and  {hall  confine  ourfelves  to  the  ex- 
planation and  defcription  of  fuch  organs  as  muft  neceflarily  be 
known  with  accuracy,  before  we  can  proceed  to  the  aiialyfis  of 
plazits. 

ARTICLE    I. 

Concerning  the  Bark. 

The  bark  is  the  external  covering  of  plants  :  its  prolongations 
or  extenfions  cover  all  the  parts  which  compofe  the  vegetable. 


414  ^^f^  ^f  Vegetables* 

We  may  diftinguifti  three  particular  tunicks,  which  may  be 
feparately  detached  and  obferved.  The  epidermis,  the  cellular 
tiffue,  and  the  cortical  coatings. 

1.  The  epidermis  is  a  thin  membrane,  formed  of  fibres,  that 
crofs  each  other  in  every  diredlion  :  its  texture  is  fometimes  fo 
thin,  that  the  direction  of  its  fibres  may  be  feen  by  holding  it 
againll  the  light.  This  membrane  is  eafily  detached  from  the 
bark  when  the  plant  is  in  a  vigorous  ftate  ;  and  when  it  is  dried 
the  feparation  may  be  efFefted  by  fteeping  it  in  water.  When 
the  epidermis  of  a  plant  is  deftroyed,  it  grows  again  ;  but  isi  then 
more  ftrongly  adherent  to  the  reft  of  the  bark,  fo  as  to  form  a 
kind  of  cicatrice. 

This  epidermis  appears  to  be  intended  by  nature  to  modify 
the  impreilions  of  external  obje£ls  upon  the  vegetable  j  to  fur- 
nifli  a  great  number  of  pores,  which  tranfmit  or  throw  off  the 
excretory  products  of  vegetation  ;  to  protedl  the  laft  or  extreme 
ramification  of  the  aerial  or  aqueous  veflels,  which  extract:  out 
of  the  air  fuch  fluids  as  are  ncceffary  for  the  increafe  of  the  veg- 
etable *,  and  to  cover  the  cellular  organ,  which  contains  the  prin- 
cipal velfels,  and  thofe  glands  in  which  the  feveral  fluids  are  di- 
gefted  and  elaborated. 

2.  The  cellular  coating  form's  the  fecond  part  of  the  bark. 
Its  texture  confifts  of  veficules  and  utricles,  fo  very  numerous, 
and  fo  clofe  together,  as  to  form  a  continued  coating.  It  is 
among  thefe  glands  that  the  work  of  digeftion  appears  to  be 
pcrlormed  ;  and  the  produ£l  of  this  elaboration  is  afterwards 
conveyed  through  the  whole  vegetable,  by  veflels  propagated 
through  all  its  parts  and  communications  \  even  with  the  med- 
ullary fubftance  or  pith,  by  conduits  that  pafs  through  the 
body  of  the  tree,  crofling  the  ligneous  ftrata.  In  this  net  work 
it  is  that  the  colouring  matter  of  vegetables  is  developed  :  the 
light  which  penetrates  the  epidermis  concurs  in  enlivening  the 
colour  :  here  likewife  it  is  that  oils  and  refins  are  formed,  by 
the  decompofition  of  water  and  the  carbonick  acid  :  and  laftly 
it  is  from  this  reticular  fubftance  that  thofe  various  products  of 
the  organization  are  thrown  off  or  excluded,  which  may  be  con- 
fidered  as  the  fseces  of  the  vegetable  digcltion. 

3.  The  coatings  which  lie  between  the  external  covering  and 
the  wood  or  body  of  the  vegetable,  and  may  be  called  the  corti- 
cal coatings,  are  formed  of  laminse  which  themfelves  confift  of 
the  re-union  of  the  common,  proper,  and  air  veflels  of  the  plant. 
The  veflels  are  not  extended  lengthwife  along  the  fteni,  but  are 
curved  in  various  directions  ;  and  leaye  openings  or  meflies  be- 
tween them,  which  are  filled  by  the  cellular  matter  itfdf.  Noth- 
ing mojrc  is  neceflfary  to  (how  the  organization,  than  to  mac^r* 


Ligneous  Suhjiances,  ^l» 

ate  thefe  coatings  in  water,  which  deflroys  the  cellular  fubftan- 
ces,  and  leaves  the  net  work  uncovered.*  The  cortical  cover- 
ings are  eafily  detached  from  each  other  ;  and  it  is  from  their 
gros  refemblance  to  the  leaves  of  a  book,  that  they  have  been 
called  liber.  In  proportion  as  thefe  coatings  approach  the  ligne* 
ous  body,  they  become  hard  ;  and  at  length  form  the  external 
fofter  part  of  the  wood,  which  workmen  call  the  fap 

The  bark  is  the  mod  eflential  part  of  the  vegetable,  by  means 
of  which  the  principal  fun£lions  of  life,  fuch  as  nutrition,  diges- 
tion, the  fecretions,  &c.  arc  performed.  All  plants,  and  partic- 
ularly  thofe  which  are  hollow  within,  and  whofe  produfts  are 
totally  changed  by  covering  them  with  a  different  bark,  prove 
evidently  that  the  digcftive  force  eminently  refides  in  this  part. 
The  ligneous  part  is  fo  far  from  being  eflential,  that  many  plants 
are  without  it ;  fuch  as  the  gramineous  and  the  arund'inaceous» 
and  all  plants  that  are  hollow  within.  GrafTes,  properly  fpeak- 
ing,  have  only  the  cortical  part.  We  often  fee  plants  internally 
rotten,  but  kept  in  vigour  by  the  good  ftate  of  their  bark. 


ARTICLE    II. 

Concerning  the  Ligneous  Texture. 

Beneath  the  bark  there  is  a  folid  fabflance,  which  forms  the 
trunk  of  trees,  and  appears  to  be  ufually  compofed  of  concen- 
trick  layers.  The  interiour  coatings  or  rings  are  harder  thaa 
the  exteriour ;  they  are  older,  and  of  a  more  firm  and  clofc 
grain.  The  hardeft  of  tliefe  form  the  wood,  properly  fo  called, 
while  the  fofter  external  rings  conftitute  the  fap.  We  may  con- 
fider  wood  as  being  formed  of  fibres,  more  or  lefs  longitudinal, 
conne£^ed  together  by  a  cellular  tiflue,  interfperfed  with  vefides 
communicating  with  each  other  •,  which  diminifli  gradually  ta- 
wards  the  centre,  where  they  form  the  pith.  The  pith  is  found 
only  in  young  branches  or  plants,  and  difappears  in  plants  of  a 
certain  age. 

The  veficular  tifTue  bears  a  great  analogy  with  the  glandular 
and  lymphatick' veflels  of  the  human  body  :  in  both,  the  confor- 
mation and  ufes  are  the  fame.  In  the  early  age  of  plants  and 
animals,  the  organs  have  a  confiderable  expaiifion,  becaufe  the 
inrccafe  of  the  individual  is  very  rapid  at  that  period.      But,  as 

*  This  is  moft  particularly  fcen  in  the  arhe  a  ddntelh,  when  the  plant 
has  been  macerated  in  watei. 


4i6  Si  future  of  Vegetables, 

age  advances,  the  vefTels  become  obliterated  in  both  kingdoms  i 
and  it  is  obferved  that,  in  the  white  woods  and  fungi,  which  a- 
bound  with  the  veficular  fubftance^  the  growth  is  alfo  very 
rapid. 


ARTICLE      III. 

Concerning  \\\t  Vefiels. 

THE  various  humours  of  vegetables  are  contained  in  certain 
appropriated  vcflels,  in  which  they  enjoy  a  degree  of  motion  that 
has  been  compared  to  the  circulation  in  animals.  It  differs  front 
it,  however  ;  becaufe  thefe  humours  are  not  continually  kept  in 
equilibrio  in  the  vcflels  by  an  inherent  force,  but  receive  in  a 
more  evident  manner  the  impreflion  of  external  agents.  Light 
and  heat  are  the  two  great  caufes  which  determine  and  modify 
the  motion  of  the  fluids  and  vegetables.  Thefe  agents  caufe  the 
fap  to  rife  into  the  various  parts,  where  it  is  elaborated  In  a  mari- 
ner correfpondent  to  the  fundlions  of  each  ;  but  it  is  not  obferv- 
ed that  it  returns  :  fo  that  the  accefhon  or  flux  of  the  humours 
in  vegetables  is  proved,  but  the  reflux  does  not  appear  to  be  per- 
ceptible. 

Three  kinds  of  veflels  may  be  difllnguifhcd  in  vegetables :  the 
common,  or  fap  veflels  ;  the  proper  vefl^els  ;  and  the  air  veflfels, 
9)X  tracheal. 

I  ►  The  fap  veflels  convey  the  fap,  or  general  humour,  from 
which  all  the  others  are  derived.  This  liquor  may  be  compared 
to  the  blood  in  animals.  Thefe  vefl^els  are  refervoirs  from  which 
the  feveral  organs  extract  the  different  juices,  and  elaborate 
them  in  a  proper  manner. 

The  fap  velfels  chiefly  occupy  the  middle  of  plants  and  trees. 
They  rife  perpendicularly,  though  with  deflexions  fideways,  fo 
as  to  communicate  with  all  the  parts  of  the  vegetable.  They 
convey  the  fap  into  the  utricules  j  whence  it  is  taken  by  the 
proper  veflels,  in  order  tliat  it  may  be  duly  elaborated. 

2.  Each  organ  is  like  wife  provided  with  peculiar  veflels,  to 
feparate  the  various  juices,  and  to  preferve  them,  without  fufl^^rv 
ing  them  to  mix  with  the  general  mafs  of  humours.  Thus  it 
is  that  we  iind  in  the  fame  vegetable,  and  frequently  in  the  fame 
organ,  juices  of  different  natures,  and  greatly  difl'ering  in  col- 
our a!:d  confidence. 

The  veflels,  wlicther  common  or  proper,  are  retained  in  the'r 
feveral  directions  by  the  ligneous  fibres ;  they  are  every  where 
furroiindcd  by  the  cellular  tiifue  j  they  open,  and  pour  their  flu- 


Nutritkn  of  Vegetables,  4^ 

id  into  glands,  into  the  cellular  tiflue,  and  into  the  utrlcules,  to 
anfwcr  the  various  functions. 

The  utricules  are  fmall  veflels  or  repofitories  which  contain 
the  pith,  and  frequently  the  colouring  matter.  They  form  a 
kind  of  repofitory  in  which  the  nutritive  juice  of  the  plant  is 
preferved,  and  whence  it  is  taken  on  occafion  ;  in  the  fame  man- 
ner as  the  colledlion  of  marrow  is  formed  in  the  internal  part 
of  the  bones,  whence  it  is  afterwards  extraded  when  the  ani- 
mal is  not  fufficiently  fupplied  with  nutriment. 

3.  The  tracheae,  or  air  veflels,  appear  to  be  the  organs  of  ref- 
plration,  or  rather  thofe  which  receive  the  air,  and  facilitate  its 
abforption  and  decompofition.  They  are  called  trachese  on  ac- 
count of  the  refemblance  which  is  thought  to  exift  between 
them  and  the  refpiratory  organs  of  infedls.  In  order  to  obferve 
them,  a  branch  of  a  tree  is  taken  fufficiently  young  to  break 
off  fliort :  after  having  cleared  away  the  bark  without  touching 
the  wood,  the  bough  is  broken  by  drawing  the  two  extremities 
in  oppofite  directions ;  the  tracheae  are  then  feen  in  the  fosm  o£ 
fmall  corkfcrews,  or  veffels  turned  in  a  fpiral  direction.  It  is 
generally  fuppofed  that  the  large  pores  which  are  perceived  in 
the  tranfverfe  fedion  of  a  plant,  viewed  in  the  microfcope,  arc 
merely  air  veffels.  It  often  happens  that  the  fap  is  extravafated 
in  the  cavity  of  the  tracheae  ;  and  they  appear  incapable  of  ferv- 
ing  any  other  purpofes  than  that  of  conveying  the  air,  at  leaft 
for  fome  time,  unlcfs  a  change  takes  place  in  the  life  of  th« 
plant. 

ARTICLE     IV. 

Concerning  the  Glands. 
Small  protuberances  are  obferved  upon  various  partfi  of  ve* 
getables.  Thefe  are  glandular  bodies  whofe  form  is  prodigiouf-- 
ly  varied.  It  is  more  particularly  upon  this  variation  of  form, 
that  Mr.  Geuttard  has  grounded  his  feven  fpecics.  They  are 
almoft  always  filled  with  a  humour,  whofc  colour  and  nature 
are  fingularly  varied. 


SECTION  II. 

Concerning  the  Nutritive  Principles  of  Vegetables. 

IF  plants  were  to  perform  no  other   aft  than   that  of 

pumping  the  nutritive  principles  they  contain  out  of  the  earth  \ 
if  they  did  not  poffefs  the  facuUy  of  digefting,  affimilating  them, 
9nd  forming  different  produ(^s,  according  to  their  nature,  and 
3-E 


4 1 S  Nuirilion  of  Vegetables, 

itlie  diverfity  of  their  organs  ;  it  would  follow,  as  a  confequence, 
that  we  ought  to  find  in  the  earth  all  thofe  principles  which 
analyfis  exhibits  to  us  in  vegetables  :  a  conclufion  which  iscon- 
tradi(Sled  by  the  fa£ls ;  for  we  fliall  hereafter  prove  that  ths 
produiflion  of  vegetable  earth  is  an  effect  of  the  organization  of 
plants,  and  that  it  owes  its  formation  to  them  inflead  of  com- 
municating principles  ready  formed  to  thofe  individuals.  If  it 
were  true  that  plants  did  nothing  but  extract  their  component 
parts  out  of  the  earth,  thofe  plants  which  grow  on  the  fame  foil 
would  poflefs  the  fame  principles,  or  at  lead  the  analogy  be- 
tween them  would  be  very  great  •,  whereas  we  find  plants  of 
very  different  virtues  and  flavours  grow  and  flourifh  befide  each 
other.  In  addition  to  this  we  may  obferve,  that  fuch  plants  as 
are  raifed  in  pure  water — the  fat  plants,  which  grow  without 
being  fixed  to  the  earth,  provided  they  are  placed  in  a  moid  at- 
mofphere — the  elafs  of  parafitical  plants,  which  do  not  partake 
of  the  properties  of  thofe  which  ferve  to  fupport  them— ^provc 
that  a  vegetable  does  not  derive  its  juices  from  the  earth,  on 
account  of  its  being  earth  *,  but  that  it  pofTefTes  an  internal  al- 
terative and  alFimilatlng  power,  which  appropriates  to  each  indi- 
vidual the  aliment  which  is  fuitable  to  it,  at  the  fame  time  that 
it  difpofes  and  combines  that  aliment  to  form  certain  peculiar 
principles.  This  digeflive  virtue  will  appear  to  be  aftonifhingly 
perfe^,  when  it  is  eonfidered  that  the  nutriment  common  to  all 
vegetables  is  very  little  varied,  fince  we  know  only  of  the  water 
and  air  ;  and  confequently  that  it  poffefTes  the  power  of  forming 
very  different  products  with  thefe  two  fimple  principles.  But 
from  this  circumftance,  that  the  nutritive  principles  of  plantg 
are  very  fimple,  it  mufl  be  prefumed  that,  in  the  various  refults 
of  digeftion,  or  (which  is  the  fame  thing)  in  the  vegetable  fol- 
ids  and  fluids,  there  muft  be  the  greateft  analogy ;  and  that  the 
differences  arc  deducible  from  the  proportion  of  the  principles, 
and  their  more  or  lefs  perfe£l  combination,  rather  than  from 
their  variety.  With  this  intention  we  (hall  carefully  obferve 
the  tranfition  from  one  principle  to  another  ;  and  fhall  explain 
the  art  of  reducing  them  all  to  certain  elementary  or  primitive 
fubftances>  fuch  as  the  fibrous  matter,  mucilage,  &c. 

ARTICLE    I.    • 

Concerning  Water,  as  a  Nutritive  Principle  of  Plants. 

Every  one  knows  that  a  plaiit  cannot  vegetate  without  the  af- 
fiftance  of  water  :  but  it  is  not  fo  generally  known  that  this  is 
the  only  aliment  which  the  root  draws  from  the  earth  ;  and  that 
a  plant  can  live,  and  propagate  itfclf,  without  any  other  aflilt- 


Nutrition  of  Ve^etahles»  j^\g 

aiKC  than  the  conta£l  of  water  and  air.  It  appears  to  me,  nev- 
crthelefs,  that  the  following  experiments  remove  every  doubt  on 
this  fubjedl :  Van  Helmont  planted  a  willow,  weighing  fifty- 
pounds,  in  a  certain  quantity  of  earth  covered  with  fheet  lead  : 
he  watered  it  for  five  years  with  diftilled  water  ;  and  at  the  end 
of  that  time  the  tree  weighed  one  hundred  fixty-nine  pounds 
three  ounces,  and  the  earth  in  which  it  had  vegetated  was  found 
to  have  fuftered  a  lofs  of  no  more  than  three  ounces.  Boyle 
repeated  the  fame  experiment  upon  a  plant,  which  at  the  end  of 
two  years  weighed  fourteen  pounds  more,  without  the  earth  in 
which  it  had  vegetated  having  loft  any  perceptible  portion  of 
its  weight. 

Meflrs.  Duhamel  and  Bonnett  fupported  plants  with  mofs, 
and  fed  them  with  mere  water  :  they  obferved  that  the  vegeta- 
tion was  of  the  moft  vigorous  kind ;  and  the  naturalilt  of  Gen- 
eva obferves,  that  the  flowers  were  more  odoriferous,  and  the 
fruit  of  a  high  flavour.  Care  was  taken  to  change  the  fupports 
before  they  could  fufFer  any  alteration.  Mr.  Tillet  has  likewife 
raifed  plants,  more  efpecially  of  the  gramineous  kind,  in  a  fimi- 
lar  manner  ;  with  this  difFerence  only,  that  his  fupports  were 
pounded  glafs,  or  quartz  in  powder.  Hales  has  obferved  that 
a  plant  which  weighed  three  pounds  gained  three  ounces  after  a 
heavy  due.  Do  we  not  every  day  obferve  hyacinths  and  other 
bulbous  plants,  as  well  as  gramineous  plants,  raifed  in  faucers  or 
bottles  containing  mere  water. 

All  plants  do  not  demand  the  fame  quantity  of  water  ;  and 
nature  has  varied  the  organs  of  the  feveral  individuals  conform- 
ably to  the  necelTity  of  their  being  fupplied  with  this  food. 
Plants  which  tranfpire  little,  fuch  as  the  mofles  and  the  lichens, 
have  no  need  of  a  confiderable  quantity  of  this  fluid  j  and  ac- 
cordingly they  are  fixed  upon  dry  rocks,  and  have  fcarcely  any 
roots  •,  but  plants  which  require  a  larger  quantity  have  roots 
whicli  extend  to  a  great  diftance,  and  abforb  humidity  through- 
out the  whole  furface. 

The  leaves  of  plants  have  likewife  the  property  of  abforbing 
water,  and  of  extracting  from  the  atmofphere  the  fame  principle 
which  the  root  draws  from  the  earth.  But  plants  which  live  in 
the  water,  and  as  it  were  fwim  in  the  element  which  ferves  thein 
for  food,  have  no  need  of  roots  ;  they  receive  the  fluid  at  all 
their  pores :  and  we  accordingly  find  that  the  fucus,  the  ulva, 
&c.  have  no  roots  whatever.  The  purer  the  water,  the  more 
falutary  it  is  to  plants.  Mr.  Duhamel  has  drawn  this  confe- 
quence  from  a  feries  of  well-made  experiments,  by  which  he 
has  proved  that  water  impregnated  with  falts  is  fatal  to  vegeta- 
|ion.     Hales  caufed  them  to  abforb  various  fluids,  by  making 


42®  Nutrition  of  Vegetables, 

incifions  In  their  roots,  and  plunging  them  in  fpirits  of  wine, 
mercury,  and  various  faline  folutions  ;  but  he  was  convinced 
that  thefe  vi^ere  all  poifons  to  the  vegetables.  Befides,  if  thefc 
falts  were  favourable  to  the  plants,  they  would  be  again  found 
in  the  individual  which  had  been  watered  with  a  folution  of 
them  ;  whereas  MelTrs.  Thouvenel  and  Cornettc  have  proved 
that  thefe  falts  do  not  pafs  into  the  vegetable.  We  muft,  nev- 
crthelefs,  except  the  marine  plants,  becaufe  the  fea  fait  of  which 
they  have  need  is  decompofed  in  them  ;  and  produces  a  princi- 
ple which  appears  neceflary  to  their  e^jilence,  fince  they  Ian- 
guifh  without  it. 

Though  it  is  proved  that  pure  water  is  more  proper  for  veget- 
ation than  water  charged  with  falts,  it  muft  not  on  that  account 
be  concluded  that  water  cannot  be  difpofed  in  a  more  favoura- 
ble manner  to  the  developement  of  vegetables,  by  charging  it 
with  the  remains  of  vegetable  and  animal  decompofition.  If, 
for  example,  the  water  be  loaded  with  principles  difengaged  by 
fermentation  or  putrefa6lion,  the  plant  then  receives  juices  al- 
ready aiTimilated  to  its  nature  \  and  thefe  prepared  aliments  muft 
haften  its  growth.  Independent  of  thofe  juices  already  formed, 
the  nitrogene  gas,  which  conftitutes  one  of  the  nutritive  princi- 
ples of  plants,  and  is  abundantly  afforded  by  the  alteration  of 
vegetables  and  animals,  muft  facilitate  their  developement.  A 
plant  fupported  by  the  remains  of  vegetables  and  animals  is  in 
the  fame  fituation  as  an  animal  fed  on  milk  only  ;  its  organs 
have  lefs  difficulty  in  elaborating  this  drink  than  that  which  has 
not  yet  been  anamalized. 

The  dung  which  is  mixed  with  earths,  and  decompofed,  not 
only  affords  the  alimentary  principles  we  have  fpoken  of;  but 
likewife  favours  the  growth  of  the  plant  by  that  conftant  and 
ileady  heat  which  ulteriour  decompofition  produces.  Thus  it  is 
that  Fabroni  affirms  his  having  obferved  the  developement  of 
leaves  and  flowers,  in  that  part  of  a  tree  only,  which  was  in  the 
vicinity  of  a  heap  of  dung. 


ARTICLE    11. 

Concerning  Earth,  and  its  Influence  in  Vegetation^ 

Although  it  be  well  proved  that  pure  water  is  fufficient  for 
the  fupport  of  plants,  we  muft  not  confider  the  earth  as  of  no 
ufe.  Its  utility  refembles  that  of  the  placenta,  which  of  itfelf 
affords  no  fupport  to  the  life  of  the  infant,  but  which  prepares 
and  difpofes  the  blood  of  the  mother  to  become  a  fuitable  nour- 
iihment  5  or  it  refembles,  and  has  a  fimilar  utility  with  theva- 


Nutrition  of  Vegetables.  ^il 

rious  refervoirs  which  nature  has  placed  in  the  body  of  man, 
to  preferve  the  feveral  humours,  and  emit  them  upon  occafion. 
The  earth  imbibes  and  retains  water ;  it  is  the  refervoir  deftin- 
ed  by  nature  to  preferve  the  elementary  juice  which  the  plant 
continually  requires  ;  and  to  furnifh  that  fluid  in  proportion  to 
its  wants,  without  expofing  it  to  the  equally  fatal  alternatives  of 
being  either  inund^ed  or  dried  up. 

We  even  fee  that,  in  the  young  plant  or  embryo,  nature  has 
not  chofen  to  entruft  the  labour  of  digeftion  to  the  ftill  feeble 
germen.  The  feed  is  formed  of  a  parenchyma,  which  imbibes 
water,  elaborates  it,  and  does  not  tranfmit  it  to  the  germen  un- 
til it  is  reduced  into  juice  or  humour.  By  infenfible  gradations 
this  feed  is  deftroyed  ;  and  the  plant  becomes  fufficiently  ftrong, 
performs  the  work  of  digeflion  without  afliftance.  In  the  fame 
manner  it  is  that  we  perceive  the  foetus  fupported  in  the  womb 
of  its  mother  by  the  humours  of  the  mother  herfelf ;  but,  when 
it  has  feen  the  light,  it  receives  for  nourifhment  a  fluid  lefs 
anamalized,  its  organs  are  gradually  flrengthened,  and  at  length 
become  capable  of  digefling  a  ilronger  and  lefs  aflimilated  nour- 
ifhment. a, 

But  on  this  very  account,  that  the  earth  is  deftined  to  tranf- 
mit to  the  plant  that  water  which  is  to  lupport  it,  the  nature  of 
the  foil  cannot  be  a  matter  of  indifference,  but  muft  be  varied 
accordingly  as  the  plant  requires  a  more  or  lefs  ccnfiderablc 
quantity  of  water,  accordingly  as  it  'demands  more  or  lefs  in  a 
given  time,  and  accordingly  as  its  roots  extend  to  a  greater  or 
lefs  diftance.  It  may  therefore  be  immediately  perceived  that  eve- 
ry kind  of  earth  is  not  fuitablc  Ibr  every  plant,  and  confequent- 
ly  that  a  flip  cannot  be  grafted  indifferently  upon  every  fpecies. 

A  proper  foil  is  that — i.  Which  affords  a  fufficiently  firm 
fupport  to  prevent  the  plant  from  being  (haken.  2.  Which  per- 
mits the  roots  to  extend  themfelves  to  a  diftance  with  eafe.  3. 
Which  becomes  impregnated  with  humidity,  and  retains  the 
water  fufficiently  that  the  plant  may  not  be  without  it  when 
wanted. — To  anfwer  thcfc  feveral  conditions,  it  is  neceffary  to 
make  a  proper  mixture  of  the  primitive  earths,  for  none  of  them 
in  particular  poflefles  them.  Silkeous  and  calcareous  earths 
may  be  confidered  as  hot  and  drying,  the  argillaceous  as  moid 
and  cold,  and  the  magnefian  as  poffeffing  intermediate  properties. 
Each  in  particular  has  its  faults,  which  render  it  unfit  for  cul- 
ture :  clay  abforbs  water,  but  does  not  communicate  it  :  calca- 
reous earth  receives  and  gives  it  too  quickly  :  but  the  properties 
of  thefe  earths  are  fo  happily  oppofed,  that  they  correct  each 
other  by  mixture.  Accordingly  we  find  that,  by  adding  lime  to 
an  argillaceous  earth,  this  lait  is  divided  ;  and  the  drying  prop- 


J^ZZ  Nutrition  cj  Vegetables, 

crty  o£  the  lime  is  mitigated,  at  the  fame  time  that  the  ftiiThcf$ 
of  the  clay  is  diminifhed.  On  thefe  accounts  it  is  that  a  finglc 
earth  cannot  conftitute  manure  j  and  that  the  character  of  the 
earth  intended  to  be  meliorated  ought  to  be  ftudied,  before  the 
choice  of  any  addition  is  decided  on.  Mr.  Tillet  has  proved  that 
the  bed  proportions  of  a  fertile  earth  for  corn,  are  three  eighths 
of  clay,  two  eighths  of  fand,  and  three  eighths  of  the  fragment* 
of  hard  ftone. 

The  advantage  of  tilling  confifts  in  dividing  the  earth,  aerat- 
ing it,  deftroying  ufelefs  or  noxious  plants,  and  converting  them 
into  manure,  by  facilitating  their  decompofition. 

Before  we  had  acquired  a  knowledge  of  the  conftituent  prin- 
ciples of  water,  it  was  impoifible  to  explain,  or  even  to  conceive, 
the  growth  of  plants  by  this  fmgle  aliment.  In  fa6l,  if  the  wa- 
ter vi^ere  an  element,  or  indecompofable  principle,  it  would  af- 
ford nothing  but  water  in  entering  into  the  nutrition  of  the 
plant,  and  the  vegetable  would  of  courfe  exhibit  that  fluid  only  : 
but  when  we  coniider  water  as  formed  by  the  combination  of 
the  oxigenous  and  hydrogenous  gafes,  it  is  eafily  underftoo4 
that  this  compound  is  reduced  to  its  principles  ;  and  that  the 
hydrogenous  gas  becomes  a  principle  of  the  vegetable,  while  the 
oxigcne  is  thrown  off  by  the  vital  forces.  Accordingly  we  fee 
the  vegetable  almoft  entirely  formed  of  hydrogene ,  Oils,  refins, 
and  mucilage,  confift  of  fcarcely  any  thing  but  this  fubftance  ; 
and  we  perceive  the  oxigenous  gas  efcape  by  the  pores,  where 
the  action  of  light  caufes  its  difengagement.  This  decompofition 
of  water  is  proved  not  only  in  vegetable,  but  like  wife  in  animal 
bodies.  Rondelet  (Lib  de  Pifc.  lib.  i.  cap.  1 2.)  cites  a  great 
number  of  examples  of  marine  animals  which  cannot  fubliit  but 
by  means  of  water,  by  the  very  conftitutions  of  their  organs. 
He  affirms  that  he  kept,  during  three  years,  a  fifh  in  a  veffel 
conftantly  maintained  full  of  very  pure  water  :  it  grew  to  fuch 
a  fize,  that  at  the  end  of  that  time  the  veffel  could  no  longer 
contain  it.  He  relates  this  as  a  very  common  fadl.  We  like- 
wife  obferve  the  red  fillies,  which  are  kept  in  glafs  veffcls,  are 
nouriihed,  and  grow,  without  any  other  affiftance  than  that  of 
the  water  properly  renewed. 

ARTICLE    III. 

Concerning  Nitrogenous  Gas,  as  a  Nutritive  Principle  of  Plants.  j| 

Vegetables  cannot  live  without  air,   but   the  air   the^  re* 
quire  is  not  the  fame  as  is  appropriated  to  m:m.     Drs.  Prieftly, 


Ingenhoufz,  and  Mr.  Senebier,  have  proved  that  it  is  the  nitro. 


i 


Nutrition  of  regetahUs*  ^35 

gcnous  gas  which  more  particularly  ferves  them  for  aliment. 
Hence  it  arifes  that  vegetation  is  more  vigorous  vt^hen  a  greater 
quantity  of  thofe  bodies  which  afford  this  gas  by  their  decompo- 
fition  are  prefented  to  the  plant  •,  thefe  are,  animals  or  vegeta- 
bles in  a  flate  of.  putrefaction.  As  the  bafis  of  nitrogenous  gas 
is  unknown  to  us,  it  is  difficult  to  conceive  what  may  be  its  ef- 
fect upon  the  vegetable  economy,  and  we  cannot  follow  it  after 
its  in  trod  I  !<f^  ion  into  the  vegetable.  We  do  not  find  it  again  un- 
til the  decompofition  of  the  vegetable  itfelf,  when  it  re-appears 
in  its  gafeous  form. 


ARTICLE    IV. 

Concerning  the  Carbonick  Acid,  as  a  Nutritive  Principle  of  Vegetables. 

The  carbonick  acid  which  is  difperfed  in  the  atmofphere,  or 
in  waters,  may  like  wife  be  confidered  as  an  aliment  of  pknts  ; 
for  thefe  bodies  pofTefs  the  power  of  abforbing  and  decompofing 
it  when  its  quantity  is  fmall.  The  bafe  of  this  acid  even  feems 
to  contribute  to  the  formation  of  vegetable  fibres  :  for  I  have  ob- 
ferved  that  this  acid  predominates  in  the  fungus,  and  other  fub- 
terraneous  plants.  But  by  caufing  thefe  vegetables,  together 
with  the  body  upon  which  they  were  fixed,  topafsby  impercep- 
tible gradations  from  an  almoft  abfolute  darknefs  into  the  light> 
the  acid  very  nearly  difappeared  ;  the  vegetable  fibres  being  pro- 
portionally increafed,  at  the  fame  time  that  the  refin  and  colour- 
ing principles  were  developed  by  the  oxigene  of  the  fame  acid. 
Senebier  has  obferved,  that  the  plants  which  he  watered  with 
water  impregnated  with  the  carbonick  acid,  tranfpired  a  much 
greater  quantity  of  oxigenous  gas ;  which  proves  a  decompofi- 
tion of  the  carbonick  acid. 

Vegetation  may  therefore  be  fuccefsfully  employed  to  correal 
air  too  highly  charged  with  cd:rbonick  acid,  or  in  which  the  ni- 
Irogenous  gas  exifts  in  too  great  a  proportion. 


ARTICLE    V. 

Concerning  Light,  and  its  influence  on  Vegetation. 

Light  is  abfolutely  necefTary  to  plants.  Without  the  affif!- 
ance  of  this  principle  they  become  pale,  languifh,  and  die.  But 
it  has  not  been  proved  that  it  enters  as  an  aliment  into  their 
cornpofition  :  at  mofl  it  may  be  confidered  as  a  flimulus  or  agent 
which  decompofes  the  various  nutritive  principles,  and  feparate* 


4^4  Nutrition  of  Vegetables* 

the  oxigcnotts  gas  arifing  from  the  decompofition  of  water,  or 
the  carbonick  acid,  while  their  bafes  become  fixed  in  the  plant 
itfelf. 

The  moft  immediate  effect  of  the  fixation  of  the  various  fub- 
flances,  and  the  concretion  of  the  liquids,  which  ferve  as  the  food 
of  plants,  is  a  fenfible  production  of  heat,  which  caufes  plants 
to  participate  very  little  in  the  temperature  of  the  atmofphere. 
Dr.  Hunter  obferved,  by  keeping  a  thermometer  plunged  in  a 
hole  made  in  a  found  tree,  that  it  conftantly  indicated  a  temper- 
ature feveral  degrees  above  that  of  the  atmofphere,  when  it  was 
below  the  fifty-fixth  divifion  of  Fahrenheit  ;  whereas  the  vege- 
table heat  in  hotter  weather,  was  always  feveral  degrees  below 
that  of  the  atmofphere.  The  fame  philofopher  has  likewife  ob- 
ferved, that  the  fap  which  out  of  the  tree,  would  freeze  at  32**, 
did  not  freeze  in  the  tree  unlefs  the  cold  were  augmented  i^* 
more. 

The  vegetable  heat  may  increafe  or  diminifh,  by  feveral  cau- 
fes, of  the  nature  of  difeafe  \  and  it  may  even  become  percept- 
ible to  the  touch  in  very  cold  weather,  according  to  Mr.Buffon. 

The  heat  produced  in  healthy  vegetables,  by  the  before  men- 
tioned caufes  continually  tempers  the  cold  of  the  atmofphere  : 
the  evaporation  which  takes  place  through  the  whole  body  of 
the  tree,  continually  moderates  the  fcorching  heat  of  the  fun  ; 
and  thefe  productive  caufes  of  cold  or  heat  are  more  effe£lual, 
in  proportion  as  the  heat  or  cold  of  external  bodies  a£ls  with 
greater  energy. 

The  property  which  plants  poffefs  of  converting  nitrogenous 
gas  and  carbonick  acid  into  nouriiliment,  eftablifhes  an  aftonifh- 
ing  degree  of  analogy  between  them  and  certain  infeCls.  It  ap- 
pears, from  the  observation  of  Frederick  German  (Ephem.  des 
Curiof.  Nat.  Anne'e  1670,)  that  the  air  may  become  a  real  food 
for  the  clafs  of  fpiders.  The  larvae  of  the  ant,  as  well  as  of  fev- 
eral infeCls  of  prey  which  live  in  the  fand,  increafe  in  bulk, 
and  undergo  their  metamorphofes  without  any  other  nourifii- 
ment  than  that  of  the  air.  It  has  been  obferved  that  a  great 
number  of  infeCts,  particularly  in  the  ftate  of  larvx,  are  capa- 
ble of  living  in  the  nitrogenous  gas,  mixed  with  carbonick  acid, 
and  tranfpiring  vital  air.  The  abbe  Fontana  has  obferved  that 
feveral  infects  poflefs  this  property  ;  and  Ingenhoufzy  who  is  of 
opinion  that  the  green  matter  which  is  formed  in  water,  and 
tranfpires  oxigenous  gas  by  the  light  of  the  fun,  is  a  clufter  of 
animalcula,  has  added  to  thefe  ph^enomena.  Infe6\;s  have  more- 
over the  organ  of  refpiration  diftributed  over  the  whole  furface 
of  their  bodies.  Here  therefore  we  obferve  feveral  very  afton- 
ifhing  points  of  analogy  between  infcds  and   vegetables  ;    and 


Concerning  Mucilage,  425 

the  chemical  analyfis  adds  flill  more  to  thefe  refcmblances,  Gnce 
infects  and  vegetables  afford  the  fanae  principles  ;  namely,  vola- 
tile oils,  rcfins,  difengaged  acids,  &c. 


SECTION    III. 

Concerning  the  Refults  of  Nutrition,  or  the  Vegetable  Principles. 

X  HE  various  fubdances  which  afford  food  to  plants, 
are  changed  by  the  organization  of  the  vegetable  ;  from  which 
there  refulcs  a  fluid  generally  diftributed,  and  known  by  the 
name  of  Sap.  This  juice,  when  conveyed  into  the  feveral  parts 
of  the  plant,  receives  an  infinity  of  modifications,  and  forms  the 
feveral  humours  which  are  feparated  and  afforded  by  the  organs. 
It  is  to  thefe  principles  chiefly  that  we  are  at  prefent  about  to 
direcl  our  attention  •,  and  we  fhall  endeavour  in  our  examina- 
tion to  follow  the  moft  natural  order,  by  fubjeiSling  them  to 
analyfis  in  the  fame  order  as  that  in  which  nature  prefents  them 
to  us. 


ARTICLE    I. 

Concerning  Mucilage. 

Mucilage  appears  to  conftitute  the  firll  alteration  of  the  ali- 
mentary juices  in  vegetables.  Moft  feeds  are  almoft  totally  re- 
folvable  into  mucilage,  and  young  plants  feem  to  be  entirely 
formed  of  it.  This  fubftance  has  the  greateft  analogy  with  the 
mucous  fluid  of  animals.  Like  that  fluid,  it  is  mofl  abundant 
in  the  earlier  periods  of  life,  and  all  the  other  principles  appear 
to  be  derived  from  it ;  and  in  vegetables,  as  well  as  animals,  its 
quantity  becomes  lefs  in  proportion  as  the  increafe  of  magnitude, 
or  growth  of  the  individual,  becomes  lets,  or  ceafes.  Mucilage 
is  not  only  the  nutritive  juice  of  plants  and  animals  ;  but,  whea 
extra^fted  from  either,  it  becomes  the  moft  nouriftiing  and 
wholefome  food  we  are  acquainted  with.  , 

Mucilage  forms  the  bafis  of  the  proper  juices,  or  the  fap  of 
plants.  It  is  fometimes  found  almoft  entirely  alone,  as  in  mal- 
lows, the  feeds  of  the  wild  quince,  linfeed,  the  feeds  of  thlafpi, 
&c.  Sometimes  it  is  combined  with  fubftaaces  infoluble  ia 
3...F 


426  Gum  or  Mucilage, 

water,  which  it  keeps  fufpended  In  the  form  of  an  cmulfion  j 
as  in  the  euphorbium,  celandine,  the  convolvulus,  and  others.  In 
other  inftances  it  is  united  with  an  oil  and  forms  the  fat  oils. 
Frequently  it  is  united  with  fugar  ;  as  in  the  gramineous  feeds, 
the  fugar-cane,  maize,  carrot,  &g.  It  is  likewife  found  con- 
founded with  the  ell'ential  falts,  with  excefs  of  acid,  as  in  bar- 
berries, tamarinds,  forrel,  &c. 

Mucilage  fometimes  conftitutes  the  permanent  ftate  of  the 
plant ;  as  in  the  tremella,  the  conferva,  fome  lichens,  and  moft 
of  the  champignons.  This  exiftence  in  the  form  of  mucilage  is 
likewife  feen  in  certain  animals  ;  fuch  as  tlie  medufa  or  fea- 
nettle,  the  holothurion,  &c. 

The  chara£^ers  of  mucilage  are — i.  Infipldity.  2.  Solubil- 
ity in  water.  3.  Infolubillty  in  alcohol.  4.  Coagulation  by  the 
allien  of  weak  acids.  5.  The  eroifiionof  a  confiderable  quan- 
tity of  carbonick  acid,  when  expofed  to  the  a6lion  of  fire ;  at 
the  fame  time  that  it  becomes  converted  into  coal,  without  ex- 
hibiting any  fiame.  Mucilage  is  likewife  capable  of  pafling  to 
the  acid  fermentation  when  diluted  with  water. 

The  formation  of  mucilage  appears  to  be  almoft  independent 
of  light.  Thofe  plants  which  grow  in  fubterraneous  places  a- 
bound  with  it.  But  light  is  required  to  enable  mucilage  to  pafs 
to  other  ftates,  for,  without  the  afliftancc  of  this  principle,  the 
fame  plants  would  obtain  fcarcely  any  confidence. 

That  which  is  called  gum,  or  gummy  juices,  in  commerce, 
is  nothing  but  dried  mucilage.  Thefe  gums  are  three  in  num- 
ber. They  either  flow  naturally  from  the  trunk  of  the  tree 
which  affords  them,  or  they  are  obtained  by  incifion  of  the 
bark. 

1.  Gums  of  the  country,  Gummi  nojlras. — This  gum  flows 
naturally  from  certain  trees  in  our  climate,  fuch  as  the  plumb, 
the  peach,  the  cherry-tree,  &c.  It  fird  appears  in  the  form  of 
a  thick  fluid,  which  congeals  by  expofure  to  the  air,  and  lofes 
theadhefive  and  gluey  confiftence  which  characterizes  it  in  the 
liquid  ftate.  Its  colour  is  white,  but  more  commonly  yellow 
or  reddlfh.  When  pure,  it  may  be  advantageoufly  fubftituted 
for  gum  arabick,  which  is  much  dearer. 

2.  Gum  arabick,— The  gum  arabick  flo\^s  naturally  from  the  a- 
cacia  in  Egypt  and  Arabia.  It  is  even  affirmed  that  iris  not  obtain- 
ed from  this  tree  only,  but  that  the  gum  met  with  in  commerce 
is  the  produce  of  feveral  trees.  The  appearance  of  rhis  gum  is  in 
round  pieces,  white  and  tranfparent,  wrinkled  without  and  hollow 
within  ;  it  is  likewife  found  in  round  pieces  varioufly  contorted. 
This  gum  is  eafily  foluMe  in  va^  ater,  and  forms  a  tranfparent 
jelly  called  muciliige.     It  is  mu :  h  ufed  in  the  arts  and  in  medi- 


Gums.     Oih^  427 

aluc.  It  ts  mild,  void  of  fmell  or  tafle,  very  well  adapted  to 
ferve  as  the  bafis  of  paftils  and  other  preparations  ufed  as  miti- 
gating or  foftening  remedies. 

3.  Gum  adragant. — The  gum  adragant  is  nearly  of  the  fame 
nature  as  gum  arabick.  It  flows  from  the  adragant  of  Crete;  a 
fmall  ilirub  not  exceeding  three  feet  in  height.  It  comes  to  ua 
in  fmall  white  tears,  contorted,  and  refembling  little  worms. 
It  forms  with  water  a  thicker  jelly  than  gum  arabick,  and  may 
be  ufed  for  the  fame  purpofes. 

If  the  roots  of  marihmallows,  or  of  the  confolida,  llnfeed,  the 
kernels  of  the  wild  quince  (coing),  &c.  be  macerated  in  water 
for  a  time  they  atTord  a  mucilage  fimilar  to  that  of  gum  arabick. 

All  thefe  gums  afford  by  diftillation,  water,  an  acid,  a  fmall 
quantity  of  oiJ,  a  fmall  quantity  of  ammoniack  or  volatile  alkali, 
and  much  coal.  This  fketch  of  analyfis  proves  that  mucilage  is 
compofed  only  of  water,  oil,  acid,  carbone,  and  earth  \  and 
fhows  that  the  various  principles  of  the  alimentary  juices,  fuch 
as  water,  the  carbonick  acid,  and  nitrogene  gas,  are  fcarcely 
changed  in  this  lubflance. 

Gums  are  ufed  in  the  arts  and  in  medicine.  In  the  arts  they 
are  applied  to  give  a  greater  degree  of  confiftence  to  certain  col- 
ours, and  to  fix  them  more  permanently  upon  paper  ;  they  arc 
alfo  ufed  as  a  preparation  to  give  a  firmer  body  to  hats,  ribbonds, 
taffetas,  &c.  Stuffs  dipped  in  gum  water  acquire  a  luftre  and 
brightnefs ;  but  water,  and  the  handling  of  thefe  goods,  foon 
dcitroy  the  illufion  ;  and  thefe  proceffes  are  clalTed  among  thofe 
which  nearly  approach  to  impofition  and  deceit.  Gum  is  like- 
wife  the  baiis  of  moft  kinds  of  blacking  uied  for  ihoes,  boots, 
and  the  like. 

The  gums  are  ordered  in  medicine  as  emollients.  They  com- 
pofe  the  bafis  of  many  remedies  of  this  kind.  The  mucilage  of 
linfeed,  or  of  the  kernels  of  wild  quinces,  is  of  value  in  allaying 
inflammations. 


ARTICLE    II. 
Concerning  Oils. 

By  common  confent  the  name  of  Oil  is  given  to  fat  un£li>« 
©us  fubltances,  more  or  lefs  fluid,  infoluble  in  water,  and  com- 
buflible. 

Thefe  products  appear  to  belong  exc  lufively  to  animals  aad 
vegetables.     The  mineral  kingdom  exhib  its  only  a  few  fubfta-n- 


42S  Fixed  and  Volatile  Oils* 

CCS  of  this  Aature,  which  poflefs  fcarcely  any  of  the  above  prop- 
erties, fuch  as  the  uniSluous  property. 

Oils  are  diflinguiflied,  relative  to  their  fixity,  into  fat  oils, 
and  eflential  oils.  We  (hall  defcribe  them  in  this  article  under 
the  names  of  Fixed  Oils  and  Volatile  Oils.  The  difl'erence  be- 
tv/ecn  thefe  two  kinds  of  oils  do  not  merely  confifl  in  their  various 
ficgrees  of  volatility,  but  alfo  in  their  habitudes  v/ith  the  feveral 
ic-agcnts. ,  The  fixed  oils  are  infoluble  in  alcohol,  but  the  vola- 
tile oils  arc  eafily  diflblved  :  the  fixed  oils  are  in  general  mild  j 
wliiie  the  volatile  are  acrid  and  even  cauftick. 

it  appears  neverthelefs  that  the  oily  principle  is  the  fame  in 
both  ;  but  it  is  combined  with  mucilage  in  the  fixed  oils,  and 
with  die  fpiritus  re£lor,  or  aroma,  in  the  volatile  oils.  By  burn- 
ing the  mucilage  of  fixed  oils  by  diftiilation,  they  become  more 
v.Vxd  more  attenuated  ;  the  fame  may  likev/ife  be  done  by  means 
of  water,  which  diflblves  this  principle.  By  diftilling  volatile 
oil  wiiii  a  fmall  quantity  of  water,  by  the  gentle  heat  of  a  water 
bath,  the  aroma  is  feparated,  and  this  may  be  again  reltored  by 
re-diRiliing  it  with  the  odorant  plant  which  originally  afforded  it. 

Volatile  oil  is  ufually  found  in  the  moft  odorant  part  of  any 
plant.  In  unbelliferous  plants  it  is  found  in  the  feed  ;  in  the 
geurn,  the  root  affords  it  ,  and  in  the  labiated  plants  it  is  found 
in  the  branches  and  leaves.  The  fimilitude  between  volatile 
oils  nr/H  ether,  which  appears  to  be  merely  a  combination  of  ox~ 
igcne  Lind  alcohol,  proves  that  the  volatile  oils  may  be  nothing 
but  a  combination  of  the  fermentefcible  bafis  of  fugar  with  oxi- 
gene.  Hence  we  may  form  a  notion  how  oil  is  formed  in  the 
diliil'aiion  of  mucilage  and  of  fugar  ;  and  we  fhall  no  longer  be 
furprikd  to  find  that  the  volatile  oils  are  acrid  and  corrofive, 
tiiat  tiicy  redden  blue  paper,  attack  and  deftroy  cork,  and  ap- 
|)rGach  10  the  properties  of  acids.  We  fhall  now  proceed  to 
treat  of  fixed  and  volatile  oils  feparately.  , 


DIVISION    I. 

Cancerning  Fized  Oils- 

Mofl  of  the  fixed  oils  arc  fluid  ;  but  the  greater  number  are 
capable  of  paffmg  to  the  Hate  of  folidity,  even  by  a  moderate 
degree  cf  cold.  There  are  fome  which  conltantly  poffefs  that 
form  in  the  temperature  of  our  climates  ;  fuch  as  the  butter  of 
cacao,  wax,  and  the  pela  of  the  Chinefe.  They  all  congeal  at 
different  ticgrees  of  cold.  Olive  oils  become  folid  at  lo**  below 
zero  of  Reaumur  ;  oil  of  almonds  at  the  fame  degree  ;  but  nut 
fil  do'is  ivjt  freeze  in  our  climates. 


Oil  of  Almonds,  J^2p 

The  fixed  oils  poiTefs  a  very  evident  degree  of  utK^uofity,  do 

not  mix  either  with  water  or  alcohol,  are  volatilized  at  a  degree 
of  heat  fuperiour  to  that  of  boiling  water,  and  when  volatiUzed 
they  take  fire  by  the  contadl:  of  an  ignited  body. 

The  fixed  oils  are  contained  in  the  kernels  of  (hell  fruits  or 
nuts  5  in  the  pippins,  and  fometimes  in  all  the  parts  of  fruits, 
fuch  as  olives  and  almonds,  all  whofe  parts  are  capable  of  afford- 
ing them. 

The  oil  is  ufually  made  to  flow  by  expreffion  out  of  the  cellules 
which  contain  it :  but  each  fpecies  requires  a  diira  t-nt  manage- 
ment. 

I.  Olive  oil  is  obtained  by  expreffion  from  the  fruit  of  the 
olive  tree.  The  procefs  ufed  by  us  is  very  fimple.  The  olive 
is  crufhed  by  a  mill  ftone,  placed  vertically,  rolling  upon  an 
horizontal  plane.  The  pafte  thus  formed  is  ftrongly  prefTed  in 
a  prefs  ;  and  the  firfl  oil  which  comes  out  is  called  Virgin  Oil. 
The  marc  or-  pulp  is  then  moiftened  with  boiling  water  ;  the 
mafs  is  again  prelFed  ;  and  the  oil  which  floats  upon  the  water 
carries  with  it  part  of  the  parenchyma  of  the  fruit,  and  a  great 
part  of  the  mucilage,  from  which  it  is  difficultly  cleared. 

The  difference  in  the  kind  of  olive  produces  a  difference  in  the 
oil  j  but  the  concurrent  circumftances  Hkewife  eftablifli  other 
differences.  If  the  olive  be  not  fufficiently  ripe,  the  oil  is  bitter  ; 
if  it  be  too  ripe,  the  oil  is  thick  and  glutinous.  The  method  of 
extratfting  the  oil  has  a  very  great  influence  on  its  quality.  The 
oil  mills  are  not  kept  fufficiently  clean  •,  the  mill  ilones,  and  all 
the  utenfils,  are  impregnated  with  a  rancid  oil,  which  cannot 
but  communicate  its  flavour  to  the  new  oil.  In  fome  coumries 
it  is  ufual  to  lay  the  olives  in  heaps,  and  fuffer  them  to  ferment 
before  the  oil  is  drawn.  By  this  management  the  oil  is  bad  ; 
and  this  procefs  can  only  be  ufed  for  oil  intended  for  the  lamp 
or  for  the  foap  boiler. 

t.  Oil  of  almonds  is  extraiSled  from  that  fruit  by  expreffion. 
For  this  purpofe  dry  almonds  are  put  into  a  coarfe  fack,  and  ag- 
itated rather  ilrongly,  to  difengage  an  acrid  powder  which  ad- 
heres to  the  fkin.  They  arc  then  pounded  in  a  marble  mortar 
into  a  pailc,  which  is  wrapped  in  a  coarfe  cloth,  and  fubje£led 
to  the  prefs. 

This  oil  is  greenifti  and  turpid  when  frcffi,  becaufe  the  a£llon 
of  the  prefs  caufes  part  of  the  mucilage  to  pafs  through  the 
cloth  ;  as  it  becomes  older  it  is  clearer,  but  is  acrid  by  the  decom- 
pofition  of  the  fame  mucilage. 

8omc  perfons  throw  almonds  into  hot  water,  or  expofe  them 
to  fleam,  be  lore  they  prefs  them  ;  but  this  addition  of  water 
difpofes  the  oils  to  become  rancid  more  fpecdily. 


43*  0'^  £/*  -Almonis. 

By  this  procefs  the  oil  of  all  kinds  of  almonds,  nuts,  and  fccds> 
may  be  extradled. 

3.  Linieed  oil  is  extra£ted  from  the  feed  of  the  plant  linum. 
As  this  feed  contains  much  mucilage,  it  is  torrefied  before  it  is 
fubjedted  to  the  prefs.  This  previous  treatment  gives  the  oil 
a  dilagreeable  empyreumatick  flavour  :  but  at  the  fame  time  de- 
prives it  of  the  property  of  becoming  rancid,  and  renders  it  one 
of  the  molt  drying  oils.  All  mucilaginous  feeds,  all  kernels j 
and  the  feeds  of  henbane  and  of  the  poppy,  ought  to  be  treated 
in  the  lame  manner. 

If  a  fat  oil  be  diflilled  in  a  proper  apparatus  of  veflels,  the 
produdl:  is,  phlegm  j  an  acid  -,  a  fluid  or  light  oil,  which  becomes 
thicker  towards  the  end  ;  much  hydrogenous  gas,  mixed  with 
carbonick  acid  ;  and  a  coaly  refidue,  which  affords  no  alkaH.  I 
have  obferved  that  the  volatile  oils  afford  more  hydrogenous  gas, 
and  the  fixed  more  carbonick  acid  :  this  laft  produtf  depends 
on  the  mucilage.  By  difliliing  the  fame  oil  repeatedly,  it  is 
more  and  more  attenuated,  becomes  very  limpid  and  very  vola- 
tile, with  the  only  difference  it  has  required  the  peculiar  odour 
communicated  by  the  fire.  The  volatilization  of  the  oil  may 
be  accelerated  by  difliliing  it  from  an  argillaceous  earth  ;  by  this 
means  it  is  in  a  fhort  time  deprived  of  its  colouring  part :  and 
•the  heavy  oils  which  afford  bitumens,  when  diflilled  once  or 
twice  from  clay  alone,  fuch  as  that  of  Murviei,  are  rendered  per- 
4edly  colourlefs.  The  ancient  chemiits  prepared  oleum  philofa- 
phorum  by  difliliing  oil  from  a  brick  previoufiy  impregnated  with 
it. 

I.  Oil  eafily  combines  "with  oxigene.  This  combination  is 
cither  flow  ur  rapid.  In  the  firfl  cafe,  rancidity  is  the  confe- 
quence  ;  in  the  fecond  inflammation. 

Fixed  oil  expofed  for  a  certain  time  to  the  open  air,  abforbs 
the  oxigenous  gas,  and  acquires  a  peculiar  odour  of  fire,  an 
acrid  and  burnt  tafle,  at  the  fame  time  that  it  becomes  thick  and 
coloured.  If  oil  be  put  in  conta£l  with  oxigene  in  a  bottle,  it 
becomes  more  fpeedily  rancid,  and  ihe  oxigene  is  abforbed. 
Scheeie  obferved  the  abforption  of  a  portion  of  the  air  before 
the  theory  was  well  afcertained.  Oil  is  not  fubjedl  to  alteration 
in  clofed  veffels. 

It  feems  that  oxigene,  combined  with  the  mucilage,  confl:!- 
tutes  rancidity  -,  and  that,  when  combined  with  the  oil  itfelf,  it 
forms  drying  oil. 

The  rancidity  of  oils  is  therefore  an  efi^ecl  analogous  to  the 
calcination  or  oxidation  of  metals.  It  elfentially  depends  on 
the  combination  of  pure  air  with  the  extradlive  principle,  which 
is  naturally  united  with  the  oily  principle.     We  may  carry  this 


Purification  tif  Oils* 


45 » 


mference  to  demonftration,    by  attending  to  the  procefles  ufed 
to  counteract  or  prevent  the  rancidity  of   oils. 

A.  When  olives  are  prepared  for  the  table,  every  endeavour 
is  ufed  to  deprive  them  of  this  principle,  which  determines  their 
fermentation  •,  and  for  this  purpofe  various  methods  are  ufed.  Ii* 
fome  places  they  are  macerated  in  boiling  water,  charged  with 
fait  and  aromaticks ;  and,  after  twenty-four  hours  digellion, 
they  are  fteeped  in  clear  water,  which  is  renewed  till  their  taflc 
is  perfe6lly  mild.  Sometimes  nothing  more  is  done  than  to 
macerate  the  olives  in  cold  water  ;  but  they  are  frequently  ma- 
cerated in  a  lixivium  of  quick-lime  and  wood  aihes,  after  which 
they  are  wafhed  in  clear  water.  But  in  whatever  manner  the 
preparation  is  made,  they  are  preferved  in  a  pickle  charged  with 
fome  aromatick  plant,  fuch  as  coriander  and  fennel.  Some  per- 
fons  preferve  them  whole  ;  others  fplit  them,  for  the  more 
complete  extraction  of  their  mucilage,  and  in  order  that  they 
may  be  more  perfectly  impregnated  with  the  aromaticks. 

All  thefe  procefles  evidently  tend  to  extract  the  mucilaginous 
principle,  which  is  foluble  in  water,  and  by  this  means  to  pre- 
ferve the  fruit  from  fermentation.  When  the  operation  is  not 
well  made,  the  olives  ferment  and  change.  If  olives  be  treated 
with  boiling  water,  to  extra£t  the  mucilage,  before  they  are 
fubmitted  to  the  prefs,  a  fine  oil  will  be  obtained,  without  dan- 
ger of  rancidity. 

B.  When  the  oil  is  made,  if  it  be  ftrongly  agitated  in  wa- 
ter, the  mucilaginous  principle  is  difengaged  ♦,  and  the  oil  may 
be  afterwards  preferved  for  a  long  time  without  change.  I 
have  preferved  oil  of  the  marc  of  olives,  prepared  in  this  man- 
ner, for  feveral  years,  in  open  bottles,  without  any  alteration. 

C  The  torrefaClion  to  which  feveral  mucilaginous  feeds  are 
fubje£ted  before  the  extraction  of  the  oil,  renders  them  lefs  fuf- 
ceptible  of  change,    becaufe  the  mucilage  has  been  dedroyed. 

D.  M.  Sieffert  has  propofed  to  ferment  oils  with  apples  or 
pears,  in  order  to  deprive  rancid  oils  of  their  acrimony.  By 
this  means  they  are  cleared  of  the  principle  which  had  combin- 
ed with  them,  but  now  becomes  attached  to  other  bodies. 

Mucilage  may  therefore  be  confidered  as  the  feed  of  fermen- 
tation. 

When  the  combination  of  the  pure  air  is  favoured  by  the  vol- 
atilization of  the  oil,  iiiflammation  and  combuftion  are  then  the 
confequence.  To  carry  this  combination  into  efledt,  the  oil 
muft  be  volatilized  by  the  application  of  a  heated  body  ;  and  ths 
flame  which  is  produced  is  then  fulficient  to  maintain  the  de- 
gree of  volatility,  and  fupport  the  combuftion.  When  a  current 
•f  air  is   caufed  iq  pal*  through  the  middle  of  the  wick  and  the 


43^  &mhinaitons  of  Oils, 

flame,  the  great  quantity  of  oxigene  which  mud  then  neceffari- 
ly  pafs,  occafions  a  more  rapid  combuftion.  Hence  it  is  that  the 
light  is  ftronger,  and  without  fmoke ;  for  this  is  deftroyed  and 
confumed  by  the  violent  heat  which  is  excited. 

The  lamps  of  Palmer  are  likewife  entitled  to  our  particular 
attention.  By  caufing  the  rays  to  pafs  through  a  liquor  colour- 
ed blue,  he  p^erfedtly  imitates  the  light  of  the  day ;  which 
proves  that  the  artificial  rays  require  to  be  mixed  with  the  blue, 
to  imitate  the  natural  ;  and  the  folar  rays  which  pafs  through 
the  atmofphere,  may  owe  their  colour  to  their  combination  with 
the  blue  colour  \^hich  appears  to  predominate  in  the  air. 

If  water  be  projected  upon  oil  in  a  ftate  of  inflammation,    it 
is  known  that  extinction  does  not  happen,  becaufe  the  water  is 
decompofed  in  this  experiment.      If  the  produdl  of  the   com- 
buftion of  oil  be  colle'ited,  much  water  is  obtained,  becaufe  the 
combination  of  its  hydrogene  with  oxigene  produces  that  fluid. 
Mr.  Lavoifier  has  proved  that  one  pound  of  olive  oil  contains. 
Coal  or  carbone,  1 2  ounces,  5  gros,  5  grains  ; 
Hydrogene,  3  2         67. 

The  art  of  rendering  oils  drying,  likewife  depends  on  the 
Combination  of  oxigene  with  the  oil  itfelf.  For  this  purpofe, 
nothing  more  is  required  than  to  boil  it  with  oxides.  If  an  oil 
be  heated  upon  the  red  oxide  of  mercury,  a  confiderable  ebulli- 
tion enfues,  the  mercury  is  reduced,  and  the  oil  becomes  very 
drying  :  this  is  an  obfervation  of  Mr.  Puymaurin.  The  oxides 
of  lead  or  copper  are  commonly  ufed  for  this  purpofe.  An  ex- 
change of  principles  takes  place  in  this  operation  ;  the  mucilage 
combines  with  the  metal,  while  the  oxigene  unites  with  the  oil. 
Oil  may  likewife  be  combined  with  the  metallick  oxides  by 
double  affinity,  after  the  manner  of  Berthollet.  For  this  pur- 
pofe a  iblution  of  foap  is  poured  into  a  metallick  folution.  By 
this  means  a  foap  of  a  green  colour  is  prepared  with  a  fulphate 
of  copper ;  and,  with  that  of -iron,  a  foap  of  a  deep  brown  col- 
our, of  confiderable  intenfity. 

•It  appears  that,  in  the  combinations  of  fixed  oils  with  the  ox- 
ides of  lead,  a  fubftance  is  difengaged,  and  fwims  at  the  top, 
which  Scheele  called  the  Sweet  Principle,  and  feems  to  be  fim- 
ply  mucilage. 

2.  Oil  combines  with  fu^nr,  and  aflfords  a  kind  of  foap, 
which  may  be  eafily  diffufed  in  water,  and  kept  fufpended. 
The  trituration  of  almonds  with  fugar  and  water,  forms  the 
lac  amygdale,  orgeat,  and  other  emulfions.  Combinations  of 
this  kind  exift  ready  formed  in  the  vegetable  kingdom.' 

3.  Oil  unites  readily  with  alkalis;  and  the  refult  of  this  un- 
ion is  the  well-known  compound,  foap..     To  this  effedpot-alh. 


ManufaElure  of  ^oapu  435 

•r  pure  alkali  may  be  triturated  with  oil,  and  the  mixture  con- 
centrated by  fire.  The  medicinal  foap  is  made  with  oil  of  fweet 
almonds,  and  half  its  weight  of  pot-afh  or  cauftick  alkali.  The 
foap  becomes  hard  by  ftandin^. 

To  make  the  foap  of  commerce,  one  part  of  good  foda  of  Al- 
icant  mufl  be  boiled  with  two  of  quicklime,  in  a  fufficient 
quantity  of  water.  The  liquor  is  then  to  be  drained  through 
a  cloth  \  and  evaporated  to  that  degree,  that  a  phial  which  con- 
tains eight  of  pure  water,  may  hold  eleven  of  the  faline  folution, 
which  is  ufually  called  Soap  Lye  or  Lees.  One  part  of  this 
lixivium,  and  two  of  oil,  boiled  together,  till  upon  trial  with  a 
fpatula  it  eafily  feparates,    and  foon  coagulates,  form  foap. 

In  moft  manufaftories  the  lixivium  is  prepared  without  heat. 
Equal  volumes  of  pounded  foda  of  Alicant,  and  quicklime  pre- 
vioufly  flacked,  are  mixed  together.  Water  is  thrown  on  this 
mixture,  which  filters  through,  and  is  conveyed  into  a  proper 
vefiel.  Water  is  poured  on  till  it  pafles  through  without  ac- 
quiring any  more  .fait.  In  this  way  thefe  kinds  of  lyes  are  ob- 
tained, which  difl^er  in  ftrength  ;  that  which  pafles  firft  is  the 
ftrongeft,  and  the  laft  Is  almofl:  mere  water.  Thefe  are  after- 
wards mixed  with  oil  in  boilers,  where  the  mixture  is  favoured 
by  heat.  The  weak  lye  is  firfi:  added,  and  afterwards  gradually 
the  flron^er  ;  and  the  ftrongefl  is  not  added  till  towards  the  end 
of  the  procefs. 

To  make  the  foap  marbled,  they  make  ufe  of  foda  in  the  mafs, 
fclue  copperas,  cinnabar,  ^c.  according  to  the  colour  defired. 

A  liquid  green  or  black  foap  is  likewife  made  by  boiling  the 
lixivium  of  foda,  pot-afh,  or  even  wood  aflies,  with  the  marc 
of  the  oils  of  olive,  of  nuts,  or  of  nape  5  or  with  fat,  or  fifli  oil, 
&c.  The  black  foap  is  made  in  Picardy,  and  the  green  in  Hol- 
land. The  Marquis  de  Bouillon  has  propofed  to  make  foaps 
with  animal  fat. 

At  Aniane,  in  the  neighbourhood  of  Montpellier,  a  foft  foap 
i*  prepared  with  cauftick  lixivium  of  wood  afhes,  and  the  oil  or 
the  marc  of  olives. 

If  foap  be  cxpofed  to  dIfl:ilIation,  the  refult  is  water,  oil,  and 
much  ammoniack ;  and  there  remains  in  the  retort  a  large  quan- 
tity of  the  alkali  ufed  in  the  fabrication  of  the  foap.  The  am- 
moniack which  is  produced  in  this  experiment  appears  to  mc 
toarife  frorii  the  combination  of  the  hydrogenous  gas  of  the  oil 
with  the  nitrogene,  a  conftituent  principle  of  the  fixed  alkali. 

Soap  is  foluble  in  pure  water ;  but  it  forms  curds,  and  is  de- 
compofed  in  water  abounding  with  fulphatcs  :  becaufe  the  ful- 
phurick  acid  feizes  the  alkali  of  the  foap ;  while  the  earth  corn- 
Vines  with  the  oil,  and  forms  a  foap  which  fwiras  at  the  furface* 
3-..G 


434  EffeBs  of  Acids  on  Oils, 

Soap  IS  llkewife  foluble  in  alcohol  by  the  affiftance  ofa  gentle 
heat ;  and  forms  tlie  eficnce  of  ibap,  or  opodeldock,  which  may 
be  fcented  at  pleafure. 

Soaps  are  capable  of  combining  with  a  larger  quantity  of  oil, 
and  rendering  it  foluble  in  water.  Hence  their  property  of 
cleanfmg  cloths,  linens,  &c.  They  are  ufed  as  deobitruents  in 
medicine. 

4.  The  fixed  oils  unite  likewife  with  acids.  Meffrs.  Achard, 
Cornette,  and  Macquer,  have  attended  to  thefe  combinations. 
Achard  gradually  adds  the  concentrated  fulphurick  acid  to  tlie 
fixed  oil ;  the  mixture  being  triturated,  a  mafs  is  obtained  which 
is  foluble  in  water  and  in  alcohol. 

The  fuming  nitrick  acid  immediately  turns  the  fixed  oils  blacky 
and  fets  fire  to  fuch  as  are  drying.  It  is  in  this  cafe  decompofed 
with  a  rapidity  fo  much  the  greater,  as  the  oil  has  a  greater  af- 
finity with  the  oxigene.  On  this  account  it  is  that  the  inflam- 
mation of  the  drying  oils  is  more  eafily  effected  than  that  of  thd 
others. 

Thofe  acid's  whofe  conllituent  parts  adhere  mod  ftrongly  to- 
gether, have  but  a  very  feeble  action  on  oils  ;  a  circumftance 
which  proves  that  the  efFe<fl  of  acids  upon  oils  is  principally 
owing  to  the  combination  of  their  oxigene. 

It  is  by  virtue  of  this  ftrong  affinity  of  oils  with  oxigene,  that 
they  poffefs  the  power  of  reviving  metals.  The  oxigene  then 
quits  the  metal,  and  unites  with  the  oils,  which  become  thick 
and  coloured.  It  likewife  follows  from  hence  that  drying  oils 
ought  to  be  preferred  for  this  ufe  ;  and  we  find  that  pra£licc 
agrees  with  theory  in  this  refpe^fc. 

DIVISION    IL 

"Concerning  Volatile  Oils. 

Fixed  oil  is  combined  with  mucilage,  volatile  oil  with  the 
fpiritus  reftor,  or  aroma  ;  and  it  is  this  combination  or  mixture 
which  conftitutes  the  difference  betv/een  them.  The  volatile 
oils  are  characterized  by  a  ftrong  fmell,  more  or  lefs  agreeable  ;. 
they  are  foluble  in  alcohol,  and  have  a  penetrating  and  acrid 
tafte.  All  the  aromatick  plants  contain  volatile  oil,  excepting 
thofe  whofe  fmell  is  very  tranfient,  fuch  as  jeflamine,  violets, 
lilies,  &c. 

The  volatile  oil  is  fometimes  diftributed  through  the  whole 
plant,  as  in  the  Bohemian  angelica;  fometimes  it  exifls  in 
the  bark,  as  in  cinnamon.  Balm,  mint,  and  the  greater  abfin- 
thium,  contain  their  oils  in' the  flem  and  leaves  ;  elicampane, 
the  iris  of  Florence,  and  the  caryophyllata,   in  the  root.      AH 


Volatile  9r  EJfcntial  Oils,  435 

therefinous  trees  contain  it  in  their  young  branches  5  rofemary, 
thyme,  and  wild  thyme,  contain  their  eiTential  oils  in  their  leaves 
and  buds  j  lavender,  and  the  rofe,  in  the  calyx  of  their  flov^rers ; 
camomile,  lemon,  and  orange  trees,  in  the  petals.  Many  fruits 
contain  it  through  their  whole  fubltance,  fuch  as  pepper,  juni- 
per, &c.  Oranges  and  lemons  in  the  zeft  and  peeling  which 
inclofe  them.  The  feed  of  umbelliferous  plants,  fuch  as  annife 
and  fennel,  have  the  v^ficles  of  eiTential  oil  arranged  along  the 
proje£ling  lines  on  their  fK:in  :  the  nutmeg  tree  contains  its  eflen- 
tiai  oil  in  the  nut  itfelf. — See  UlntroduSlion  h  /'  Etude  du  Regne 
Veg.  par  M.  Buquet.  p.  209 — 2 1 2. 

The  quantity  of  volatile  oil  varies  according  to  the  ftate  of 
the  plant.  Some  afford  molt  when  green,  others  when  dry  ; 
but  the  latter  conftitute  the  fmallelt  number.  The  quantity 
likewife  varies  according  to  the  age  of  the  plant,  the  foil,  the 
climate,  and  the  time  of  extraftion. 

The  volatile  oils  likewife  differ  in  their  confiftcnce.  Some  arQ 
very  fluid,  as  thofe  of  lavender,  rofemary,  and  rue  ;  the  oils  of 
cinnamon  and  faffafras  are  thicker ;  there  are  fome  which  con* 
llantly  preferve  their  fluidity  :  others  which  become  concrete 
by  the  flightefl  impreflion  of  cold,  as  thofe  of  annlfted  and 
fennel :  others  again  poffefs  the  concrete  form,  fuch  as  tho 
Tofes,  of  parfley,  and  of  elicampane. 

The  volatile  oils  likewife  vary  in  their  colour.  The  01 
rofes  is  white  ;  that  of  lavender,  of  a  light  yellow :  that  of  cin- 
namon, of  a  brown  yellow ;  the  oil  of  camomile  is  of  a  fine 
blue  ;  that  of  millefoil,  of  a  fea-green  j  that  of  parflev,  green, 
&c.       r 

The  weight  is  likewife  different  in  the  different  kinds.  The 
oils  of  our  climates  are  in  general  Kght,  and  fwim  upon  water  ; 
others  are  nearly  of  the  fame  weight ;  and  others  are  heavier, 
fuch  as  the  oils  of  faffafras  and  of  cloves. 

The  fmells  of  effential  oils  vary  according  to  thofe  of  the 
plants  which  produce  them. 

The  tafte  of  the  volatile  oils  in  general  is  hot ;  but  the  tafle 
of  the  plant  does  not  always  influence  that  of  the  oil ;  for  ex- 
ample, the  oil  of  pepper  has  no  acrimony,  and  that  which  is 
obtained  from  wormwood  is  not  bitter. 

We  are  acquainted  with  two  methods  of  extra<n:ing  the  vola- 
tile oils — expreffion  and  diftillation. 

I.  Thofe  oils  which  are,  as  it  were,  in  a  naked  ftate,  and  con- 
tained in  projecting  and  vifible  receptacles,  are  obtained  by  ex- 
preffion. Such  are  thofe  of  citrons,  oranges,  cedrat,  and  berga- 
motte  ;  the  oil  iffucsout  of  the  fliin  of  thefe  fruits  when  prefled. 
it  may  therefore  be  procured  by  a  llrong  preffure  of  the  peeJin^ 


ana 


43  <^  Extraclion  of  Volatile  Oih, 

againft  an  inclined  glafs.  In  Provence  and  in  Italy  they  ar« 
rafped  j  by  which  means  the  veficles  are  torn,  and  the  oil  flows 
into  the  veffel  deftined  to  receive  it  :  this  oil  fuiFers  the  parenchy- 
ma which  goes  along  with  it  to  fubfide,  and  becomes  clear  by 
ftanding. 

If  a  lump  of  fugar  be  rubbed  againft  thefe  veficles,  it  imbibes 
the  volatile  oils  j  and  forms  an  olco-faccharum,  folubJe  in  water, 
and  very  proper  to  give  an  aromatick  flavour  to  certain  liquids. 

2.  Diitiiiation  is  the  method  moft  commonly  ufed  in  the  ex- 
tradion  of  volatile  oils.  For  this  purpofe,  the  plant  or  fruit 
which  contains  the  oil  is  placed  in  the  boiler  or  body  of  the 
alembick.  A  quantity  of  water  is  then  poured  in,  fufficient  to 
cover  the  plant,  and  the  water  is  heated  to  ebullition.  The  oil 
which  rifes  with  this  degree  of  heat,  comes  over  with  the  water, 
and  is  colle£ted  at  the  furface  in  a  particular  receiver,  called  the 
Italian  receiver,  which  fufters  the  furplus  of  water  to  efcape  by 
a  fpout  iflUing  from  the  belly  of  the  veflTel,  whofe  orifice  is  low- 
er than  tha»  of  the  neck  of  the  receiver  j  fo  that  by  this  means 
the  oil  is  colledfed  in  the  neck,  vyithout  a  poflibility  of  its  efr 
caping. 

The  water  which  pafles  over  in  diftillation    is  more    or  lefs 
jllljurged  with  oil,    and  the  odorant  principle   of  the  plant,  and 
^^HTs  what  is  known  by  the  name  of  Diflilled  Water.      Thefe 
^^Wers  ought  to  be  returned  again  into  the  cucurbit   when  the 
fame  kind  of  plant  is  again  diltilled  ;    becaufe,   being  faturated 
with  oil,   and  the  aromatick  principle,  they   contribute  to  aug- 
ment the  ulteriour  prod  u£l. 

When  the  oil  is  very  fluid  or  very  volatile,  it  is  neSeflary  to 
annex  a  worm  pipe  to  the  alembick,  and  to  have  the  precautiori 
of  keeping  the  water  at  a  very  cold  temperature  *,  but  when, 
on  the  contrary,  the  oil  is  thick,  the  worm  pipe  muft  be  remov- 
ed, and  the  water  of  the  refrigeratory  kept  at  a  moderate  tem- 
perature. In  the  firlt  way,  the  oils  of  balm,  mint,  fage,  laven- 
der, camomile,  &c.  may  be  diftilled  ;  and  by  the  fecond,  the  oils 
of  rofes,  of  elicampane,  of  parfley,  of  fennel,  of  cumin,  &c. 

The  oil  of  cloves  may  likewife  be  extracted  by  diftillation  per 
defcenfum,  which  is  determined  by  applymg  the  fire  above  the 
material. 

Volatile  oils  are  very  fubjecl  to  be  adulterated,  either  by  mix- 
ture with  fat  oils,  or  with  other  eflTential  oils,  fuch  as  that  of  tur- 
pentine, which  is  cheaper  *,  or  by  mixing  them  with  alcohol.  In 
the  firft  cafe  the  fraud  is  eafily  deteded — i.  By  diftillation,  be- 
caufe volatile  oils  rife  at  the  heat  of  boiling  water.  2.  By  cauf- 
mg  blotting  paper  to  imbibe  fome  of  the  mixture,  and  expofing 
it  to  a  degree  of  heat  fufiicient  to  drive  off  the  volatile  oil.     3. 


Properties  of  Volatile  Oils,  43 1 

]By  means  of  alcohol,  which  becomes  turbid  and  milky  by  the 
infolubility  of  the  fixed  oil. 

The  volatile  oils  which  have  a  veryftrongfmell,fuchasthofe  of 
thyme  and  lavender,  are  often  fophilticated  by  oil  of  turpentine. 
In  this  cafe  the  fraud  may  be  difcovered  by  foaking  a  fmall  piece 
of  cotton  in  the  mixture,  and  leaving  it  expofed  to  the  air  a  fuf- 
ficient  time  for  the  fmell  of  the  good  oil  to  be  diffipated,  and 
leave  only  that  of  the  adulteration.  The  fame  end  may  be  an- 
fwered  by  rubbing  a  fmall  quantity  of  the  mixture  on  the  hand, 
in  vi^hich  the  peculiar  fmell  of  oil  of  turpentine  is  developed. 
Thefe  oils  are  iikewife  falfified  by  digefting  the  plant  in  oil  of  ol» 
ive  before  diftillation,  In  this  manner  the  oil  of  camomile  is 
prepared. 

Tke  very  light  oils,  fuch  as  thofe  of  cedrat  or  bergamotte,  are 
often  mixed  with  a  fmall  quantity  of  alcohol.  This  fraud  is  ea- 
fily  detected  by  the  addition  of  a  few  drops  of  water,  which  im- 
mediately become  white,  becaufe  the  alcohol  abandons  the  oil 
jto  unite  with  the  water. 

The  volatile  oils  are  capable  of  uniting  with  oxigene,  with  al" 
kalis,  and  with  acids. 

1.  Volatile  oils  abfprb  oxigene  with  greater  facility  tlian  the 
fixed  oils.  They  become  coloured  by  the  abforption,  grqw 
thicker,  and  pafs  to  the  ftate  of  refin  ;  and  when  rhey  t^i 
thickened  to  this  point,  they  are  no  longer  capable  of  ferment- 
ing, but  fecure  from  all  putrefadlion  fuch  bodies  as  are  pene- 
trated and  well  impregnated  with  them.  On  this  is  founded  the 
theory  of  embalming. — The  action  of  acids  upon  thefe  oils,  cau- 
fes  them  to  pafs  to  the  flate  of  refm  ;  and  there  is  no  other  dif- 
ference between  volatile  oil  and  refin,  than  that  which  arifes 
from  this  addition  of   oxigene. 

All  the  oils,  when  they  aflume  the  charatfler  of  refin  by  this 
combination  of  oxigene,  let  fall  needle-formed  cryftals  of  cam^. 
phor.  Mr.  Geoffroy  has  oblerved  them  in  the  oil  of  fever-few, 
marjoram,  and  turpentine.     Acad.  1721,  p.  163. 

When  the  oil  is  changed  by  the  combination  of  oxigene,  it 
gradually  loles  its  fmell  and  volatility.  To  reftore  this  oil  tQ 
its  original  fi:ate,  it  is  diftilled.  A  thick  matter  remains  in  the 
didilling  veflel,  which  confiits  of  refm  perfedly  formed  and  is 
thus  feparated  from  the  oil,  which  has  not  yet  undergone  the 
iame  alteration. 

2.  The  habitudes  of  acids  are  not  the  fame  with  all  volatile 
oils.  1.  The  concentrated  fulphurick  acid  thickens  them  :  but, 
if  it  be  diluted,  it  forms  favonules.  2.  The  nitrick  acid,  when 
cx>ncentrated,  inflames  them  j  but,  when  diluted,  it  caufes  them 
gradually  to  pafs  to  the  itare  of  refin.      Borri<;hiu6  appears   to 


^3if  '  Camphor. 

Iiavcbeen  the  firfl;  who  inflamed  oil  of  turpentine  with  the  fiQ.- 
phurick  acid,  without  the  nitrick  acid.  Homberg  repeated  this^ 
^ehcate  experiment  with  the  other  volatile  oils.  The  inflamma- 
tion of  'oils  is  fo  much  the  more  eafiiy  eiFetled,  as  the  oil  is^ 
pjorc  drying  or  greedy  of  oxigene,  and  the  acid  more  eafiiy  de- 
compofed.  3.  The  muriatick  acid  reduces  oils  to  the  faponace- 
OUS  ft  ate,  but  the  oxigenated  muriatick  acid  thickens  them. 

3.  Starkey  appears  to  have  been  one  of  the  hrft  who  at- 
tempted to  combine  a  volatile  oil  with  a  fixed  alkali.  His  pro- 
cefs  is  long  and  complicated,  like  thofe  of  the  alchemlds ;  and 
the  combination  it  afforded  was  known  by  the  name  of  Starkey's 
Soap ;  the  procefs  of  this  chemift  was  fo  long  merely  becaufe 
he  ufed  the  carbonate  of  pot-a(h,  or  mild  vegetable  alkali ;  but 
if  ten  parts  of  cauftick  alkali,  or  lapis  cauftkus,  be  triturated  hot 
with  eight  parts  of  oil  of  turpentine,  the  foap  is  initantaneoufly 
formed,  and  becomes  very  hard.  This  is  the  procefs  of  Mr, 
Geoffroy.— Acad,  des  Sciences,  ami.  1725. 


Concerning  Camphor. 

Camphor  is  obtained  from  a  fpecies  of  laurel  which  grows  in, 
China  and  Japan.  Some  travellers  affirm  that  the  old  trees, 
contain  it  fo  abundantly,  that  on  fpUtting  the  trunk  it  is  found 
in  large  tears,  fo  pure  as  to  have  no  need  of  reftification.  To 
cxtra6t  the  camphor,  the  roots  of  the  trees  are  ufually  chofen  j 
oj-j  in  want  of  tbefe,  ail  the  other  parts  of  the  tree.  Theie  are 
put,  together  with  water,  into  an  iron  alembick, which  is  covered 
with  its  head.  The  capital  is  fitted  up  internally  with  cords  of 
rice  flraw,  the  joinings  are  luted,  and  the  diltillation  proceeded 
upon.  Part  of  the  camphor  fubiimes,  and  attaches  itfelf  to  the 
ftraw  within  the  head  j  while  another  portion  is  carried  into 
the  receiver  with  the  water.  The  Hollanders  purify  camphor 
by  mixing  an  ounce  of  quick-lime  with  every  pound  of  the  fub- 
Iknce,  and  fubliming  it  in  large  glafs  vefleis. 

Camphor,  thus  purified,  is  a  white  concrete  cryftalline  fub- 
ftance,  of  a  ftrong  fmell  and  tafte,  foluble  in  alcohol,  burning 
with  a  white  flame,  and  leaving  no  refidue  :  refembling  volatile 
oils  in  many  refpec^s,  but  differing  from  them  in  certain  proper- 
ties }  fuch  as  that  of  burning  without  a  refidue  \  of  difTolving 
quietly,  without  decompofition  or  alteration,  in  acids  ;  and  of- 
being  volatilized  by  a  gentle  heat,  without  change  of  its  nature. 

Camphor  is  obtained  by  diftillation  from  the  roots  of  zedoa- 
ry,  thyme,  rofemary,  lage,  the  inula  helenium,  the  anemony, 
the  paicjue  flower  or  puUatilla^  &c.      And  it  is  to  be  obferved, 


Properties  of  Camphor.  ^'^ 

t!iat  all  thefe  plants  afford  a  much  greater  quantity  of  camphor 
when  the  fap  has  been  fuffered  to  pafs  to  the  concrete  (late,  by 
a  deficcatlon  of  feveral  montlis.  Thyme  and  peppermint,  flow- 
ly  dried,  aiford  much  camphor  ;  whereas  the  frefh  plants  afford 
volatile  oil  :  rnofl  of  the  volatile  oils,  in  pafling  to  the  flate  of 
refin,  alfo  let  fall  much  camphor.  Mr  Achard  has  likewife  ob- 
ferved  that  a  fmell  of  camphor  was  difengaged  when  he  treated 
the  volatile  oil  of  fennel  with  acrds.  The  combination  of  the 
diluted  nitrick  acid  with  the  volatile  oil  of  anife,  afforded  him 
a  large  quantity  of  cryflals,  which  poffeffed  mofl  of  the  proper- 
ties of  camphor.  He  obtained  a  fimilar  precipitate  by  pouring 
the  vegetable  alkali  upon  vinegar  faturated  with  the  volatile  oil 
of  angelica. 

From  all  thefe  fafts,  it  appears,  that  the  bafe  of  camphor 
forms  one  of  the  conftituent  principles  of  fome  volatile  oils  ;  but 
it  is  in  the  liquid  (late,  and  does  not  become  concrete  but  by- 
combining  with  oxigene. 

Camphor  is  capable  of  cryftallization,  according  to  Mr  Ro- 
mieu,  whether  In  fublimation,  or  when  it  is  flowly  precipitated 
from  alcohol,  or  when  alcohol  is  fuperfaturated  with  it  -,  it  pre- 
cipitates in  llender  filaments,  cryftallizes  in  hexagonal  blades  at- 
tached to  a  common  axis,  and  it  fublimes  in  hexagonal  pyra- 
mids or  in  polygonal  cryflals. 

Camphor  is  not  foluble  in  water  ;  but  it  communicates  its 
fmell  to  that  fluid,  and  burns  on  its  furface.  Romleu  has  ob- 
ferved  that  fmall  pieces  of  camphor,  of  one  third  or  one  fourth 
of  a  line  in  diameter,  being  placed  on  the  furface  of  puje  water 
in  a  glafs,  have  a  rotatory  motion  :  and  this  appears  to  be  an 
eletftrical  phenomenon  ;  for  the  motion  ceales  if  the  water  be 
touched  with  a  conducting  fubftance  ;  but  continues  if  it  be 
touched,  with  an  infulating  body,  fuch  as  glafs,  fulphur,  or  re- 
fin.  Bergen  has  obferved  that  camphor  does  not  turn  upo»" 
hot  water. 

Acids  diffolve  camphor  without  producing  any  alteration  in 
It,  or  becoming  themfelves  decompofed  :  the  nitrick  acid  dlf- 
folves  it  quietly  ;  and  this  folution  has  been  called  Oil  of  Cam- 
phor. Camphor  precipitated  from  its  folution  in  acids  by  the 
addition  of  alkalis,  is  heavier,  harder,  and  much  lefs  combufti- 
ble,  according  to  the  experiments  of  Mr.  Kofegarten.  By  dif- 
tilling  the  nitrick  acid  feveral  times  from  this  fubftance,  it  ac- 
quires all  the  properties  of  an  acid  which  cryftallizes  in  parallel- 
opipedons.  To  obtain  the  camphorick  acid,  nothing  more  i$ 
required  than  to  didilthe  acid  at  feveral  times  from  the  cam- 
phor, and  in  a  large  quantity.  Mr.  Kofegarten  diftilled  the  ni- 
trick acid  eight  times  from  camphor,  andobta.ined  a  fait  cryftal- 


44®  ^S^^i  ^^'  ^f  Camphor* 

lized  in  parallelopipedons,  which  reddened  the  fyrup  of  violeti^ 
and  the  tin£lure  of  turnfole.  Its  tafte  its  bitter  \  and  it  differs 
from  the  oxalick  acid  in  not  precipitating  Hme  from  the  muri- 
atick  acid. 

With  pot-afli  it  forms  a  fait  which  cryftallizes  in  regular  hex-* 
agons. 

With  foda  it  affords  irregular  cryflals. 

With  ammoniack  it  forms  cryftalline  maffes,  which  exhibit 
cryftals  in  needles  and  in  prifms. 

With  magnefia  it  produces  a  white  pulverulent  fait,  which 
may  again  be  dilTolved  in  water. 

It  dilTolves  copper,  iron,  bifmuth,  zinc,  arfenick,  and  cobalt. 
The  folution  of  iron  affords  a  yellowiili  white  powder,  which  is 
infoluble. 

This  acid  forms,  with  manganefe,  cryftals  whofe  planes  aire 
parallel,  and  in  fome  refpe6ts  refemble  bafaltes. 

The  camphorick  acid,  or  rather  the  radical  of  this  acid,  exiftai 
in  feveral  vegetables  ;  fince  camphor  may  be  extra£ted  from  the 
oils  of  thyme,  of  cinnamon,  of  turpentine,  of  mint,  of  feverfew, 
of  faffafras,  &c.  Mr.  Dehne  has  obtained  it  from  the  pafque 
ilower,  or  pulfatilla  ;  and  Cartheufer  has  indicated  feveral  other 
plants  which  contain  it. 

Alcohol  readily  diffolves  it,  and  it  may  be  precipitated  by  wa- 
ter alone  :  this  folution  is  known  in  pharmacy  by  the  name  of 
Camphorated  Spirit  of  Wine,  or  Camphorated  Brandy,  whea 
brandy  is  the  folvcnt. 

The  fixed  and  volatile  oils  likewife  diffolve  each  other  by  the 
afliftance  of  heat  ;  the  folutions  let  fall  cryftals  in  vegetation, 
fimilar  to  thofe  which  are  formed  in  the  folutions  of  fal-ammo- 
niack,  compofed  of  very  fine  filaments  adhering  to  a  middle 
part.  This  obfervation  was  made  by  Mr.  Romieu.  Acad,  ded 
Sciences,  1756. 

Camphor  is  one  of  the  beft  remedies  which  the  art  of  medi- 
cine poffeffes.  When  applied  to  inflammatory  tumours,  it  is  re- 
folvent  -,  and,  internally  taken,  it  is  antifpafmodick,  efpecially 
when  diffolved  in  brandy.  It  is  given  in  Germany  and  in  En- 
gland in  the  dofe  of  feveral  drams  per  day  ;  but  in  France  our 
timid  phyficians  do  not  prefcribe  it  in  a  larger  dofe  than  a  few 
grains.  It  mitigates  heat  in  the  urinary  paffage.  It  is  givei^ 
triturated  with  yolk  of  egg,  fugar,  &c. 

It  has  likewife  been  fuppofed  that  its  fmell  deftroyed  or  drove 
away  moths,  and  other  infedts  which  feed  upon  cloth,  Sec. 


RefitiQUS  Suhfianofs, 


ARTICLE     IIL 


44^ 


Concerning  Refins. 

The  name  of  Rcfin  is  ufed  to  denote  inflamma&lc  fubftancct 
foluble  in  alcohol,  ufually  affording  much  foot  by  their  combuft^ 
ion  ;  they  are  likewife  foluble  in  oils,  but  not  all  in  water. 

All  the  refins  appear  to  be  nothing  elfe  but  oils  rendered 
concrete  by  their  combination  with  oxigene.  The  expofure  of 
thefe  to  the  open  air,  and  the  decompofition  of  acids  applied  to 
them,  evidently  prove  this  conclufion. 

Refms  in  general  are  lefs  fweet  than  the  balfams.  They  af- 
ford more  volatile  oil,  but  no  acid  by  diftilfation. 

There  are  fome  among  the  known  refins  which  are  very  pure 
and  perfectly  foluble  in  alcohol,  fuch  as  the  balm  of  Mecca  and 
of  Copahu,  turpentines,  tacamahaca,  elemi  :  others  are  lefs 
pure,  and  contain  a  fmall  portion  of  extract,  which  renders 
them  not  totally  foluble  in  alcohol  j  fuch  are  maftick,  fandarach 
guaiacum,  laudanum,  and  dragon's  blood. 

1.  The  balfam  of  Mecca  is  a  fluid  juice  which  becomes  thick 
and  brown  by  age.  It  flows  from  incifions  made  in  the  amyris 
opobalfamum.  It  is  known  by  the  different  names  of  Balm  o£ 
Judea,  of  Egypt^  of  Grand  Cairo,  of  Syria,  of  Conftantinople, 
&c. 

Its  fmell  Is  flrong,  and  inclining  to  that  of  lemons  ;  its  tafl:« 
is  bitter  and  aromatick. 

This  balfam,  diftiiled  by  the  heat  of  boiling  water,  affordg 
much  volatile  oil, 

it  is  balfamick  ;  and  Is  given  incorporated  with  fugar,  or 
mixed  with  the  yolk  of  egg.  It  is  aromatick,  vulnerary,  and 
healing. 

2.  The  balfam  of  Copahu  flows  from  a  tree  called  Copaiba 
in  South  America,  near  Tolu.  It  affords  the  fame  produifls, 
and  pofTeffes  the  fame  virtues,  as  the  foregoing. 

3.  The  turpentine  of  Chios  flows  from  the  turpentine  tree, 
which  affords  the  piffachios.  It  is  fluid,  and  of  a  yellowifh 
white  colour  inclining  to  blue. 

This  plant  grows  in  Cyprus,  at  Chios,  and  is  common  in  the 
fouth  of  France.  The  turpentine  is  obtained  only  from  the 
trunk  and  large  branches.  Incifions  are  made  firfl  at  the  low- 
er parts  of  the  tree,  and  afterwards  by  degrees  higher  up. 

This  turpentine,  diftiiled  on  the  water-bath,  without  addition 
aflrbrds  a  very  white,  very  limpid,  and  very  fragrant  volatile  oil : 
a  more  ponderous  oil  may  be  extrad"led  at  the  heat  of  boifing 
water  ;  and  the  refidue  which  is  called  Boiled  Turpentine,  af- 


44 i  yarious  Refmous  Suhftaticer, 

fords  by  diftillation,  in  the  reverberatory  furnace,  a  weak  acid^a 
fmall  quantity  of  brown  confirtent  oil,  and  much  coal. 

The  turpentine  of  Chios  is  very  rare  in  commerce.  Venice 
turpentine  is  extracted  from  the  larix  :  its  colour  is  a  bright 
yellow,  its  confidence  limpid,  its  fmell  ftrong  and  aromatick, 
and  its  tafte  bitter. 

The  tree  which  aflbrds  it  is  tliat  wliich  affords  manna.  Holes- 
are  bored  during  the  fummer  near  the  bottom  of  the  trunks  of 
thefe  trees,  into  which  fmall  gutters  or  tubes  are  inferted,  to 
convey  the  juice  into  vefiels  intended  to  receive  it.  The  refin 
is  obtained  only  from  trees  in  full  vigour  ;  the  old  trees  very 
often  have  confiderable  depoGtions  of  refin  in  their  trunks. 

This  turpentine  affords  the  fame  principles  as  that  of  Chios. 

It  is  ufed  in  medicine  as  a  detergent  for  ulcers  in  the  lungs,- 
kidneys,  &c.  either  incorporated  with  fugar,  or  mixed  with  the 
yoik  of  an  egg  to  render  it  more  mifcible  with  aqueous  potions. 
The  foap  of  Starky,  which  we  have  fpcken  of  under  the  article 
of  Volatile  Oils,  is  made  with  this  turpentine. 

The  refin  known  in  commerce  by  the  name  of  Strafburgh 
Turpentine,  is  a  rcfinous  juice  of  the  confidence  of  a  fixed  oil,, 
of  a  yellowifli  white  colour,  a  bitter  tafle,  and  a  more  agreeable 
fmeli  than  the  preceding  refins. 

It  flows  from  the  yew-leaved  fir,  which  is  very  common  in 
the  mountains  of  Switzerland.  This  refin  is  collefted  in  blift- 
ers,  which  appear  beneath  the  bark  in  the  ftrong  heats  of  fum- 
mer. The  peafants  pierce  thefe  veficles  with  the  point  of  a 
fmall  horn,  which  becomes  filled  with  the  juice,  and  is  from 
time  to  time  emptied  into  a  larger  vefi^el. 

The  balm  of  Canada  difi^ers  from  the  turpentine  of  the  fir  in 
Its  fmell  only,  which  is  more  pleafant.  It  is  obtained  from  a 
fpecies  of  fir  which  grows  in  Canada, 

Oil  of  turpentine  is  more  particularly  ufed  In  the  arts.  It  Is 
the  great  folvent  for  all  refms  ;  and,  as  it  evaporates,  it  leaves 
them  applied  to  the  furface  of  bodies  on  which  the  mixture  has 
been  fpread.  As  refins  are  the  bafis  of  all  varnifiies,  alcohol  and 
oil  of  turpentine  muft  be  the  vehicles  or  foivents. 

4.  Pitch  is  a  refinous  juice  of  a  yellow  colour,  more  or  lefs: 
inclining  to  brown.  It  is  afforded  by  a  fir  named  Picea  or  E- 
picea.  Incifions  are  made  through  the  bark  ;  and  the  wound 
is  renewed  from  time  to  time,  as  the  lips  become  callous.  A 
vigorous  tree  often  affords  forty  pounds. 

Pitch  melted,  and  cxprefied  through  bags  of  cloth,  is  render- 
ed purer.  It  is  packed  in  barrels,  by  the  name  of  White  Pitch;, 
or  Burgundy  Pitch. 

White  pit^h  mixed  with  lamp  black,  forms  black  pitchy 


Various  Reftnous  Subjfances,  443 

White  pitch  kept  in  fufion  becomes  dry.  The  deficcation 
may  be  facilitated  with  vinegar,  and  leaving  it  for  a  time  over 
the  fire.     It  then  becomes  very  dry,  and  is  called  Colophony. 

Lamp-black  is  the  foot  of  burned  pitch.  It  is  likewife  pre- 
pared by  colle<fting  the  foot  of  pit-coal. 

5.  Gallipot  is  a  concrete  refmous  juice,  of  a  yellowifli  white 
colour  and  ftrong  fmell.  This  juice  comes  from  Guienne, 
where  it  is  afforded  by  two  fpecies  of  pine,  the  pinus  maritima 
.major,  et  minor. 

When  thefe  trees  have  acquired  a  certain  fize,  a  holeornotch 
is  cut  through  the  bark,  near  the  bottom  of  the  trunk.  The 
refni  iflues  out,  and  flows  into  vefleis  placed  beneath  to  receive 
it.  Care  is  taken  to  keep  the  wound  open,  and  to.  renew  it. 
The  refm  flows  during  the  Turn mer  \  but  that  which  ifliies  out 
-during  the  fpring,  autumn,  and  winter,  dries  againft  the  tree. 

The  Pine  likewife  afl-brds  tar,  and  the  oil  called  huile  de  Cade, 
Por  this  purpofe  the  wood  ^  the  trunk,  branches,  and  roots,  is 
heaped  together  and  covered  with  turf,  over  which  a  fire  is 
lighted,  as  if  to  convert  them  into  charcoal.  The  oil  which  m 
difcngaged,  not  being  at  liberty  to  cfcape,  falls  to  the  bottom  in- 
to a  channel  or  gutter,  which  convevs  it  into  a  tub.  The  moil 
iluid  part  is  fold  under  the  name  of  huile  de  Cade  ;  and  the 
the  thicker  part  is  the  tar  ufed  for  paying  or  painting  the  parts 
of  fliipping  and  other  vefiels. 

The  combinations  of  feveral  refins,  coloured  by  cinnabar  and 
minium  forms  fealing-wax.  To  make  the  wax,  take  half  an 
ounce  of  gum-lac,  two  drams  of  turpentine,  the  fame  quantity 
of  colophony,  one  dram  of  cinnabar,  and  the  fame  quantity  of 
minium.  The  lac  and  and  the  colophony,  are  to  be  firfl:  fufcd, 
after  v/hlch  the  turpentine  is  to  be  added,  and  laftly  the  colour- 
ing matters. 

6.  Maftick  has  the  form  of  white  tears  of  a  farinaceous  ap- 
pearance, having  little  fmell,  and  a  bitter  aitringent  tafte.  Maf- 
tick flows  naturally  from  the  tree,  but  its  produce  is  accelerated 
by  incifions.  The  lefier  turpentine  tree,  and  the  lentifcus,  af- 
ford that  which  is  met  with  in  commerce. 

Maitick  aflx)rds  no  volatile  oil  when  dillilled  with  water.  It 
is  almoil  totally  foiuble  in  alcohol. 

This  refin  is  ufed  in  fumigations.  It  is  chevv^ed,  to  ftrength- 
en  the  gums  j  and  it  forms  the  bafis  of  feveral  drying  var- 
nilhes. 

7.  Sandarachis  a  concrete  refmous  juice,  in  dry  white  tranf- 
parent  tears,  of  a  bitter  and  aftringent  taite.  It  is  obtained 
from  moil  fpecies  of  the  juniper,  and  is  found  between  the  bark 
and  the  wood. 


444  Balfams. 

Sanclarach  is  almoft  totally  folub'c  in  alcohol,  with  which  i# 
forms  a  very  white  varnifh,  that  dries  fpeedily.  For  this  reafon, 
the  refm  itfelf  is  known  by  us  under  the  name  of  Varnilhj 
(vernis.J 

8.  Labdanum  is  a  black  refinous  juice,  dry  and  friable,  of  a 
ftrong  fmell,  and  a  difagreeable  aromatick  tafte.  It  tranfudes 
from  the  leaves  and  branches  of  a  kind  of  ciftus,  which  grows 
in  the  ifland  of  Candia.  Tournefort,  in  his  Voyage  to  the  Le- 
vant, informs  us  that  when  the  air  is  dry,  and  the  refin  iffues 
out  of  the  pores  of  the  ciftus,  the  peafants  ftrike  all  the  parts  of 
thefe  trees  with  a  kind  of  whip,  made  with  feveral  thongs  of 
leather,  fixed  to  the  end  of  a  ftafF.  The  juice  adheres  to  the 
leather,  and  is  cleared  off  with  a  knife.  This  is  pure  labdanum, 
and  is  very  rare.  That  which  is  known  by  the  name  of  labda- 
num in  tortisy  is  mixed  with  a  very  fine  ferruginous  fand,  for  the 
purpofe  of  increafing  its  weight. 

9.  Dragon's  blood  is  a  refin  of  a^eep  red  in  the  mafs,  but 
brighter  when  in  powder.     It  has  neither  taftc  nor  fmell. 

It  is  obtained  from  the  drakena^  in  the  Canary  iflands,  from 
v.aiich  it  flows  in  tears  during  the  dog-days.  It  is  alfo  obtained 
from  the  petro-carpus  draco.  The  parts  are  expofed  to  the  va- 
pour of  hot-water  ;  the  juice  iflues  out  in  drops,  which  are  col- 
le£led  and  wrapped  up  in  the  leaves  of  reeds. 

The  dragon's  blood  of  the  fhops,  which  has  the  form  of  flat- 
tened orbicular  loaves,  is  a  compofition  of  various  gums,  to 
which  this  form  is  given,  after  they  have  been  coloured  with  a 
fniall  quantity  of  dragon's  blood. 

Dragon's  blood  is  foluble  in  alcohol  :  the  folution  is  red  ;  the 
refin  itfelf  may  be  precipitated  of  the  fame  colour* 

This  refin  is  ufcd  in  medicine  as  an  aftringent. 

ARTICLE    IV. 

Concerning  Balfams. 

Some  authors  define  balfams  to  be  fluid  inflammable  fubflan- 
pes  ;  but  there  are  fome  which  are  dry.  Others  again  give  thi^ 
ijame  to  the  mod  fragrant  among  the  refins.  M.  Bucquet  has 
confined  this  denomination  to  fuch  refins  only  as  have  a  fv/eet 
flavour,  capable  of  being  communicated  to  water  j  and  which 
more  efpecially  contain  fragrant  acid  and  concrete  falts,  M'hich 
may  be  feparated  by  deco£lion  or  fubllmation.  It  appears 
therefore  that  thefe  fubftances  contain  a  principle  not  found  in 
refins,  which,  combining  with  oxigene,  forms  an  acid  ;  while 
t\it  oil,  fatm-ated  with  the  fame  air,  forms  the  refin.     This  acid 


Varieties  of  Benzom»  ^^^ 

fclt  is  folublc  in  water  and  alcohol.  As  the  chemical  analyfis 
points  out  a  fufficiently  ftriking  difFerence  betv/een  balfams  and 
■reGns,  we  think  it  proper  to  treat  them  feparately. 

The  fubftanccs  called  Balfams  are  therefore  refins  united  with 
a  concrete  acid  fait.  We  are  acquainted  with  three  principal 
kinds  ;  viz.  benzoin,  the  balfam  of  Tolu,  and  the  ftorax  cal- 
amita. 

I.  Benzoin  is  a  coagulated  juice,  of  a  pleafant  fragrant  fmell^ 
which  becomes  ftronger  by  friction  and  heat. 

Two  varieties  of  this  fubllance  are  known  ;  the  benzoe  amyg* 
daloides,  and  the  common  benzoin*  The  firft  is  compofed  of 
the  mod  beautiful  tears  of  this  balfam,  connected  together  by  ^ 
gluten  of  the  fame  nature,  but  browner,  and  of  the  afpedt  of 
nutmegs  in  its  fradture.  The  fecond  is  merely  the  juice  itfelf, 
without  any  mixtuj^e  of  thefe  fine  and  very  pure  tears.  It  comes 
to  us  from  the  kingdom  of  Siam,  and  the  illand  of  Sumatra  j 
but  we  do  not  know  the  tree  that  aftbrds  it.* 

Benzoin  laid  upon  hot  coals,  fufes,  fpeedily,  takes  fire,  and  e- 
mlts  a  ftrong  aromatick  fmell.  But  if  it  be  merely  heated,  with- 
out fetting  it  on  fire,  it  fv,'ell3  up,  and  emits  a  more  pleafant 
tliough  lefs  powerful  fmell. 

Benzoin  pounded,  and  boiled  in  water,  affords  an  acid  fait, 
which  cryftallizes  in  long  needles  by  cooling.  This  fait  may 
alfo  be  extracted  by  fubUmation.  It  rifes  by  a  degree  of  heat 
even  lefs  than  that  which  is  required  to  raife  the  oil  of  benzoin  ; 
and  this  is  the  fubftance  called  Flovirers  of  Benzoin,  or  the  Sub- 
limed acid  of  Benzoin.  Neither  of  thefe  procefies  are  econom- 
ical ;  and  in  the  preparation  of  thefe  articles,  in  the  large  way, 
I  begin  by  diftilling  the  benzoin,  and  caufe  all  the  produdls  to 
pafs  confounded  together  into  a  capacious  receiver.  I  then 
boil  the  produft  in  water,  and  by  this  means  I  obtain  a  much 
greater  quantity  of  the  fait  of  benzoin  :  becaufe,  in  this  ttate, 
ihe  water  attacks  and  diilblves  the  whole  contents  ;  whereas  the 
mofl  accurate  trituration  will  not  produce  the  fame  effect. 

The  fublimed  acid  of  benzoin  has  a  very  penetrating  aromat- 
ick fmell,  which  excites  coughing  j  more  efpccially  if  the  fub- 
limlng  vefTels  be  opened  while  yet  hot.  It  reddens  the  fyr- 
up  of  violets,  and  efrcrvefces  with  the  alkaline  carbonates.  It 
unites  with  earths,  alkalis,  and  metals,  and  forms  benzoates* 
of  which  Bcrgmann  and  Scheele  have  given  us  fome  account. 

Alcohol  dilfolves  benzom  totally,  without  leaving  any  reliduc 
but  fuch  foreign  impurities  as  the  balfam  may  happen   to  con- 

*  For  a  drawing  and  defcript'on  of  thi?  tree,  co  ofult  Dryander,  in  tlic 
rlul.  Ttanf  vol,  IxxvJi.I^p.  31. 


44^  Balfam  of  To!u.     Storax  or  Styra^*      ^'^ 

tairt.     It  may  be  precipitated  by  the  addition  of  water  ;  and  thtii 
Conftitutes  the  opaque  fluid  called  Lac  Virginale. 

Benzoin  is  ufed  as  an  aromatick  in  medicine  ;  but  it  is  fel- 
dom  ufed  in  fubftance,  becaufe  of  its  fparing  foiubility  :  its  tinc- 
ture, and  volatile  acid  are  ufed.  The  latter  is  a  good  incifive 
medicine  to  be  adminiftered  in  pituitous  obftru6lions  of  the 
iungs,  the  kidneys,  &c.  It  is  given  in  extracts,  or  diffolved  in 
water. 

Benzoin  is  employed  in  fumigations  for  indolent  tumours. 
The  oil  is  likewife  an  excellent  refolvent.  It  is  applied  by  fric- 
tion to  members  afFe<fted  with  cold  rheumatick  and  paralytick 
difqrders. 

2.  The  balfam  of  Tolu,  of  Peru,  or  of  Carthagena,  has  a  mild 
and  plcafant  fmell. 

It  is  met  with  in  commerce  in  two  different  forms  ;  either  in 
fhelis  or  in  the  fluid  ftate.  The  coco  is  foftencd  in  boiling 
water,  and  the  balfam  flows  out  in  the  fluid  form. 

The  tree  which  affords  it,  is  the  Toluifera  of  Linnxus.  It 
grows  in  South  America,  in  the  diftridl  called  Tolu,  between 
Carthagena  and  Nombre  de  Dios. 

The  fluid  balfam  aflbrds  much  volatile  oil  when  diftilled  by 
the  heat  of  boiling  water. 

An  acid  fait  may  be  extra6led  from  this  balfam,  which  great- 
ly refembies  that  of  benzoin  ;  and  may  be  obtained  by  the  fame 
procefles;  but  this  fublimed  fait  is  commonly  brown, becaufe  it 
is  fbiled  by  a  portion  of  the  balfam,  which  rifes  with  a  Icfs  heat 
than  benzoin  does. 

This  balfam  is  foluble  in  alcohol,  and  may  be  precipitated  by 
the  addition  of  water. 

It  is  much  ufed  in  medicine,  as  an  aromatick,  vulnerary,  and 
antiputrefcent  remedy.  It  is  adminiilered  either  trituraied  with 
fugar,  or  mixed  with  fome  extract.  A  fyrup  is  prepared  from 
it  by  digefting  it  in  a  gentle  heat  with  fugar  ;  oi-  by  diffolvingit 
in  alcohol,  adding  fugar,  and  fuffering  the  alcohol  to  diflipate 
fpontaneoufly. 

It  is  falfihed  by  macerating  the  didilled  oil  of  benzoin  upon 
the  buds  of  the  balm-feented  poplar,  and  adding  a  fmali  quanti- 
ty of  the  natural  balfam. 

Storax  or  ftyrax  calamita  js  a  juice  of  a  very  (trong  but  plea- 
fant  Imell.  Two  varieties  are  known  in  commerce  :  the  one 
in  rfeddifli  clean  tears ;  the  other  in  maffcs  of  a  biackifli  red  col- 
our, f6ft  and  fatty. 

The  plant  which  affords  it  is  called  the  oriental  liquid  am- 
bfer.  It  has  been  long  fuppofed  to  be  the  ftyrax  folio  mali  co- 
tona^i  C.  B.  which  is  known  in  Provence,  in  the  wood  of  La 


Baifams,      Gum  Rejirts,  j^j^j 

Chatreufe  de  Montrieu,  by  the  name  of  Aliboufier  ;  and,  ac- 
cording to  Duhamel,  affords  a  very  odorant  juice,  which  he  took 
for  ilorax. 

Its  habitudes  during  analyfis  are  the  fame  as  the  prece4ing 
and  it  exhibits  the  fame  phenomena. 

It  was  formerly  brought  to  us  in  canes  or  reeds>  whence  its 
name  of  itorax  calamita. 

Thefe  three  balfams  form  the  bafe  of  thofe  fragrant  paftils 
which  are  burned  in  the  chambers  of  the  fick,  to  conceal  or  dif- 
guife  bed  fmells.  Thefe  balfams  are  made  into  raafles  by  means 
of  gum  ;  with  the  addition  of  charcoal  and  the  nitrate  of  pot- 
iaih,  to  facilitate  combuflion. 

ARTICLE    V. 

Concerning  Gum  Refins. 

The  gum  refins  are  a  natural  mixture  of  extra£i^  and  refin. 
They  feldom  flow  naturally  from  plants,  but  iffue  out  from  in- 
cifions  made  for  that  purpofe.  They  are  fometimes  white,  as  in 
the  tithymalus  and  the  fig-tree  ;  fometimes  yellow,  as  in  the 
chelidonium  :  fo  that  we  may  confider  thefe  fubftances  as  true 
cmulfions,  whofe  conftituent  principles  vary  in  their  propor- 
tions. 

The  gum  refins  are  partly  foluble  in  water,  and  partly  in 
alcohol. 

One  character  of  gum  refins  is,  that  they  render  water  turbid 
in  which  they  are  boiled. 

This  clafs  is  fufficiently  numerous  :  but  we  (hall  only  treat  of 
the  principal  fpecies,  and  more  efpecially  thofe  which  are  ufed 
in  medicine. 

I.  Olibanum,  or  frankincenfe,  is  a  gum  refin,  in  tears  of  a 
yellowifli  white  colour  and  tranfparent.  Two  kinds  are  known 
in  trade  :  the  male  incenfe,  in  fmall  very  pure  tears  ;  and  tlie  fe* 
male  incenfe,  in  large  and  impure  tears. 

The  tree  which  affords  it  is  not  known.  Some  authors  fup- 
pofe  it  to  be  the  cedar  v/ith  cyprefs  leaves. 

Olibanum  contains  three  parts  of  refinous  matter,  and  one 
of  extract.  When  it  is  boiled  in  water,  the  folution  is  white 
and  turbid,  like  that  of  all  the  juices  of  this  clafs.  When  it  is 
frefh,  it  affords  a  quantity  of  volatile  oil. 

Olibanum  is  ufed  in  medicine  as  a  refolvent.  But  its  chief 
ufe  is  in  our  temples,  where  it  has  been  adopted  as  one  of  the 
inltruments  of  worffiip  of  the  Divinity. 

It  is  ufed  in  hofpitals,  to  difguife  the  fmell  of  the  putrid  air 
which  is  exhaled.    M.  Achard  has  pyov^d  tliat  this  proceeding 


44^  Zeamtmn'j,     Gum  Gutiai,  w 

has  no  other  cfFe£t  than  that  of  deceiving  the   fenfe   of  fmeih 
ing. 

2.  Scammony  is  of  a  blackifli  grey  colour,  a  bitter  and  acrid 
tafte,  and  a  ftrong  naufeous  fmelL 

Two  varieties  are  met  with  in  commerce  ;  one  of  which 
comes  from  Aleppo,  and  the  other  from  Smyrna.  The  firll  is 
paler,  lighter,  and  more  pvare  ;  the  fecond  is  black,  heavy,  and 
mixed  with  foreign  fubftances. 

It  is  extraded  from  the  convulvulus  fcammonia,  principally 
from  the  root.  For  this  purpofe  incifions  are  made  at  the  head 
of  the  root :  it  is  coUeded  in  mufcle  fliells.  But  mofl  of  that 
met  with  in  trade  is  obtained  from  the  roots  by  expreflion. 

From  the  refults  of  the  analyfis  of  GeofFroy  and  Cartheufer, 
it  appears  that  the  proportion  of  the  component  parts  varies  in 
the  different  fpecimens  examined.  The  latter  obtained  near  one 
half  of  extra£l,  whereas  the  former  only  one  fixth. 

Scammony  is  ufed  in  medicine  as  a  purgative,  in  the  dofe  of 
feveral  grains.  When  triturated  with  fugar  and  almonds,  it 
forms  a  very  agreeable  purgative  emulfion.  When  foftened  by 
a  mixture  of  the  juice  of  liquorice,  or  of  wild  quinces,  it  forms 
the  diagredium. 

3.  Gum  guttae  has  a  reddifh  yellow  colour  :  it  has  no  fmell, 
but  its  tafte  is  acrid  and  cauftick.  Gum  guttje  was  brought  to 
Clufms  in  1630.  It  comes  from  the  kingdom  of  Siam,  from 
China,  and  from  the  ifland  of  Ceyion,  in  cylinders  of  variouij 
fizes.  The  tree  which  affords  it  is  called  Coddam  Pulli.  Her- 
man reports,  from  his  own  obfervation  as  an  eye  witnefs,  that  a 
milky  and  yellowifh  juice  flows  from  incifions  made  in  thefe 
trees ;  that  this  juice  becomes  thick  by  the  heat  of  the  fun  ;  and 
that,  when  it  is  in  a  ftate  fit  to  be  handled,  it  is  formed  into 
large  globular  mafies. 

Geoffroy  has  extracted  five  fixths  of  refin  from  gum  guttjc* 
Cartheufer  has  afcribed  to  it  more  extradive  than  refmous  mat- 
ter. 

Gum  gutt3e  is  fometimes  ufed  as  a  purgative,  in  a  dofe  of  a 
few  grains.  But  the  principal  ufe  of  this  fubRiance  is  in  paint- 
ing, where  it  is  recommended  by  the  beauty  of  its  colour. 

4.  Afla  fcetida  is  met  with  in  tears  of  a  yellowiih  white  col- 
our ;  but  moft  commonly  in  the  form  of  loaves  formed  by  the 
aggregation  of  a  number  of  the  tears.  It  has  an  acrid  and  bit- 
ter tafte,    and  its  fmell  is  one  of  the  moft  difagreeablc. 

The  plant  which  it  affords  is  called  Ferula  Affa  Foetida. 

This  plant  grows  in  Perfia  :  and  the  juice  of  its  root  is  ob- 
tained by  expreflion,  according  to  Kaempfer.  It  is  fluid  and 
white  when  it  iflues  from  the  plant,  and  it  emits  an  abominable 


M/qfiick  CuVf*  44^ 

fmtll  when  recent.  This  juice  lofes  its  fmell,  and  becomes  co/-» 
oured,  as  it  dries.  But  it  liill  preferves  fmell  enough  to  entitle 
u  to  the  name  of  Stercus  Diaboli. 

The  Indians  find  its  flavour  agreesible  ;  they  ufe  it  for  feafon^ 
Jng,  and  call  it  the  food  of  the  gods  :  a  proof  which  evinces^  bo*- 
yonii  every  argument,  that  taftes  muft  not  be  difputed. 

Cartheufer  found  it  to  contain  one  third  of  refin. 

It  is  a  folvent  and  difcutient  remedy  ;  and  more  particularly 
valuable  as  a  mofl:  powerful  antihyflerick. 

5.  Aloes  is  a  juice  of  a  red  brown  colour,  and  very  confider- 
able  bitternefs.  Three  fpecies  are  diftinguiflied — the  foccotrine 
aloes,  the  hepatick  aloes,  and  the  coballine  aloes  ;  they  differ 
only  in  their  degree  of  purity.  M.  de  Juflieu,  who  faw  thefe 
three  varieties  prepared  at  Morviedro  in  Spain,  affures  us  that 
they  are  all  obtained  from  the  aloe  vulgaris.  The  iirfl  va- 
riety is  obtained  by  making  incifions  in  the  leaves.  Time 
is  allowed  for  its  impurities  to  fubfide  perfedlly.  The  fluid  is 
then  decanted  from  the  dregs,  and  left  to  become  thick  :  after 
which  it  is  put  into  leathern  facks  for  fale,  under  the  name  o^ 
Soccotrine  aloes.  A  juice  of  the  fame  n?ture  is  obtained  by 
cxpreflTion  from  the  fame  leaves,  which,  when  clarified  in  the 
fame  manner,  forms  the  hepatick  aloes  :  and  the  coballine  aloes 
is  obtained  by  a  ftronger  preflure. 

The  Soccotrine  aloes  contains  no  more  than  one  eighth  of 
refin,  according  to  Boulduck.  The  hepatick  aloes  contains  half 
its  weight. 

Aloes  is  very  much  ufed  In  medicine  as  a  purgative,  tonick^ 
alterative,  and  vermifuge. 

6.  Gum  ammoniack  is  fometlmes  met  with  in  fmall  tears, 
white  within,  and  yellow  without.  But  they  are  often  united 
in  the  mafs,  refembling  the  benzoe  amygdaloldes. 

Its  fmell  is  fetid  ;  and  its  tafte  acrid,  bitter,  and  rather  nauleous. 

This  juice  comes  from  the  defarts  of  Africa,  and  the  plant 
which  affords  it  is  unknown  :  It  is  prefumed  to  be  of  the  clafs 
of  umbelliferous  plants,  from  the  figure  of  the  feeds  found  in  it. 

Gum  ammoniack  is  very  much  uied  In  medicine.  It  is  a  very 
good  alterative  5  and  is  given  in  pills,  incorporated  with  fugar, 
or  in  fome  extradl.  It  may  even  be  diffolved  or  diffufed  in  wa- 
ter ;  this  liquid  becomes  turbid,  and  of  a  yellowifh  white.  Gum 
ammoniack  enters  into  the  compofition  of  all  difcuffive  plafters. 

Concerning  Caoutchoack,  or  Elafl:ick  Gum. 

Elafllck  Gum  is  one  of  thofe  fubflances   which  it  Is  difficult 
it)  clafs.     It  burns  like  refins ;  but  its  foftncfs,  its  elafticity,  and 
its  infolubllity  in  the  menftruums  which  ufually  diffolve   refins, 
do  not  allow  us  to  clafs  it  among  thofe  bodies. 
2., J 


^jtr  Elajlich  Gum, 

The  tree  which  affords  It  is  known  by  the  name  of  Seringa 
by  the  Indians  of  Para.  The  inhabitants  of  the  province  of  Ef- 
meraldas,  a  province  of  Qu^ito,  call  it  Hhava  j  and  thofe  of  the 
province  of  Mainas,  Caoutchouck. 

Mr.  Richard  has  proved  that  this  tree  is  of'  the  family  of  the 
euphorbia  ;  and  Mr.  Dorthes  has  obferved,  that  the  coccus  which 
are  covered  with  a  down  that  refembles  fmall  ftraws,  were  cov- 
ered with  a  gum  very  much  refembling  the  elaftick  gum.  Thefe 
infedls  feed  on  the  euphorbium ;  but  thofe  which  come  from 
other  fituations  afford  the  fame  juice. 

We  are  indebted  to  Mr.  Condamine  for  an  account,  and  ac- 
curate details,  concerning  this  tree.  ( Acad,  des  Sciences  1 7 5 1  • ) 
This  academician  informs  us,  after  M.  Frefnau,  engineer  at 
Cayenne,  that  the  caoutchouck  Is  a  very  lofty  tree.  Incifions  are 
made  in  the  bark  •,  and  the  white  juice,  which  flows  out  in  a 
more  or  lefs  liquid  ftate,  is  received  in  a  vefTel  placed  for  that 
purpofe.  This  is  applied  in  fucceffive  coatings  upon  a  mould  of 
clay,  and  dried  by  the  fire,  or  in  the  fun.  All  forts  of  defigns 
are  traced  upon  it  while  foft  •,  and,  when  it  is  dry,  the  clay 
mould  is  cruflied,  and  the  pieces  fhaken  out. 

This  gum  is  very  elaftick,  and  capable  of  great  extenfion. 

When  elaftick  gum  is  expofed  to  the  fire,  it  becomes  foft, 
fwells  up,  and  burns  witH  a  vi^hlte  flame.  .  It  is  ufed  for  illumi- 
nation inftead  of  candles  at  Cayenne. 

It  is  not  at  all  foluble  either  in  water  or  alcohol.  But  Mac- 
quer  has  affured  us  that  ether  is  its  true  folvent ;  and  upon  this 
property  he  has  inftituted  the  art  of  making  bougies  for  chlrur- 
glcal  ufes  of  elaftick  gum,  by  applying  this  folution  upon  a 
mould  of  wax  till  it  is  of  the  requifite  thicknefs. 

Mr.  Bernaird,  to  whom  we  are  indebted  for  important  obfer- 
vations  upon  this  fubftance,  found  only  the  nitrick  ether  to  dif- 
folve  elaftick  gum.  Very  pure  fulphurick  ether  did  not  per- 
ceptibly aft  upon  it. 

If  elaftick  gum  be  put  in  contaft:  with  a  volatile  oil,  fuch  as 
that  of  turpentine,  or  even  if  it  be  expofed  to  the  vapour  of  that 
fluid,  it  fwells,  foftens,  and  becomes  very  pafty.  It  may  then 
be  fpread  upon  paper,  or  applied  as  a  varnifti  to  cloth  •,  but  this 
covering  preferves  its  adhefive  quality,  and  does  not  lofe  it  for  a 
long  time.  The  mixture  of  volatile  oil  and  alcohol  forms  2 
better  folvent  than  the  pure  oil,  and  the  varnifh  dries  more 
fpeedily. 

Mr.  Bernaird  has  concluded  from  his  experiments  that  the 

elaftick  gum  is  a  fat  oil,  coloured  by  a  matter  foluble  in  alcohol, 

and  foiled  by  the  fmoke  to  which  the  gum  is  expofed  in  drying. 

If  linfeed  oil  be  rendered  very  drying  by  digefting  it  upon  the 

oxides  of  lead,  and  it  be  afterwards  applied  with  a  fmall  brufli 


VaYnijh  of  the  Chinejc»  ji^p^^ 

upon  any  furface,  and  dried  by  the  fun  or  in  the  fmoke,  it  af- 
fords a  pellicle  of  a  confiderable  degree  of  firmnefs,  evidently 
tranfparent,  burning  like  the  elaftick  gum,  and  wonderfully 
elaftick  and  extenfible.  If  this  very  drying  oil  be  left  in  a  wide 
{hallow  veflel,  the  furface  becomes  thick,  and  forms  a  membrane 
which  has  the  greateft  analogy  with  the  elaftick  gum.  A  pound 
of  this  oil  fpread  upon  a  ftone,  and  expofed  to  the  air  for  fix  or 
feven  months,  acquired  almoft  all  the  properties  of  elaftick 
gum.  It  was  ufed  to  make  catheters  and  bougies ;  was  applied 
to  varnifti  balloons,  &c. 

Some  gum  rcfins  are  cleared  by  art  of  their  extra<flivc  princi- 
ple for  the  purpofe  of  applying  them  to  various  ufes.  Such  is 
the  intention  of  the  procefs  ufed  to  make  bird-lime.  This  is 
made  from  different  fubftances,  as  the  berries  of  mifletoe,  the 
fruit  of  the  febeften,  &c.  Bur  the  beft  is  made  of  the  hoUyoak. 
Thefe  trees  are  peeled  in  the  month  of  June  or  July  :  the  outer 
bark  is  rejected,  and  the  fecond  is  boiled  in  fpring  water  for 
feven  or  eight  hours.  It  is  then  made  into  molaffes,  which  are 
buried  in  the  ground,  and  covered  with  ftones,  for  feveral  layers 
one  over  the  other.  After  having  previoully  drained  off  the 
moifture,  they  are  fuffered  to  ferment  for  fifteen  days,  until  the 
matter  has  acquired  the  adhefive  confiftence  of  pafte.  The 
mafs  is  then  beaten  till  it  becomes  capable  of  being  wrought 
with  the  hands,  or  kneaded ;  after  which  it  is  waftied  in  a  run- 
ning ftream.  Laftly,  it  is  placed  for  three  or  four  days  in 
another  veffel,  that  it  may  throw  up  its  fkum  or  impurities  ;  in 
which  laft  ftate  it  is  put  into  proper  veffels,  and  kept  for  ufe. 

The  following  compofition  is  likewife  made  ufe  of  under  the 
name  of  bird-lime.  Take  one  pound  of  bird-lime,  one  pound 
of  goofe-greafe  ;  add  to  this  one  ounce  of  vinegar,  half  an  ounce 
of  oil,  and  the  fame  quantity  of  turpentine.  Boil  the  mixture 
for  feveral  minutes,  and  heat  the  mafs  when  you  are  defirous  of 
ufing  it  as  a  cement..  It  may  be  prevented  from  freezing  in 
winter,  by  adding  a  fmall  quantity  of  petroleum. 

Concerning  Varnifli. 

The  Pere  d'Incarville  has  informed  us  that  the  tree  which  af- 
fords the  Varnifli  of  China  is  called  Pfi-chou  by  the  Chinefe. 
This  tree  is  propagated  by  off-fets.  When  the  cultivator  is  de- 
firous of  planting  this,  he  takes  a  branch,  which  he  wraps  up  in 
a  mafs  of  earth,  by  means  of  flax.  Care  is  taken  to  moiften 
this  earth  ;  the  branch  puflies  out  roots,  and  is  then  pruned  and 
tranfplanted.     This  tree  grows  to   the  fize  of  a  man's  leg. 


45*  ^^i  of  Tarnijiiing, 

This  varnuTi  is  drawn  in  fpring.  If  it  be  a  cultivated  tree, 
it  affords  three  gatherings.  It  is  extracted  by  incifions  made  in 
the  fpring  ;  and  when  the  varnifh  which  is  received  in  (hells  does 
not  flew,  feverai  hog's  briftles,  moiftened  with  water  or  fpittle 
are  introduced  into  the  wound,  and  caufe  it  to  run.  When  the 
tree  is  exhaufted,  the  upper  part  of  it  is  wrapped  in  ftraw,  which 
is  fet  on  fire,  and  caufes  the  varnifti  to  precipitate  to  the  bottom 
of  the  tree,  where  it  flows  out  of  perforations  made  for  that 
purpofe. 

Thofe  who  coll^ft  the  varnifh  fet  out  before  day-break,  and 
place  their  fliells  beneath  the  apertures.  The  fliells  are  not  left; 
longer  than  three  hours  in  their  place,  becaufe  the  heat  of  the 
Ain  would  evaporate  the  varnilh. 

The  varni(h  emits  a  fmell  which  the  workmen  are  very  care-* 
ful  to  avoid  refpiring.  It  produces  an  efFe£l  which  they  call  the 
bud  of  the  varnifli. 

When  the  varnifh  iflues  from  the  tree,  it  refembles  pitch. 
By  expofure  to  the  air  it  naturally  becomes  coloured,  and  is  at 
Jail  of  a  beautiful  black. 

The  juice  which  flows  from  incifions  made  in  the  trunk  and 
branches  of  the  thus  toxicodendron,  pofTefTes  the  fame  proper^ 
ties.  The  tree  that  grows  in  our  climates  affords  a  while  mil- 
ky fluid,  which  becomes  black  and  thick  by  the  conta<?fc 
of  the  air  ;  its  colour  is  the  moft  beautiful  black  :  and 
it  would  be  eafy  to  introduce  this  valuable  fpecies  of  induftry 
into  the  kingdom,  becaufe  the  tree  grows  wonderfully  well  in 
all  climates,  and  refifts  the  cold  of  the  winter. 

To  make  the  Varnifh  bright,  it  is  evaporated  by  the  fun  ;  and 
a  body  is  given  to  it  with  hog's  gall,  and  the  fulphate  of  iron,  or 
martial  vitriol. 

The  Chinefe  ufe  the  oil  of  tea,  which  they  render  drying  by 
boiling  it  with  orpiment,  v  realgar,   and  arfenick. 

The  varnifhcs  moft  ufed  in  the  arts  have  all  of  them  the  refins- 
for  their  bafe  ;  and  the  fundamental  facts  in  this  valuable  art 
are  reducible  to  the  following  principles. 

To  varnilli  any  fubftance,  confiOis  in  applying  upon  its  fur- 
face  a  covering  of  fuch  a  nature,  as  fliail  defend  it  from  the  in- 
fluence of  the  air,  and  give  it  a  fliining  appearance. 

A  coat  of  varniili  ought  therefore  to  poffefs  the  following 
properties  : — i.  It  muft  exclude  the  adlion  of  air  ;  becaufe  wood 
and  metals  are  varnifhed  to  defend  them  from  decay  and  raft  * 
-2.  It  muft  refill:  vi^ater  ;  forotherwife  the  effe£l  of  the  varnifli 
could  not  be  permanent,  3.  ft  ought  not  to  alter  fuch  coioure 
;jt$  are  intended  to  be  preferved  by  this  mqan%     * 


Arf  of  Tarnijh'ing,     Fectiia,  4^5 

It  is  necei!ary  therefore  that  a  varnifli  (hould  be  eafily  extend- 
ed or  fpread  over  the  furface,  without  leaving  pores  or  cavities ; 
that  it  {liouid  not  crack  or  fcaie  ;  and  that  it  Ihould  refift  vi^ater. 
Nou'  refins  are  the  only  bodies  that  pofTefs  thefe  properties. 

Refins  coniequently  muft  be  ufed  as  the  bafes  of  varnifh. 
The  queftion  which  of  courfe  prefents  itfelf  muft  then  be,  how 
to  dilpofe  them  for  this  ufe  -,  and  for  this  purpofe  they  muft  be 
diflblved,  as  minutely  divided  as  poflible,  and  combined  in  fuch 
a  manner  that  the  imperfedlions  of  thofe  which  might  be  dilpo- 
fed  to  fcale,  may  be  corretted  by  others. 

Refins  may  be  diftblved  by  three  agents — i.  By  fixed  oil.  2. 
By  volatile  oil.  3.  By  alcohol.  And,  accordingly,  we  have 
three  kinds  of  varniih,  the  fat  or  oily  varnilh,  eflential  varnifli, 
and  fpirit  varnifli.  s 

Before  a  refin  Is  diflblved  in  fixed  oil,  it  is  necefl^ary  to  render 
the  oil  drying.  For  this  purpofe  the  oil  is  boiled  with  metallick 
oxides  ;  in  which  operation  the  mucilage  of  the  oil  combines 
with  the  metal,  while  the  oil  itfelf  unites  with  the  oxigene  of  the 
oxide.  To  accelerate  the  drying  of  this  varnifli,  it  is  necellary 
to  add  oil  of  turpentine. 

The  efl^ential  varnifhes  confift  of  a  folutlon  of  refin  in  oil  of 
turpentine.  The  varnifli  being  applied,  the  efl^ential  oil  flies  ofl^, 
and  leaves  the  refin.     This  is  ufed  only  for  paintings. 

When  refins  are  diflblved  in  alcohol,  the  varnifli  dries  very 
fpeedily,  and  is  fubje6l  to  crack  ;  but  this  fault  is  corre£l:ed  by- 
adding  a  fmall  quantity  of  turpentine  to  the  mixture,  which  ren- 
ders  it  brighter,  and  lefs  brittle  when  dry. 

The  coloured  refins  or  gums,  fuch  as  gum  guttx,  dragon'$ 
blood,  &c.  are  ufed  to  colour  varniflies. 

To  give  luftre  to  the  varnifli  after  it  is  laid  on,  it  is  rubbed 
with  pounded  pumice  ftone  and  water  ;  which  being  dried  with 
a  cloth,  the  work  is  afterwards  rubbed  with  an  oiled  rag  and 
tripoli.  The  furface  is  laft  of  all  cleaned  with  foft  linen  cloths, 
cleared  of  all  greafinefs  with  powder  of  ftarch,  and  rubbed 
bright  with  the  palm  of  the  hand. 


ARTICLE     VI. 

Concerning  the  Fecula  of  Vegetables. 

The  fecula  appears  to  be  only  a  flight  alteration  of  mucilage ; 
for  it  difitirs  from  that  fubftance  in  no  other  refpe£l  than  in  be- 
ing infoluble  in  cold  water,  in  which  liquid  it  falls  with  wonder- 
ful quvgknefs.     \i  it  be  put  into  hot  water^  it  forms  4  mucilage^ 


454  Various  kinds  of  Fecula, 

and  refumes  all  its  charaders.  It  feems  that  the  fecula  is  fim- 
ply  a  mucilage  deprived  of  calorick.  In  fa6l  a  young  plant  is 
all  mucilage  •,  the  old  plants  and  fruits  afford  little  fecula,  be- 
caufe  the  heat  is  ftronger  in  young  than  in  old  plants,  according 
to  Dr.  Hunter. 

There  are  few  plants  which  do  not  contain  fecula.  Mr. 
Parmentier  has  given  us  a  lift  of  all  thofe  which  afford  it,  in 
his  experiments.  (See  his  Recherches  fur  les  Vegeteaux  Nourif- 
ians.)  But  the  feeds  of  gramineous  and  leguminous  vegetables, 
as  well  as  the  roots,  which  botanifts  call  Tuberofe,  contain  it 
moft  plentifully. 

Nothing  more  is  required,  in  order  to  extra<fl:  the  fecula,  than 
to  bruife  or  grind  the  plant  in  water  -,  and  the  fecula  which  is 
^t  firft  fufpended  in  that  fluid,  foon  falls  to  the  bottom.  We 
fiiall  not  in  this  place  attend  to  any  other  fecula  bift  fuch  as  are 
ufed  in  the  arts  or  in  medicine.  Such  are  thofe  of  bryony,  of 
potatoes,  caffava,  fago,  falep,  ft  arch,  &c. 

1.  The  fecula  of  bryony  is  extracted  from  the  root  of  that 
plant.  The  bark  is  firft  taken  off  from  the  root,  which  is  then 
rafpcd,  and  fubmitted  to  the  prefs.  The  juice  which  flows  out 
by  expreilion  is  rendered  white  and  opaque  by  a  fecula  which 
fubfides.  The  liquid  is  then  decanted  off,  and  the  fecula  dried. 
It  is  ftrongly  purgative,  on  account  of  a  portion  of  extradt 
which  it  retains  j  but  it  may  be  deprived  of  its  purgative  virtue 
by  careful  wafhing  in  water.  If  water  be  poured  on  the  marc 
which  remains  beneath  the  prefs,  a  large  quantity  is  obtained 
which  is  not  purgative,  becaufe  the  extractive  matter  was  forced 
out  by  the  firft  operation.  Mr.  Baume  has  propofed  to  fubfti- 
tute  this  fecula  inftead  of  ftarch.  The  fecula  is  afforded  by 
fimilar  treatment  of  the  roots  of  corn-flag  and  arum. 

2.  That  which  is  generally  known  by  the  name  of  potatoe 
flour,  is  nothing  but  the  fecula  of  this  root  obtained  by  ordinary 
and  eafy  proceffes.  '  The  root  being  well  wafhed,  it  is  pounded 
or  cruflied  in  fuch  a  manner  as  perfedlly  to  deftroy  its  texture. 
The  pulp  is  then  put  into  a  fieve,  and  water  poured  on  it,  which 
carries  off  the  fecula,  and  depofites  it  at  the  bottom  of  the  re- 
ceiving veffel.  The  water,  which  is  coloured  by  extractive  mat- 
ter, and  part  of  the  parenchyma  that  remains  fufpended,  is  de- 
canted eff,  and  the  depofition  is  waflied  feveral  times.  The 
colour  of  the  fecula  grows  whiter  as  it  dries  ;  and  when  dry  it 
is  very  white  and  fine. 

As  this  fecula  has  become  an  article  of  common  ufe  for  fome 
time  paft,  feveral  inftruments  have  been  contrived  which  are 
more  or  lefs  fuited  to  bruife  the  potatoes.  Rafps  have  been 
popofed  turning  in  cylinders,  mills  armed  with  points  of  iron, 
&c. 


Various  hinds  cf  Fecula,  4,^  J 

3.  The  caflava  of  the  Americans  is  extracted  from  the  roots 
of  the  maniock.  This  plant  contains  an  acrid  and  very  danger- 
ous poifon,  of  which  it  muft  be  very  carefully  deprived.  The 
Americans  take  the  frefli  root  of  maniock,  which  they  peel,  rafp, 
and  inclofe  in  a  bag  or  fack  formed  of  ruflies,  and  of  a  very  open 
texture.  This  bag  is  fufpended  from  a  ftafF;  and  a  very  heavy 
veffel  is  faflened  to  its  lower  part,  which  draws  the  bag  down, 
fo  as  in  fome  meafure  to  comprefs  the  root,  at  the  fame 
time  that  it  receives  the  juice  as  it  flows  out.  The  juice  is  a 
mod  dreadful  poifon.  When  the  root  is  well  cleared  of  the 
juice,  it  is  put  into  the  fame  bags,  and  expofed  jto  dry  in  the 
fmoke.  The  fifted  root  is  called  Caflava.  To  convert  it  into 
food,  it  is  fpread  out  on  a  hot  brick,  or  plate  of  iron  ;  and 
when  the  furface  which  refls  immediately  on  the  brick  is  of  a 
reddifh  brown  colour,  it  is  turned,  to  bake  the  other  fide  ;  and 
in  this  flate  it  forms  what  is  called  Cafllwa  bread. 

The  ex:  refled  juice  carries  with  it  the  fincft  part  of  the  fecula 
which  quickly  fubfides  ;  and  this  fecula,  known  by  the  name  of 
MoiichaflTe,  is  ufed  to  make  paltry. 

The  poifonous  extract  which  mod  of  thefe  roots  that  abound 
in  fecula  contain,  ought  to  engage  thofe  who  prepare  them  to  be 
uncommonly  attentive  to  the  due  management  of  the  procefs. 
Without  the  mofl  fcrupulous  care  the  mo(t  unhappy  confequen- 
ces  may  follow.  It  fhould  always  be  recollected,  in  the  prepar- 
ation of  thefe  fubftances,  that  the  poifon  is  in  contact  with  the 
food. 

4.  A  fecula  has  likewife  been  appropriated  to  domeftick  ufes 
which  is  extracted  from  the  pith  of  feveral  farinaceous  palms, 
and  is  known  by  the  name  of  Sago.  This  preparation  is  made 
in  the  Molucca  Iflands.  The  pith  of  middle  aged  palms  is  only 
ufed  ;  for  the  young,  as  well  as  the  old,  aflx>rd  very  little  fecu- 
la. This  pith  is  mixed  with  water  •,  and  the  fecula  which  is 
extradled,  and  renders  the  fluid  white,  is  fufFered  to  fubfide. 
When  the  fecula  is  dried,  it  forms  fmall  grains  ;  which,  when 
reduced  to  powder,  and  mixed  with  warm  water,  affords  a  very 
nourifhing  pulp  or  mucilage. 

M.  Parmentier  has  propofed  to  make  fago  out  of  potatoes  ; 
in  confequence  of  his  idea  that  all  feculx  are  abfolutely  identi- 
cal, and  that  this  principle  is  one  and  the  fame  in  nature.  For 
this  purpofe  he  propofes  to  add  a  fpoonful  of  the  fecula  of  pota- 
toes gradually  to  a  chopin,  or  half  a  pint,  of  hot  water  or  milk, 
to  be  kept  (tirring  over  a  gentle  fire  for  half  an  hour.  Sugar 
may  be  added,  with  aromaticks  or  fpices,  fuch  as  cinnamon,  lem- 
on peel,  faflVon,  orange  flower  water,  rofe- water,  &c. 


4$4  XJfes  of  Fecula, 

V 

The  fago  of  potatoes  may  likewife  be  prepared  with  ve-af 
broth,  chicken  broth,  or  common  broth.  The  preparation  may 
be  varied  in  a  thoufand  ways,  and  it  forms  a  very  wholefomc 
and  nourifhing  food. 

5.  The  buibs  of  all  the  kinds  of  orchis  may  be  ufed  to  make 
falep.  All  that  is  required  to  be  done  confifts  in  depriving  them 
of  the  extractive  principle,  and  drying  the  refidue  which  be- 
comes tranfparcnt  by  this  operation. 

In  order  to  dry  them  more  fpeedily,  they  are  ftrung,  and  hung 
up  ;  or  otherwife  it  is  thought  fufficient  to  rub  thefe  bulbs  in 
water  either  hot  or  cold,  and  to  dry  them  in  an  oven.  This 
lad  procefs  was  communicated  to  Dr.  Percival  by  Mr.  John 
Moult. 

The  fecula  of  falep,  pulverized,  and  combined  with  water, 
Ibrms  a  very  no«irifhing  jelly. 

6.  The  fecula  is  likewife  one  of  the  conftituent  principles  of 
the  feeds  of  gramineous  plants  •,  and  when  thefe  have  been  ground 
and  reduced  into  farina,  nothing  more  is  required  than  to  mix: 
them  with  water,  in  order  to  precipitate  the  fecula.  But  anoth- 
er procefs  for  procuring  it  is  ufed  in  the  arts  *,  it  confifts  in  de- 
ftroying  by  fermentation  the  extractive  and  glutinous  part  with 
•which  it  is  intimately  united  5  and  in  this  confifts  the  art  of  ma- 
king ftarch.  The  procefs  of  the  iliarch-maker  confifts  in  fer- 
menting grain,  pollard,  damaged  flour,  &c.  in  the  acid  water 
which  they  call  eaufure.  When  the  fermentation  is  ended,  they 
take  out  the  fecula,  which  is  precipitated  to  the  bottom  of  ths 
water,  and  put  it  into  hair  facks.  Frefh  water  is  poured  upon 
this,  which  carries  the  finer  fecula  with  it  ;  and  this  being  fev-' 
cral  times  wafhed,  conftitutes  ftarch,  cleared  of  every  foreign 
principle. 

There  are  likewife  coloured  feculac,  fuch  as  indigo,  which  we 
fhall  treat  of  when  we  come  to  the  article  dying. 

The  nfes  of  feculce  are  very  numerous. 

I.  They  conftitute  a  very  nouri(hing  food,  becaufe  the  nutri- 
tive virtue  of  gramineous  vegetables  rcfides  in  them.  Thofq 
feeds  which  man  has  appropriated  for  his  food,  contain  much  ; 
and  thefe  feculx  form  a  very  nouriftiing  jelly  with  hot  water. 
It  may  be  feeii,  in  the  work  of  Mr.  Parmentier,  that  this  is  truly 
the  moft  fuitable  nourilhment  for  man.  Some  of  thefe  are  e- 
yen  entirely  devoted  to  this  purpofe,  fuch  as  the  cafTava. 

In  the  northern  climates,  the  lichens  form  almoft  the  whole 
of  the  food  of  man,  and  fuch  animals  as  are  not  carnivorous  j 
and  thefts  lichens,  according  to  the  experiments  of  the  Academy 
of  Stockholm,  afford  an  excellent  ftarch  by  fimple  grinding. 
The  rein-deer,  the  ftags,  and  the  other  fallow  cattle  of  the 
north  of  Europe,  fubftft  on  the  lichen  rangiferinus.     The  Ice- 


YegetahU  Gluten,  it^^^ 

yfiders  obtain  a  very  delicate  gruel  with  fecula  of  the  lichen  loe- 

landicus.  »      r     n  • 

1.  Starch  boiled  in  water,  and  coloured  with  a  fmall  quantity 
of  azure,  forms  a  pafte  which  is  ufed  to  give  brightnefs,  firm- 
nefs,  ftrength  and  an  agreeable  colour  to  linen. 

The  fecula;  are  alfo  ufed  to  make  hair  powder ;  and  this  con- 
fumption,  which  is  prodigious,  might  be  fupplied  by  ftarch 
made  from  lefs  valuable  plants  than  the  gramineous  ;  and,  if  this 
were  done,  the  objects  of  luxury  would  not  enter  into  competi- 
tion with  our  immediate  wants. 


i\RTICLE  VII. 

Concerning  the  Vegetable  Gluten. 

The  glutinous  principle,  which  on  account  of  its  properties 
refembling  thofe  of  animal  fubltances,  has  been  called,  the  Veg- 
cto-Animal  fubftance  by  feme  chemiits,  is  more  particulcirly  ob- 
tained from  gramineous  vegetables.  We  are  indebted  to  Bcc- 
cari  for  the  difcovery  of  this  fubftance  ;  and  the  analyfis  of  far- 
inaceous fubltances  has  fmce  been  enriched  with  various  impor- 
tant fafls. 

To  make  the  analyfis  of  any  farina,  the.  methods  employed 
are  fuch  as  are  fimple,  and  incapable  of  decompofing  or  alter- 
ing any  of  its  conftituent  parts.  A  pafte  is  formed  with  the 
flour  and  water  ;  and  this  is  kneaded  and  wrought  in  the  hands 
under  water,  till  it  no  longer  communicates  any  colour  to  that 
fluid.  The  fubftance  which  then  remains  in  the  hand  is  tena- 
cious, ductile,  and  very  elallick  -,  and  becomes  more  anil  more 
adhefive,  in  proportion  as  the  water  which  it  had  imbibed  flies 
off  by  evaporation.  In  this  fame  operation  the  fecula  falls  to 
the  bottom  of  the  water  j  while  the  extractive  matter  remains 
in  folution,  and  may  be  concentrated  by  evaporation  of  the 
fluid. 

If  the  glutinous  matter  be  ftretched  out,  and  then  let  go,  it 
returns  by  fpontancous  contraction  to  its  original  form.  If  it 
be  left  fufpended,  it  becomes  extended  by  its  weight  ;  and  forms 
a  very  thin  tranfpiircnt  membrane,  which  exhibits  a  kind  of  net- 
work, refembling  the  texture  of  the  membranes  of  animals. 

M.  Beccari  has  obfcrved  that  the  proportion  of  glutinous  mat- 
ter varies  prodigioufly  in  the  fcvcral  fcials  of  gramineous  ver^e- 
tables.  Thofe  of  wheat  contain  the  Iri^geft  quantity  ;  but  he 
never  found  it  in  the  garden  ftuft'or  plants  M'hich  arc  ufed  by 
us  for  food.  The  quantity  of  glutinous  m-itter  alfo  varies  in  the 
iame  kind  of  grain,  according  to  the  nature  of  the  foil  which 
has  fupported  it.  Humid  fu uations  ailord  icarcely  anv. 
3...K 


45^  Fegetahk.  QiuUfU 

The  glutinous  matter  emits  a  very  chara.<^eri{lick  hmmt^l  fmelL 

Its  tafte  is  inlipid  ;  it  fwells  up  upon  hot  coals  ;  becomss  foon 
and  perfectly  dry  in  a  dry  air,  or  by  a  gentle  heat  ;  in  which 
fiate  it  refembles  glue,  and  breaks  ftiort  like  that  fubftance.  If 
in  this  ftate  it  be  placed  upon  burning  coals,  it  curls  up,  is  agir 
tated,  and  burns  like  an  animal  fubftance.  By  diftillation  it  af- 
fords the  carbonate  of  ammoniack. 

Frefh-made  gluten,  expofed  to  ih^  air,  readily  putrefies  ;  and 
when  it  has  retained  a  fmall  quantity  of  (larch,  this  laft  paiTei 
to  the  acid  fermentation,  and  retards  the  putrefiicUon  of  the 
gluten  :  and  in  this  way  a  ftate  is  produced  refembling  that  of 
chcefe. 

Water  does  not  attack  the  glutinous  part.  If  it  be  boiled 
with  this  fluid,  it  lofes  its  extenfibiJity  and  adhefive  quality  ;  a 
circumftance  fo  much  the  more  remarkable,  as  it  was  indebted 
to  that  fluid  for  the  developement  of  thefe  qualities  ;  for  this 
principle  cxifted  without  cohefion  in  the  flour  ;  and  when  it  is 
deprived  of  water  by  drying,  it  alfo  lofes  its  elafticity  and  gluti- 
nous quality. 

Alkalis  diflblve  it,  by  the  afhftance  of  a  boiling  heat.  The  fo«» 
lution  is  turbid  ;  and  depofites  the  gluten  by  the  addition  o£ 
acids,  but  deprived  of  its  elafticity. 

The  nitrick  acid  diflfolves  gluten  with  a£bivity  ;  and  this  acid 
at  firft  emits  the  nitrogenous  gas,  as  when  treated  with  animal 
fubftances.  This  is  followed  by  an  emiflHon  of  nitrous  gas  ;  and 
the  relidue,  by  evaporation,  affords  the  oxalick  acid   in  cryftals. 

The  fulphurick  and  muriarick  acids  likevvife  diflblve  it.  M* 
Poulletier  has  obferved,  that  falts  with  bafe  of  ammoniaek  may  be 
obtained  from  thefe  combinations  diflblved  in  water  or  alcohol, 
and  evaporated  in  the  open  air. 

If  the  gluten  be  diflblved  in  the  vegetable  acids  feveral  times 
repeatedly,  and  precipitated  by  alkalis,  it  is  reftored  to  the  ftate 
of  fecula  :  and  according  to  Macquer,  if  vinegar  be  diftilled  by 
a  gentle  heat  from  this  fubftance,  it  is  reduced  to  the  ftate  of 
mucilage. 

This  fubftance  therefore  poflefles  a  very  decided  animal  char- 
acter. It  is  to  this  gluten  that  wheat  owes  its  property  of  mak- 
ing a  good  pafte  with  water,  and  the  facility  with  which  it  rifes, 
Rouelle  difcovered  a  glutinous  fubftance  analagous  to  the  pref- 
ent  In  the  green  fecula  of  plants,  which  afibrded  ammoniaek, 
and  empyreumatick  oil,  by  diftillation.  The  exprcfled  juice  of 
the  herbaceous  plants  likewife  aflbrded  it  *,  fuch  as  that  of  bo- 
rage, hemlock,  fbrrel,  &c. 

The  Gluten  is  fometimes  dcftroyed  by  the  fermentation  of 
flour  J  by  which  change  it  is  deprived  of  the  wholefome  quali- 


Ferttiefiicii'ton  of  B/ead,     Sugat\  ^^m 

trcs  It  before  pofTeflctS,  and  is  incapable  of '  ri£ng,  and  forming 
^ood  bread. 

Ferina,  or  flour,  is  therefore  compofed  of  three  principles — * 
the  amylaceous  principle^  or  flarch  ;  the  faccharine  principle  i 
and  the  animal  or  glutinous  principle.  Whenever  therefore, 
by  a  fuitable  divifion,  thefe  principles  are  mixed  together,  and 
the  fermentatioh  is  afTilted  by  the  known  methods,  each  of 
thefe  principles  being  capable  of  a  different  kind  of  fermentation, 
becomes  depofed  in  its  own  peculiar  manner.  The  faccharine 
principle  undergoes  the  fpirituous  fermentation  :  and  the  amyl- 
aceous is  changed  by  the  acid  fermentation.  The  panary  fer- 
mentation may  therefore  be  confidered  as  an  union  of  thefe  three 
tiiflPerent  fpontaiiebus  changes.  But  as  foon  as  the  leading  phe- 
nomena of  the  fermentation  are  well  developed  ;  and  the  prin- 
ciples, already  well  mixed  and  aflimilated,  have  by  this  means 
j^iffered  a  change  of  their  rcfpe<Stive  natures  ;  the  fermentation 
is  ftopped  by  baking  :  and  the  bread  is  found  to  be  much  lighter 
in  confequence  of  thefe  preliminary  operations. 

The  ^Tt  of  making  bread  was  not  known  at  Rome  iintil  the 
year  5  85.  The  Roman  armies,  on  their  return  from  Macedo- 
nia ;  brought  Grecian  bakers  into  Italy.  Before  this  time  the 
Romans  prepared  their  flour  in  no  other  way  than  by  making 
it  into  pap  or  foft  pudding  j  for  which  reafon  the  Romans,  ac- 
feordirtg  to  Pliny^  Were  called  eaters  of  Pap.*     See  Aubery. 


ARTICLE    VIIL 

Concerning  Sugar. 

Sugar  IS  likewife  a  conftituent  part  of  vegetables,  exifling  in 
confiderabie  quantities  in  a  number  of  plants.  It  is  aflbrded  by 
the  maplei  the  birch,  wheat  and  turkey  corn.  P^argrafF  ob- 
tained it  from  the  roots  of  beet,  red  beet,  Ikirret,  parfnips,  and 
dried  grapes.  The  procefs  of  this  chemlfl  confilted  in  digefting 
thefe  roots,  rafpcd  or  finely  divided,  in  alcohol.  This  fluid  dif- 
folves  the  fugar  j  and  leaves  the  extraflive  matter  untouched, 
which  falls  to  the  bottom. 

In  Canada  the  inhabitants  extradl  fugar  from  the  maple  (acer 
montanumxandidum.)  At  the  commencement  of  fpring  they 
heap  fnow  in  the  evening  at  the  i"oot  of  the  tree,  in  which  they 
previoufly  make  apertures  for  the  pafl^age  of  the  returning  fap, 

•  *  Pulte  autem  non  pane,  vixIiTe  longo  terfipore  Romanos  manifefturti 
<iuqnlum  inde  et  Pulmentaria  hodiequc  dicqntur.  Piin.  Hift.  Nat.  ibj 
^fiii.  cap.  viii,  ct  xi.— The  date  is  580  ab  mbe  condica.    T. 


-'4^9  Beetling  and  Refining  of  Sugar, 

Two  hundred  pound's  of  this  juice  afford  Ky  evaporation  fifteen 
of  a  brovvnifti  fagar.  The  quantity  prepared  annually  amount* 
to  fifteen  thoufand  weight. 

The  Indians  fikewife  extract  fugar  from  the  pith  of  the 
bamboo. 

But  the  fugar  which  is  fo  univerfally  ufed  is  afforded  by  the 
fugar  cane  (arunda  faccharifera)  which  is  raifed  in  our  colonies. 
When  tliis  plant  is  ripe,  it  is  cut  down,  and  cruflied  by  paiTmg 
it  between  iron  cylinders,  placed  perpendicularly,  and  moved 
by  M^ater  or  animal  Itrength.  The  juice  which  flows  out  by 
this  ftrong  prefTure  is  received  in  a  fliallow  trough  placed  bcf 
neath  the  cylinder.  This  juice  is  called  vefoii  ;  and  the  cane, 
after  having  undergone  this  preflure,  is  called  hegaffe.*  The 
juice  is  more  or  lefs  faccharine,  according  to  the  nature  of  the 
foil  on  which  the  cane  has  grown,  and  the  weather  that  has  pre- 
dominated during  its  growth.  It  is  aqueous  when  the  foil  or 
the  weather  has  been  humid  ;  and  in  contrary  circumflances  it 
is  thick  and  glutinous. 

The  juice  of  the  cane  is  conveyed  into  boilers,  where  it  is 
boiled  with  wood  allies  and  lime.  It  is  fubje£led  to  the  fame 
operation  in  three  feveral  boilers,  care  being  taken  to  remove 
the  fkum  as  it  rifes.  In  this  fl.ate  it  is  called  Syrup  ;  and  is  a- 
gain  boiled  with  lime  and  alum  till  it  is  fufficiently  concentrated, 
when  it  is  poured  into  a  veflel  called  the  Cooler.  In  this  veflel 
it  is  agitated  wkh  wooden  flirrers,  which  break  the  cruil  as  it 
forms  on  tht^furface.  It  is  aft;:rwards  poured  into  caflcs,  to  ac-^ 
celerate  its  cooling  ;  and,  while  it  is  ftill  warm,  it  is  conveyed 
into  barrels  ftanding  upright  over  a  ciflern,  and  pierced  through 
their  bottom  with  feveral  holes  flopped  vrith  cane.  The  fyrup 
which  is  not  condenfcd  filters  through  thefe  canes  into  the  cif- 
tern  beneath;  and  leaves  the  fugar  in  the  flate  called  Coarfc 
Sugar,  or  Mufcovado.  This  fugar  is  yellow  and  fat,  and  is  pu- 
rified in  the  iilands  in  the  following  manner  :— The  fyrup  is 
boiled,  and  poured  into  conical  earthen  vefiels,  having  a  fmall 
perforation  at  the  apex,  which  is  kept  clofed.  Each  cone,^  re- 
verfed  on  irs  apex,  is  fupported  in  another  earthen  veffel.  The 
fyrup  is  flirred  together, '  and  then  left  to  cryiiiMze.  At  the 
end  of  fifteen  or  fixteen  hours,  the  hole  in  the  point  of  each 
cone  is  opened,  that  the  impure  fyrup  may  run  out.  The  bafe 
of  thefe  fugar  loaves  is  then  taken  out,  and  white  pulverized  fu- 
gar fubftituted*in  its  ftead  ;  which  being  well  prefTed  down,  the 
whole  is  covered  with  clay,  moiftened  with  water.  This  water 
fihers  through  the  mafs,  carrying  the  fyrup  with  it  which  wa? 

*  Thefe  ar?  the  nc^mes  in  the  French  fugar  .colonies.  I  do  not  End  th? 
corresponding  tei.T.s  in  any  of  our  writers,     f-  ' 


Habitudes  of  Sugme7'  •  "**  461 

inixed  with  thc^fugar,  but  which  by  this  management  flows  in- 
to a  pot  fubftituted  in  the  place  of  the  firft.     This  fecond  fluid 
is  called  Fine  Syrup.      Care  is  taken  to  moiften  and  keep    the 
clay  to  a  proper  degree  of  foftnefs,  as  it  becomes  dry.      The 
lugar  loaves  are  afterwards  taken  out,   and  dried  in  a   ftove 
for  eight  or  ten  days ;  after  which  they  are  pulveiized,   packed 
j^and  exported  to  Europe,   where   they  arc   ftiil  farther  puri- 
ied. 
TLe  operation  of  our  fugar  refiners  confifts  in  diflblving  caf- 
\fonade,  or  clayed  fugar,  in  lime-water.     Bullock's  blood  is  ad- 
led,  to  promote  the  clarifying  ;    and  when  the  liquor  begins  to 
boil,   the.  heat  is  diminifhed,   and  the  fkum  carefully  taken  off. 
flit  is  in  the  next  place  concentrated  by  a  briik  heat ;    and,  as  it 
:  boils  up,  a  fmall  quantity  of  butter  is  thrown  in,  to  moderate  its 
■agitation.     When  the  boiling  is  fuHiciently   effected,  the  fire  is 
put  out ;  the  liquor  is  poured  into  moulds,  and  agitated,  to  mix 
>.tlie  fyrup  together  with  the  grain  fugar  already  formed.    When 
^^the  whole  is  cold,  the  moulds  are  opened,  the  loaves  are  covered 
-with  moiltened  clay,  which  is  renewed  from  time  to  time  till 
'the  fugar  is  well  cleared  from  its  fyrup.     The  loaves  being  then 
itaken  out  of  the  moulds,  are  carried  to  a  ftove,  where  they  are 
^gradually  heated  to  the  fiftieth  degree  of  Reaumur.      They  re- 
»-«iain  in  this  ftove  eight  days,  after  which  they  are  wrapped  in 
blue  paper  for  fale. 

.     The  feveral  fyrups,  treated  by  the  fame  methods,  afford  fu- 

gars  of  inferiour  qualities  ;  and  the  laft  portion,  which  no  long- 

t-jer  affords  any  cryftals,   is  fold  by'the  name  of  Melaffes.      ^Tlie 

Spaniards   ufe   this   melaffes    in   the   preparation  of    fwcet- 

r;^eats. 

-     A  folution  of  fugar,  much  lefs  concentrated  than  that  we  have 
'ijuft  been  fpeakingof,  lets  fall  by  repofe,cryilals  which  affe6l  the 
^fprm  of  tetrahedral  prifms,  terminated  by  dihedral  fummits,  and 
'known  by  the  name  of  Sugar  Candy. 

Sugar  is  very  foluble  in  water  ;  it  fwells  up  in  the  fire,  be- 
htomes  black,  and  emits  a  peculiar  fmell,  known  by  thedenomi- 
"'nation  of  the  fmell  of  caromel. 

Sugar  is  very  much  ufcd  for  domeftick  purpofes.  It  confti- 
tutes  the  balis  of  fyrups  -,  and  is  ufed  at  our  tables  to  dilguife 
the  four  tafte  of  fruit  and  vegetable  juices.  It  corrects  the  bit- 
ternefs  of  coffee  ;  and  ferves  as  the  vehicle  in  a  great  number  of 
pharmaceutical  preparations. 

Sugar  is  an  excellent  food;  and  it  is  merely  an  old  prejudice 
to  fuppofe  it  produces  worms  in  the  bowels  of  children. 

It  is  now  feveral  years  iince  the  celebrated  Bcrgmann  taught 
v^  to  extract  a  peculiar  acid  from  fugar,  by  combining  the  oxi- 


J^j$^  Comhirtattofis  of  (hcalk\  Acid, 

gene  of  die  nitride  acid  with  one  of  its  conftituent  principlfet, 
The  difcovery  of  the  acid  of  fugar  was  coniigned  in  a  the% 
fnaintained  at  Upfal,  the  i3thof  JunCi  1776,  by  M.  Arvidfbn^ 
under  the  prefidency  of  Bergmann. 

To  make  the  acid  of  fugar,  or  oxalick  acid,  nine  parts  of  thfe 
tiitrick  acid,  with  one  of  fugar,  are  put  into  a  retort.  A  gcnv 
tie  heat  is  applied,  to  affift  the  a£lion  of  the  acid  ;  which  is  rap- 
idly decompofcd  upon  the  fugar,  with  the  difengagement  of  k 
confiderabie  quantity  of  nitrous  gas.  When  the  decompofition 
incompleted,  the  dillillation  is  continued  on  a  fand  bath,  till  th^ 
refidue  is  fafficiently  concentrated.  It  is  then  fuffered  to  cool  \ 
and  beautiful  cryftals  are  formed,  which  may  be  taken  out,  and 
tiave  the  figure  of  a  tetrahedral  prifm  terminating  in  a  dihedral 
fummit.  By  a  farther  concentration  of  the  liquor  in  which  tht 
scid  has  cryftallizedj  more  of  thefe  cryftals  may  be  obtained, 
^hefe  feveral  products  of  cryftals  are  then  to  be  difTolved  in  pure 
Water,  and  again  cryftallized,  to  feparate  them  from  any  admix- 
ture of  nitrick  acid  that  may  adhere  to  them.  This  acid  wat 
formerly  thought  to  be  a  modification  of  the  nitrick  acid  ;  and 
Bergmann  xvas  under  the  neceftiry  of  entering  into  a  confidera-t 
ble  detail  of  reafoning,  to  remove  every  doubt  on  the  fubje£t. 
But  the  kno^vledge  \Xre  at  prefent  poflefs  refpefling  the  conftit* 
Uent  pririciples  of  the  nitrick  acid,  and  the  great  number  of  phe- 
Bomena  of  this  kind  which  it  exhibits  when  made  to  a£t  on  va- 
rious fubftances,  render  it  uiinecelTary  for  us  to  enter  into  this 
confideratioii. 

Cold  Water  difTolves  half  its  Weight  of  this  acid,  and  bdiling 
«*aier  takes  up  its  own  weight. 

This  acid,  combined  with  pot-afli,  forms  a  fait  in  prifmatick, 
hexahedral  flattened  rhomboidal  cryftals,  terminating  in  dihe- 
<dral  fUmmits.  In  order  that  cryftallization  may  take  place. 
It  is  neceifary  that  one  of  the  component  parts  fhould  be  in  el- 
cefs.     This  fait  is  very  foluble  in  water. 

The  fame  acid  forms  with  foda  a  fait  which  is  very  difficult 
to  be  brought  to  cryftallize,  and  which  converts  fyrup  of  violets 
to  a  green. 

This  acid,  potired  upon  ammoniack,  affords  by  a  flight  evap- 
oration very  beautiful  tetrahedral  prifmatick  cryftals,  termina- 
ting in  dihedral  fummits  :  one  of  whofc  faces  is  larger  thah  the 
other,  fo  that  it  occupies  three  angles  of  the  extremity.  See  mj 
Memoirs  of  Chemiftry. — This  fait  is  of  great  ufe  in  the  analy- 
lis  of  mineral  waters.  It  inftantly  (hows  the  prefence  of  any 
fait  with  bafis  of  lime,  becaufe  the  oxalate  of  lime  is  infoluble 
in  water. 


Zait  and^  Acid  of  Barret  ^j^ 

The  acid  of  ftigar,  or  oxalick  acid,  attacks;  amlv  dtffolvies,  moft 
t>f:  the  metals  :  but  its  adlion  upon  the  oxides  is  ftronger  tbait 
upon  the  metals  themfelves  j  and  it  takes  the  oxides,  from  theiu 
true  folvents.  In  this  way  it  is  that  it  precipitates  die  iron  &om 
a  folution  of  the  fulphate  of  iron,  in  a  fubftance  of  the  ino^ 
beautiful  yellow  colour,  which  maybe  ufed  in  painting* 

It  precipitates  copper  in.  the  form  of  a  white  powder^  wiiich 
becomes,  of  a  beautifullight  green  by  drying. 

^nc  is  precipitated  of  a  white  colour. 

This  acid  likewife  precipitates -mercury  and  fiJv^r^  but  not  till 
sifter  feveral  hours  (landing. 

All  account  of  the  combinations  of  this  acid  with  various  ba» 
fesL  may  be  feen  in  Bergmann's  treatife. 

This  acid  may  be  extra6ted,  by  the  a<^ion  of  nitrick  acid 
from  a  number  o£ vegetable  fubftances,  fuch  as  gums,  honey^ 
ftarch,  gluten,  or  alcohol  \  and  from  feveral  animal  fubftances, 
apcording  to  tlie  difcovery  of  M.  Burthollet,  fuch  as  filk,  wool, 
;|nd  lymph. 

M.  de  Morveau,  who  has  made  a  very  valuable,  feries.  of  ex- 
periments on  the  acid  offugar,  has  proved  that  the  whole  pf  the 
lugar  does  not  enter  into  the  formation  of  the  acid,  but  only 
one  of  its  principles  ;  and  he  afhrms  that:  it  is.  an.  attenuated  oil 
which  exifts  in  a  variety  of  fubftances. 

Since|it  has  been  afcertained,  from  the  experimentsof-Seheelc^ 
"Weftrumb,  Hermftadt,  and  others,  that  the  acid  t)f  the  fait  of 
ibrrel  does  not  at  all  differ  from  that  offugar,  they  have  been>  ac- 
cordingly confounded  under  the  fame  denomination  ;  and  that 
fait  which  is  known  in  commerce  by  the  name  of  <>alt'Of  Socirel, 
is,an  acidulous  oxalate  of  pot-afti. 

The  fait  of  forrel  is  made  in  Switzerland,  in  the  Hartz,  in 
the  forefts  of  Thuringia,  in  Swabia,  and  elfewhere.  It  is  ex- 
trafted  from  the  juice  of  the  forrel  called  Alleluya.  Juncker^ 
Boerhaave,  Margraff,  and  others,  have  defcribed  the  procefs  u- 
fed  for  its  extradlion.  The  juice  of  forrel  is  expreffed,  diluted 
with  water,  filtered,  and  evaporated  to  the  confiftence  of  cream. 
It  is  then  covered  with  oil,  to  prevent  its  fermentation,  and  left 
in  a  cellar  for  fix  months. 

According  to  M.  Savary,  fifty  pounds  of  this  plant  afford  five 
and  twenty  of  juice,  from  which  no  more  than  two  ounces  and 
a  half  of  the  fait  are  obtained.  Six  parts  of  boiling  water 
dilTolve  one  of  the  fait.  It  appears  to  cryftailize  in  paralielopi- 
pedons,  according  to  De  Lifle. 

Margraff  obferved  that  the  nitrick  acid,  dijefted  upon  fait  o£ 
forte),  afforded  nitre. 


4^4  ^"^^  ^f  ^^^c^» 

Calcareous  earth  has  the  property  of  difengaging  the  alkali  ; 
and  in  this  operation  the  carbon ick  acid  of  the  chalk  unites  with* 
the  alkali  of  the  fait  and  forms  a  carbonate  of  pot-afh. 

Salt  of  forrel  unites  with  other  bafes  without  yielding  its  own,- 
fo  that  the  refults  are  triple  falts.  See  the  Encyclopedic  Meth- 
odique,  torn.  i.  p.  200,  201. 

The  pure  oxalick  acid  may  be  obtained  by  diftillation  of  this 
fait,  as  Mr.  Savary  infonns  us ;  or  otherwife  by  depriving  it  of 
its  alkali  by  means  of  fulphurick  acid,  and  diftillation,  according 
to  Wiegleb's  method  :  pr  otherwife  by  the  procefs  of  Scheele, 
which  confifts  in  faturating  the  exccfs  of  acid,  with  ammoniack, 
and  pouring  the  nitrate  of  barytes  into  the  folution.  The  nitrick 
acid  then  feizes  the  two  alkalis,  while  the  oxalick  acid  unites 
with  the  harytes,  and  falls  down.  The  barytes  is  afterwards 
taken  from  its  combination  by  the  fulphurick  acid,  and  leaves  the 
oxalick  acid  difengaged. 

Scheele  has  likewife  propofed  another  method  of  obtaining 
the  pure  oxalick  acid.  It  confifts  in  dillblving  the  fait  in  water, 
and  pouring  in  a  folution  of  fait  of  faturh.  A  precipitate  is 
formed ;  and  the  fupernatant  liquor  contains  the  alkali  of  the 
fait  of  forrel,  united  with  a  portion  of  the  vinegar.  The  precip- 
itate is  then  waftied,  and  fulphurick  acid  poured  on,  which 
unites  with  the  lead  :  and,  by  filtering  and  evaporating,  the  ox- 
alick acid  is  obtained  in  cryftals,  fimilar  to  thofe  of  the  acid  of 
fugar. 

Scheele  has  proved  the  identity  of  the  acid  of  fait  of  forrel 
with  that  which  is  extracted  from  fugar.  He  diflblved  the  acid 
of  fugar  to  faturation  in  cold  water,  and  into  this  he  very  grad- 
ually poured  a  well-faturated  folution  of  pot-afh.  During  the 
cfFervefcence,  he  obferved  that  fmall  tranfparent  cryftals  were 
formed,  which  were  found  to  be  a  true  fait  of  forrel. 

Mr.  Hoffman  has  proved  that  the  juice  and  the  cryftals  of  the 
berberris  vulgaris  conrain  t\\Q  oxalick  acid  combined  with  pot- 
alh.  And  the  celebrated  Scheele  has  proved  that  the  earth  of 
rhubarb  is  a  combination  of  the  oxalick  acid  with  lime. 


ARTICLE    IX. 

Concerning  the  Vegetable  Acids. 

The  vegetable  acids  have  been  long  confidered  to  be   weaker 
than  the  others  ;  and  this  opinion  was  adhered  to   until    it    was 
obferved  that  the  oxalick  acid  fcized  lime  from    the    fulphurick 
acid.     The  principal  characters  which  may  ferve  to  eftablifh   a 
line  of  diftinction  between  the  vegetable  acids  and  others   are — 


Ths  Vegeiahle  Acids.  Afi^ 

I.  Their  volatility  ;  for  there  are  none  which  do  not  rife  with 
a  moderate  heat.  2.  Their  property  of  leaving  a  coaly  refidua 
after  combultion,  and  of  emitting  an  empyreumatick  fmell  in 
hurning.  3.  The  nature  of  their  acidifiable  bafe  which  is  in 
general  oily. 

But  are  all  the  vegetable  acids  ideHtical  in  their  nature  ?  And 
may  they  not  be  confidered  as  modifications  of  one  and  the  fam« 
acids  ? 

If  we  depend  on»the  principle  laid  down  by  the  celebrated 
Monro,  who  confiders  no  acids  as  identical  but  fuch  as  form  ex-f 
a<5^1y  the  fame  falts  with  the  fame  bafe  (Phil.  Tranf.  vol.  Ivii.  p. 
479,)  there  will  be  no  queftion  but  th^at  all  the  known  acida 
ought  to  be  confidered  as  very  different  from  each  other.  But 
this  method  of  proceeding  appears  to  me  to  be  erroneous  ;  be- 
caufe  in  this  cafe  the  various  degrees  of  faturation  of  the  fame 
principle  with  oxigene,  would  eltablifh  various  kinds  of  acids. 
The  flow  or  rapid  combufiion  of  phofphorus  caufes  fufBcient  mod- 
ifications in  the  acid  to  afford  different  phofphorick  falts,  accord- 
ing to  the  lixperiments  of  Mell'.  Sage  and  Ijavoifier.  But  ought 
we  on  this  account  to  admit  of  two  fpecies  of  phofphorick  acid  ? 
By  following  tlie  method  of  Monro,  which  is  that  of  mod 
chemifls,  we  might  multiply  the  vegetable  acids  to  infinity  ;  but 
by  collating  tlie  experiments  of  Hermftadt,  Crell,  Scheele,  Wef- 
trumb,  Berthollet,  Lavoifier,  &c.  we  may  obferve  that  the  veget- 
able acids  are  merely  modifications  of  one  or  two  primitive  acids* 

1.  Scheele  obtained  vinegar  by  treating  fugar  and  gum  with 
manganefe  and  the  nitrick  acid.  He  obferved  that  tartar  had 
the  fame  effedl:  or  habitude  as  fugar  in  the  folution  of  manga- 
nefe  by  the  nitrick  acids  ;  and  that  vinegar  was  found  after  tl^<? 
decompofition  of  etiier. 

2.  Mr.  Creil,  by  boiling  the  refidue  of  nitrick  alcohol  (dulct- 
fied  fpirit  of  nitre)  with  tr* uch  nitrick  acid,  taking  care  to  adapt 
veflels  to  condenfe  the  vapour,  and  faturatin^  what  came  over 
with  alkcili,  obtained  nitrate  and  the  acetate  of  pot-alh.  The 
latter  being  feparated  by  alcohol,  gives  out  its  vinegar  by  the 
ufual  treatment. 

3.  The  fame  chemift,  by  boiling  the  pure  oxalick  acid  with 
twelve  or  fourteen  parts  of  nitrick  acid,  obferved  that  the  for-» 
mer  difappears  ;  and  the  receiver  is  found  to  contain  nitrous 
acid,  acetous  acid,  carbonick  acid,  and  nitrogenous  gas  \  and  in 
the  retort  there  remains  a  little  calcareous  earth.* 

*  There  being  an  obvious  overnght  in  the  author's  paragraph,  I  have 
iken  tlie  liberty  to  rellore  the  paflagc  from  Creli's  original.     Journal  de 
Phyf.  Qt\.  1785,  quoted  by  Dr.  Beddoes  at  the  end  of  the  Erglifli  JraDf- 
iatio>i  of  Scheeie's  E^ays.    London,  17^0.   T. 

3.-.L 


466  The  Vcgetahle   Acids, 

4.  By  faturating  the  refidue  of  nitrick  alcolrol  with  chalk,  art 
infoluble  fait  is  obtained  ;  which,  treated  with  the  fulphurick 
acid  affords  a  true  tartareous  acid. 

5.  By  boiling  one  part  of  oxalick  acid  with  one  part  and  a 
half  of  manganefe,  and  a  fufficient  quantity  of  nitrick  acid,  the 
manganefe  is  almoft  totally  diffolved,  and  vinegar  with  nitrous 
acid  pafs  into  the  receiver. 

6.  By  boiling  tartareous  acid  and  manganefe  with  the  fulphu- 
rick acid,  the  manganefe  is  diffolved,  and  vinegar  with  fulphu- 
rick acid  are  obtained.  •■ 

7.  By  digeiting  for  feveral  months  the  tartareous  acid  and 
alcohol,  the  whole  becon;jes  changed  into  vinegar  ;  and  the  air 
of  the  veffels  is  found  to  confift  of  carbonick  acid  and  nitrogene 
gas. 

From  thefe  fa£ls  Creil  concludes  that  the  tartareous,  oxal- 
ick, and  acetous  acids,  are  merely  modifications  of  the  fame 
acids. 

In  the  Journal  de  Phyfique  for  September  1787,  isinferted  a 
memoir  of  M.  Hermftadt  on  the  converfion  of  the  oxalick  and 
tartareous  acids  into  acetous  acid. 

1.  By  caufmg  the  oxigenated  muriatick  acid  to  pafs  through 
very  pure  alcohol,  ether  is  produced  ;  and  the  oxigenated  acid 
refumes  its  character  of  ordinary  muriatick  acid.  The  ether  by 
diftillation  affords — i.  Ether.  2.  Muriatick  alcohol.  3.  Vinegar 
mixed  with  regenerated  muriatick  acid. 

2.  Nitrick  acid  diftilled,  for  feveral  fucceffive  times,  from 
the  oxalick  and  tartareous  acids,  converts  them  totally  into  ace- 
tous acid. 

3.  Two  parts  of  oxalick  acid,  three  of  fulphurick  acid,  and 
four  of  manganefe,  mixed  with  one  part  and  a  half  of  water, 
and  diftilled  together,  afford  acetous  acid,  which  requires  to  be 
recohobated  and  rediiliiled  to  become  very  pure. 

4.  If  the  fulphurick  acid  be  boiled  upon  the  oxalick  or  the 
tartareous  acid,  thefe  tv^o  laft  are  not  deftroyed,  as  Bergmann  . 
thought,  but  they  are  converted  into  acetous  acid.  It  is  prov- 
ed, by  the  experiments  of  M.  Hermftadt,  that  the  fulphureous 
acid  in  the  receiver,  when  ether  is  made,  is  mixed  with  much 
acetous  acid. 

It  appears  therefore  to  be  proved  that  the  tartareous,  oxalick, 
and  acetous  acids  differ  from  each  other  only  in  the  proportion 
of  oxigene. — In  the  above  experiments  the  mineral  acids  are  al- 
ways decompofed  ;  and, "by  faturating  the  radical  with  their  ox- 
igene, they  conftantly  form  the  acetous  acid.  If  the  faturation 
be  not  exaft,  the  refult  is  either  oxalick  or  tartareous  acid  : 
which  is  ftill  more  proved  by  a  fine   experiment  of  M.  Herm. 


P^rotnuciIagif20Us  Add.  46^ 

ftadt.  If  three  parts  of  fuming  nitrick  acid  be  put  into  the  pneu- 
matick  apparatus,  and  a  large  jar  be  adapted,  6lled  with  water  j 
if  then  one  part  of  good  alcohol  be  poured  in,  by  a  little  at  a 
time,  the  mixture  will  be  heated  every  time  a  drop  of  the  alcohol 
is  let  fall,  and  a  great  quantity  of  bubbles  will  rife  into  the  re- 
ceiver. When  the  operation  is  ended,  if  care  be  taken  to  col- 
lect the  gas,  it  v/ili  be  found  toconfill  of  nitrous  gas,  a  fmall 
quantity  of  carbonick  acid,  and  about  a  twelfth  part  of  the  ace- 
tous air  of  Prieftly.  The  refidue  aaords  oxalick  acid  and  ace- 
tous acid.  The  oxalick  acid  difappears  if  the  operation  be  con- 
tinued ;  ether  is  formed,  and  the  acetous  acid  remains,  and  be- 
comes more  in  quantity. 

Mr.  Hermftadt  has  likewife  fucceeded  in  converting  the  zc- 
ids  of  tamarinds,  of  citrons,  of  marc  of  grapes,  the  juice  of 
plums,  apples,  pears,  goofeberries,  berberries,  forrel,  and  others 
into  the  oxalick,  tartareous,/and  acetous  acids. 

From  all  thefe  experiments  it  appears,  that  the  oxigene,  com- 
bined with  a  principle  of  alcohol,  forms  the  oxalick  acid  ;  and 
that  a  more  accurate  laturation  of  this  principle  with  oxigene 
forms  the  tartareous  and  acetous  acids. 

M.  Lavoifier  has  proved  that  the  known  vegetable  acids  do 
not  differ  from  each  other  but  in  the  proportion  of  hydrogene 
and  carbone,  and  in  their  degree  of  oxigenation. 

I  have  proved  (in  the  Memoirs  of  the  academy  of  Sciences 
of  Paris  for  the  year  1786)  that  water  impregnated  with  the  gas 
difengaged  from  the  juice  of  grapes  in  fermentation,  pafles  the 
ilate  of  acetous  acid. 

It  apppears  that  the  vegetable  acids  may  be  confidered  in  two 
very  different  points  of  view.  Mofl  of  them  exift  in  the  plant 
itfelf  ;  but  the  properties  and  acid  characters  are  difguifed  by 
their  combination  with  other  principles,  fuch  as  oils,  earths,  al- 
kalis, &c.  On  the  other  hand,  fdveral  acids  arc  extra(fled 
from  vegetables,  which  did  not  exiit  in  nature.  In  this  cafe  the 
plant  contained  only  the  radical,  and  the  reagent  with  which  it  is 
treated  affords  the  oxigene. 

The  mere  diilillation  of  mod  vegetable^  is  fufHcient  to  devel- 
ope  an  acid,  which  was  difguifed  by  oily,  alkaline,  or  earthy 
fubftances. 

I.  The  peculiar  acid  called  the  Pyro-mucilaginous  acid,  is 
afforded  by  diilillation  by  all  plants  which  contain  a  faccharine 
juice. 

For  the  preparation  of  this  acid,  the  quantity  of  fugar  intend- 
ed to  be  operated  upon  is  put  into  a  very  capacious  retort  (the 
large  (ize  being  requifite,  becaufe  the  matter  fwells  up),  and  a 
receiver  fufHciently  ample  to   condenfe  the  vapour  is  adapted. 


46S  ♦  Pyrohgheoui  Adld* 

an  aftotii{King  quantity  of  carbonick  aeid  and  hydrogens  gas 
sre  difengaged  by  the  firfl  impreffion  of  the  fire.  A  browrt 
fluid  remains  in  the  receiver,  moft  of  which  confids  of  a  weak 
acid,  colouring  blue  paper,  and  rendered  dark  by  a  portion  of 
oil.  The  retort  contains  a  fpongy  coal.  M.  Schrickel  advi- 
fes  the  rectification  of  the  prodacSi  of  the  firft  diftillation  from 
clay,  in  order  to  purify  the  acid  :  but  M.  de  Morveau  has  re- 
diltilled  it  without  intermedium  ;  and  the  acid  he  obtained  had 
only  a  llight  yellow  tinge.  Its  fpecifick  gravity  was  1.0115, 
the  thermometer  (landing  at  twenty  degrees. 

As  this  acid  rifes  at  the  fame  temperature  as  water,  it  is  not 
poflible  to  concentrate  it  by  didillation.  But  this  purpofe  may 
be  effe6led  by  freezing  ;  and  in  this  manner  it  was  that  M. 
Schrickel  prepared  the  acid  he  made  ufe  of  to  afcertain  its  com- 
binations. 

This  acid  cxlfls  in  all  bodies  capable  of  pafTnig  to  the  fpiriru- 
ous  fermentation,  \Vhile  they  contain  only  the  radical  of  the  ox- 
alick  acid.  The  pyromucilaginous  acid  is  combined  in  the  veg- 
etable with  oils  in  the  faponaceous  ftate. 

This  concentrated  acid  has  a  very  penetrating  tafle.  It 
firongly  reddens  blue  colours.  If  it  be  expofed  to  heat  in  open 
v.flels,  it  is  diflipated,  and  leaves  only  a  brown  fpoc.  If  it  be 
heated  in  clofed  veiTels,  it  leaves  a  more  confiderable  refidue,  of 
the  nature  of  the  coal  of  fugar. 

This  acid  fpecdily  attacks  the  earthy  and  alkaline  carbonates, 
and  forms  falts  differing  from  the  oxalates.  According  to  Mr. 
Schrickel,  it  diffolves  gold.  He  afhrms  that  he  made  the  exper^ 
iment  in  the  prefence  of  Fred.  Aug.  Cartheufer.  Lemery  had 
afTerted  that  the  fpirit  of  honey  poflefFed  this  property  \  and  this 
opinion  is  likewife  fupported  in  the  works  of  Depre,  Etmuller, 
&;c.  Neumann  oppofed  the  af^'ertion  ;  and  the  experiments  of 
M.  de  Morveau  confirm  thofe  of  this  laft  chemifl:. 

Silver  is  not  attacked  by  the  pyromucilaginous  acid;  but 
inercury  combines  with  it  by  virtue  of  a  long  digelHon.  Con- 
fult  de  Morveau. 

This  acid  cofrodes  lead,  and  forms  a  very  flyptick  filt  in  long 
cryftals.  With  copper  it  forms  a  green  folution.  It  partly 
diifolves  tin,  and  aiibrds  green  cryftals  with  iron. 

2.  The  denomination  of  the  Pyroligneous  Acid  has  been  giv- 
en to  the  dcid  obtained  by  diftillation  from  wood.  It  has  been 
long  known  that  the  hardeft  woods  afford  an  acid  principle,  mix- 
ed with  an  oil,  which  partly  difguifes  its  properties  ;  but  no 
one  had  directly  attended  to  a  determination  of  the  habitudes  of 
this  acid,  till  PrI.  Goettling  publillied,  in  Cre'l's  Annals  for 
1  779,  a  feriesof  refearchcs  on  the  acid  of  wood,  and  the  ether  it 
^fiords. 


j^ad  of  Lemons,  ^6^ 

M.  de  Morveau,  to  obtain  this  acid,  diftilled  fmall  pieces  of  ve- 
iry  dry  beech  in  an  iron  retort,  by  a  reverberatory  furnace.  He 
changes  the  receiver  when  the  oil  begins  to  rife,  and  re£lifies 
his  produft  by  a  fecond  diflillation.  Fifty-five  ounces  of  very 
dry  chips  afforded  feventeen  ounces  of  redified  acid,  of  an  am- 
ber colour,  not  at  all  empyreumatick  ;  whofe  fpecifick  gravity, 
compared  with  that  of  diftilled  water,  was  as  49  :  48. 

This  acid  ftrongly  reddens  blue  vegetable  colours.  One  ounce 
required  twenty-three  ounces  and  a  half  of  lime  water  for  its 
complete  faturation. 

It  fupports  the  a£lion  of  heat  very  well  when  it  is  engaged  in 
an  alkaline  bafe  j  but  by  a  ftrong  heat  it  is  burned,  like  all 
the  vegetable  acids. 

It  does  qct  precipitate  martial  folutions  of  a  black  colour. 
It  unites  with  alkalis,  earths,  and  metals.     It    does    not  give 
up  lime  or  barytes  to  combine  with  cauflick  alkalis. 

The  a6tion  of  the  pyroligneous  acid  upon  metallick  fubftan- 
ces,  and  upon  alumine,  may  be  compared  with  that  of  the  acet- 
ous acid,  and  appears  to  follow  the  fame  order. 

This  acid  diiiblves  near  twice  its  weight  of  the  oxide  of  lead. 
3.  The  citrick  acid.  Lemon  juice  is  in  a  difengaged  ftate  in 
the  fruit,  and  exhibits  its  acid  properties  without  any  prepara- 
tion. This  acid  is  neverthelefs  always  mixed  with  a  mucilagin* 
ous  principle,  capable  of  altering  by  fermentation.  Mr.  Geor- 
j^ius  has  defcribed,  in  the  Memoirs  of  Stockholm  for  the  year 
J  7  75,  a  method  of  purifying  this  acid  without  changing  its  prop- 
erties. He  fills  a  bottle  with  lemon  juice,  clofes  it  with  a  cork,* 
and  preferves  it  in  a  cellar.  The  acid  was  preferved  for  four 
years,  without  corrupting.  The  mucilaginous  parts  had  fallen 
clown  in  flocks  ;  and  a  folid  cruft  was  formed  beneath  the  cork, 
the  acid  itfelf  having  become  as  limpid  as  water.  To  de- 
phlcgmate  the  acid,  he  expofes  it  to  froft  •,  and  obferves  that  the 
temperature  ought  not  to  be  too  cold,  becaufe  in  that  cafe  the 
M'holc  would  become  folid  j  and  though  the  acid  would  thaw 
the  firft,  it  would  always  be  productive  of  fome  inconvenience. 
In  order  to  concentrate  it  to  better  advantage,  the  ice  muft  be 
feparated  as  it  forms.  The  firft  ice  U  taftelefs,  and  the  laft  is 
rather  four  •,  and  by  this  means  tlie  liquor  is  reduced  to  half. 
The  acid  thus  concentrated  is  eight  times  as  ftrong,  two  gros  on- 
ly being  required  to  faturate  one  gros  of  pot-afh. 

The  citrick  acid,  when  thus  purified  and  concentrated,  may 
he  kept  for  feveral  years  in  a  bottle  -,  and  ferves  for  all  ufes,  noi: 
excepting  tliat  of  miking  lemonade. 

The  chernlfts  in  general  who  have  examined  the  combinations 
©f  the  citrick  acid,  have  ufcd  it  in  its  original  ftate,  fembarrafled 


470  ^i^cid  of  Apples, 

with  JtB  mucilaginous  principle.  Such  is  the  refult  of  the  ex- 
periments of  M.  Wenzel,  who  obtained  only  gummy  products. 
But  M.  deMorveau  having  faturated  the  purified  acid  with 
cryftals  of  pot-afh,  found  a  non-dehquefcent  fait  at  the  end  of  i, 
certain  time. 

The  combinations  of  this  acid  are  little  known. 

4.  The  malick  acid. — This  acid  was  announced  by  Scheele  in 
17S5,  aiid  publifhed  in  Crell's  Annals.  In  order  to  obtain  it, 
the  juice  of  apples  is  faturated  with  alkali,  and  the  acetous  folu- 
ticn  of  lead  is  poured  in  until  it  occafions  no  more  precipitate* 
The  precipitate  is  then  edulcorated,  and  fulphurick  acid  poured 
on  it  until  the  liquor  has  acquired  a  frcfh  acid  talte,  without  any 
mixture  of  fweetnefs.  The  whole  is  then  filtered,  to  feparate 
the  fulphate  of  lead.  This  acid  is  very  pure,  always  in  the  flu- 
id ftate,  and  cannot  be  rendered  concrete. 

It  unites  with  the  three  alkalis,  and  forms  deliquefcent  neu- 
tral falts.  When  faturated  with  lime,  it  affords  fmall  irregular 
cryftals,  which  are  ioluble  only  in  boiling  water.  Its  habitude 
with  barytes  is  the  fame  as  with  lime. 

With  alumine  it  for.ms  a  neutral  fait  of  fparing  folubiHty  in 
•water,  and  with  magnefia  a  deliquefcent  fait. 

It  diiFers  from  the  citrick  acid — i.  Becaufe  the  citrick  acid 
■faturated  with  lime,  and  precipitated  by  the  fulphurick  acid,  cryf- 
taliizes  *,  whereas  this  is  not  cryftallizable.  2.  The  malick  acid, 
treated  with  the  nitrick  acid,  affords  the  oxalick  acid  ;  the  citrick 
docs  not  afford  it.  3.  The  citrate  of  lime  is  almoft  infoluble  in 
boiling  water;  the  malate  of  lime  is  more  foluble,  4.  The  mal- 
ick acid  precipitates  the  folutions  of  the  nitrates  of  lead,  of  mer- 
cury, and  of  filver  ;  but  the  citrick  acid  produces  no  change. 
5.  If  the  folutions  of  the  nitrate  of  ammoniack,  and  malate  of 
lime,  be  boiled  together  for  an  inftant,  the  latter  fait  is  decom- 
pofed,  and  nitrate  of  lime  falls  down  ;  which  proves  that  the 
afhnity  of  tlie  malick  acid  with  lime  is  weaker  than  that  of  the 
nitrick. 

The  celebrated  Scheele,  who  has  rendered  us  acquainted  with 
this  acid,  has  publifhed  the  following  table  of  the  fruits  which 
sflbrd  this  acid,  either  pure  or  mixed  v.-ith  other  acids, 

The  expreffed  juices  of  the  fruits  of 

Berberries  vulgaris,  the  barberry  tree,  1 

Sanibucus  nigra,  Eider,  I  Afford  much    malick    acid 

Prunas  fpinofa,  Sloe,  \     and  little  or  none  of  the 

Sorbus  aucup,  Service,  |      ciirick  acid. 

Prunui  domellick.  Garden  plum,  J 


Acid  of  Vegetables,  j^%x 

ftibes  groffalaria,  the  Hairy  Goofeberry,     ") 
Kibes  rubrum,  the  currant,  | 

Vaccinium  i^rtellu.  WhortlAerry,  j  ^^  ^^^^.^  ^^^^ 

^ru?src~  "-""•       r  T "' "'"' "' ""  °^- 

Fragaria  veica,  Strawberry,  j 

Kubus  chamemgurs,  Bilberry,  j 

Rubus  idasus,  Rafpberry,  J 

VacciniuiTi  oxycacos,  Marfhwhortle,     "j 

Vaccinium  Vitis  Idaea,  j 

Prunus  padas.  Bird's  Cherry,  i  Contain  much  citrick,  and  little 

Solanum  dulcamara,  j      or  none  of  tiieraaligk  acid. 

Clynolbatus,  Eglantine,  ', 

Citrus,  Citron  or  Lemon,  j 

According  to  the  fame  chemift,  the  juice  of  green  grapes,  as 
well  as  that  of  tamarinds,  contains  only  the  acid  of  citrons. 

Schecle  haslikevvife  proved  the  exigence  of  the  malick  acid  int. 
iugar.  If  weak  nitrick  acid  be  poured  on  fugar,  and  difliiled  u\l 
the  mixture  begins  to  turn  brown,  all  the  oxalick  acid  may  be 
precipitated  by  tlie  addition  of  lime-water  ;  and  another  acid 
will  remain,  which  the  lime-water  does  not  precipitate.  To  ob- 
tain this  acid  in  a  ftate  of  purity,  the  liquor  is  faturated  by 
means  of  chalk,  then  filtered,  and  alcohol  added,  which  occa- 
fions  a  coagulation.  This  coagulation,  well  wafhed  in  alcohol, 
is  rediffolved  in  diftilled  water.  The  malate  of  lime  is  decom- 
pofed  by  the  acetate  of  lead  ;  and,  lail  of  all,  the  malick  acid  is 
difengaged  by  the  fulphurick  acid.  The  alcohol  by  evaporation 
leaves  a  fubftance  rather  bitter  than  fweet,  which  is  deliquel^ 
cent,  and  refembles  the  faponaceous  matter  of  lemon  juice.  If  a 
fmall  quantity  of  nitrick  acid  be  dillilled  from  this,  the  malick 
and  oxalick  acids  are  obtained. 

By  treating  various  other  fubftances  with  the  nitrick  acid,  the 
malick  and  oxalick  acids  are  likewife  obtained.  Such  are  gum 
arabick,  manna,  fugar  of  milk,  gum  adragant,  flarch  and  the  fc- 
cula  of  potatoes.  The  extract  of  nut-galls,  the  oil  of  parfley 
feed,  the  aqueous  extrael  of  aloes,  of  coloquintida,  of  rhubarb, 
of  opium,  afforded  not  only  the  two  acids  to  Mr.  Scheele,  but 
likewife  much  refm. 

This  celebrated  chemift,  by  treating  feveral  animal  fubftances 
with  very  concentrated  nitrick  acid,  obtained  the  malick  and  the 
oxalick  acids  from  them.  Fifli  glue,  or  ifniglafs,  white  of  G^gf 
yolk  of  egg,  and  blood,  treated  in  the  fame  manner,  afforded  the 
lame  products. 

There  are  few  vegetables  which  do  not  exhibit  fome  acid  more 
or  lefs  developed.  We  fee,  for  example,  all  fruits,  infipid  at^ 
firft,  become  infenfibly  acid  ;  and  finifti  by  lofing  that  tafte,^ 
and  become  faccharine.  There  are  fome  v.'hich  conftanfly  pre- 
ferve  an  acid  tafte,  and  form  a  particular  clafs. 


47  2  -^i^ids  of  Vtgeiahtes, 

Some  plants  contain  an  acid  principle  difFufcH  through  the 
whole  parenchyma  or  body  of  the  vegetable,  ^uch  are  the  yeU 
low  gilly-flovver,  bardana  or  vvaterdock  ;  filipendula  or  dropwort, 
water  crefles,  the  herb  robert,  &g.  Thefe  plants  fenfibly  red- 
den blue  paper. 

There  are  others  in  which  the  acid  principle  exifts  only  in 
part  of  the  plant  ;  as,  for  example,  in  the  leaves^  of  the  greater 
valerian,  the  fruit  of  the  winter  cherry  and  of  the  cornel  tree, 
the  bark  of  burdock,and  the  root  of  ariftolochia  or  birthworth. 

Mr.  Monro  communicated  fome  experiments  to  the  Royal 
Society  of  London,  in  1767,  which  prove  that  certain  vegeta^ 
bles  contain  acids  nearly  in  a  difengaged  (late,  and  even  fuch  as 
are  the  leaft  promifing  on  a  flight  examination. 

1.  Having  peeled  two  dozen  of  fummer  apples,  and  cut  them 
into  fmall  pieces,  he  poured  water  upon  them,  in  which  he  had 
previoufly  diilolved  two  ounces  of  foda,  and  left  the  whole  to 
ftand  for  fix  days.  The  filtrated  liquor,  evaporated,  and  left  in 
repofe  for  fix  days  more,  afforded  a  beautiful  fait,  in  fmall  round 
tranfparent  plates,  placed  edgewife  on  each  other. 

2.  The  juice  of  mulberries  clarified  with  the  white  of  ^ggi^ 
and  faturated  with  foda,  afforded  a  pulverulent  fait  of  no  regu- 
lar figure  which  by  repeated  folutions  and  evaporations,  at  laft 
produced  long  ci-yflals,  one  kind  being  thin,  and  the  other  thick- 
er, which  crofled^each  other. 

3.  He  obtained  fmall  cubical  or  rhomboidal  cryftals  by  treat- 
ing peacbpes  and  oranges  with  foda. 

4.  The  green  plum  alTorded,  after  feveral  folutions  and  cryf- 
tallizations,  a  neutral  fait,  which  cry  flail  ized  without  evapora- 
tion in  large  hexagonal  plates,  and  partly  in  large  rhombi.  This 
fait  had  a  hot  tafle,  and  was  foluble  in  three  or  four  times  its 
weight  of  cold  v/ater, 

5.  The  red  goofeberry  afforded,  by  evaporation  and  cooling, 
fmall  very  hard  rhomboidal  cryftals,  not  changeable  in  tb.e  air  ; 
whofe  tafte  refembled  that  of  the  fait  produced  by  a  combination 
of  the  acid  citrick  with  the  fame  bafe. 

The  green  goofeberry  produced  a  faline  crufl  formed  of  fmall 
rhomboidal  cryflals,  and  covered  with  their  brilliant  fcales. 

6.  The  green  grapes  aflbrded  Mr.  Monro,  by  repeated  foIu-» 
tions,  a  neutral  fait,  in  fmall  cubical  cryftals,  of  a  rhomboidal  or 
parallelogramick  figure,  lying  upon  and  interfe6ling  each  Of 
ther. 

The  juice  of  hemlock  afTorded  Mr.  Baume  a  fait  in  fmall  ir- 
regular cryftalS;  nearly  taftelefs,  but  leddcniug  the  infufioii  of 
tvirnfole. 


AlkcSs, 


473 


7.  M.  Rinman,  in  his  Hiftory  of  Iron,  places  the  forb^apple 
and  floe  among  the  fubftances  capable  of  corroding  and  cleanf- 
ing  the  furface  of  this  metal,  on  account  of  their  acid. 

"When,  by  the  decompofition  of  certain  vegetables  by  the  ni- 
trickacid,  an  acid  was  obtained  as  the  laft  refult,  it  was  thought 
to  have  cxifted  ready  formed  in  the  vegetable  ;  but  a  more  in- 
timate examination  fliowed  that  the  acid  made  ufe  of  in  this 
operation  was  merely  decompofed,  while  it  deftroyed  the  organ- 
ization of  the  vegetable,  difunited  ihe  combinations  which  re- 
tained the  principles,  and  that  the  oxigenoiis  bafe  of  this  acid, 
by  uniting  with  an  element  of  the  vegetable,  formed  a  particu- 
lar acid.  This  truth  is  deduced  from  the  combined  procefles 
of  M.  Lavoifier,  De  Morveau,  &c. 

It  Is  to  a  fimilar  caufe  that  we  ought  to  attribute  the  forma- 
tion of  the  acetous,  the  carbonick,  and  other  vegetable  acids  ; 
and  even  the  rancidity  of  oils,  and  the  alteration  to  which  fome 
other  principles  of  the  vegetable  kingdom  are  fubje^l.  In  thefe 
cafes  the  ait  affords  the  oxigene  which  becomes  fixed  in  the 
plant,  and  gives  it  an  acid  nature. 

'The  oxalick  acid  does  not  exift  ready  formed  in  fugar,  neither 
is  the  camphorick  acid  ready  formed  in  camphor.  The  fame 
may  be  obferved  of  feveral  other  acids  which  are  extracted  by 
means  of  certain  acids  decompofed  by  being  treated  with  vege- 
table fubftances.  We  fliall  fpeak  of  thefe  acids  when  we  come 
to  treat  of  their  radical  principles. 


ARTICLE  X. 

Concerning  Alkalis. 

Alkali  exifls  ready  formed  in  plants.  Duhamel  and  GrofTe 
have  proved  that  it  might  be  extracted  by  means  of  acids.  Mar- 
grafFand  Roucllc  have  added  new  proofs  in  fupport  of  the  af- 
fertions  of  thefe  chemifts.  They  have  obferved,  from  their  ex- 
periments, that  the  alkali  exifted  in  a  difengaged  Hate  in  veget- 
ables :  but  thefe  experiments  proved  at  mofl  that  their  flate  of 
combination  is  fuch  that  it  may  be  broken  by  the  mineral  acids. 

The  alkali,  in  fome  inflances,  is  nearly  in  a  difengaged  flate  j 
for  it  is  found  in  combination  with  carbonick  acid  in  the  helian- 
thus  annuus.  But  the  alkali  of  plants  is  often  combined  with 
the  oily  principle. 

When  it  is  required  to  extract  the  alkali  from  a  vegetable 
fubllancc,  all  the  principles  with  whicli  it  may  be  united,  are 
«4eftroved  bv  fire  -,  and  it  is  cleared  from  the  refidues  of  the 
3...M 


474  JlkaUs  and  other  Salts ^  afforded  by  Plants, 

combuftion  by  lixiviation.  This  is  the  procefs  ufed  to  make 
the  impure  alkali,  called y??////,  as  we  have  already  obferved. 

If  wood  remains  a  long  time  under  water,  it  is  deprived  of 
its  property  of  affording  an  alkali  by  combuftion  i  becaufe  the 
water  diflblves  the  compounds  which  may  contain  it. 

Marine  plants  afford  an  alkali  of  another  nature,  known  hj 
the  name  of  Soda.  Vegetables  poffefs  the  power  of  decompo- 
fmg  common  Tea  fait,  and  retaining  its  alkaline  bafe.  All  infip- 
id  plants  are  capable  of  affording  more  or  lefs  of  foda  if  they  be 
railed  on  the  fea  coalt  ;  but  they  perilh  there  in  a  fhort  time* 

Ammoniack  is  likewife  found  in  plants.  The  glutinous  part 
of  gramineous  vegetables  contains  it,  and  gives  it  out  to  the  ni- 
trick,  muriatick,  and  other  acids,  according  to  M.  Pouletier  : 
and  nothing  more  is  required  than  to  triturate  the  effsntial  fait 
of  wormwood  with  fixed  alkali,  to  feparate  the  volatile.  This 
alkali  appears  to  be  one  of  the  principles  of  the  tetradynamia,  %$ 
thefe  afford  it  by  fmiple  diftillation. 

Alkalis  likewife  exift  in  plants  in  the  ftate  of  neutral  falts* 
They  are  combined  with  the  fulphurick  acid  in  old  borage  and 
in  fomc  aftringent  plants.  The  fulphate  of  pot-afli  appears  to 
exifl  in  almoft  all  vegetables,  as  the  pot-afh  contains  more  or  lefs 
of  it  ;  and  the  anaiyfis  of  robacco  has  afforded  me  a  confiderable 
quantity. 

Tamarifck  affv^rds  the  fulphate  of  foda  In  fuch  abundance^ 
that  by  extiaclingit  from  the  afhes  of  this  plant,  it  can  be  af- 
forded in  very  beautiful  and  pure  cryftals  at  thirty  livres  the 
quintal. 

The  greater  turnfole,  parietaria,  and  borage  contain  nitrate  of 
pot-afli. 

The  muriates  of  foda  and  of  pot-adi  are  afforded  by  marine 
plants. 

We  Hkevvife  find  the  alkalis  combined  with  the  acids  of  veget- 
ation, fuch  as  the  oxalick,  the  tartaveous,  and  other  acids. 

It  appears  that  the  feverai  falts  are  the  produdls  of  the  veget- 
ation, and  peculiar  effecl:  of  the  organization,  of  vegetables. 
Two  plants  which  grow  in  the  fame  foil,  afford  very  different 
falts  ;  and  each  plant  conflantly  affords  the  fame  kind.  Be- 
fides,  tliis,  Homberg  obferved  (Mem.  Acad.  Par.  i66y)  that  the 
fame  falts  were  developed  by  plants  growing  in  earths  previoufly 
■well  waflied,  and  afterwards  watered  with  dillilled  water. 

We  may  therefore  clafs  falts  among  tlie  principles  of  vegeta- 
bles, and  no  longer  confic'er  them  as  accidentally  contained  in 
plants.  I  do  not  however  deny  that  the  combuftion  of  a 
plant  may  not  give  rife  to  fome  of  them,  and  increafe  or  dimin- 
ifti  the  proportions  of  others.     Combuftion  miifl:  form  combina- 


Ait  of  Dying.  475 

tions  which  did  ftot  exid  in  the  plant,  and  deftroy  feveral  of 
thofe  whfch  exiftcd  before.  The  atmofpherick  air  employed  in 
this  operation  mud  unite  with  certain  principles,  and  produce 
various  refults.  The  nitrogene  gas  which  is  precipicMed  in  tor- 
rents in  the  focus  of  combuflion,  probably  combines  with  fome 
of  the  principles  ta  form  alkalis,  and  confequently  may  aug- 
ment the  quantity  of  thofe  which  naturally  cxift  in  the  plant. 


ARTICLE     XL 

Concerning  the  Colouring  Principles. 

The  object  of  the  art  of  dying  confifts  in  depriving  one  body 
of  its  colouring  principle,  to  fix  it  upon  another  in  a  durable 
manner  ;  and  the  feries  of  manipulations  neceflary  to  produce 
this  effe£l,  conftitutes  the  art  itfelf.  This  art  is  one  of  the  moft 
ufeful  and  wonderful  of  any  we  are  acquainted  with  ;  and  if 
there  be  any  one  of  the  arts  which  is  capable  of  infpiring  a  no- 
ble pride,  it  is  this.  It  not  only  affords  the  means  of  imitating 
nature  in  the  riches  and  brilliancy  of  her  colours  5  but  it  ap- 
pears to  have  furpaffed  her  in  giving  a  greater  degree  of  brillian- 
cy, fixity,  and  foiidity  to  the  fugacious  and  tranfient  colours 
with  which  {he  has  clothed  the  produtlions  around  us. 

The  feries  of  operations  whii^h  conftitute  the  art  of  dying, 
are  abfolutely  dependent  on  the  principles  of  chemillry  ;  and 
though  it  is  to  accidents,  or  the  very  (light  combination  of  fadls 
fuggefted  by  the  comparison  of  a  few  circumftances,  that  we 
are  indebted  in  this  part  of  chemiftry  for  feveral  excellent  re- 
ceipts, and  forae  principles ;  yet  it  is  not  the  lefs  true,  that  no 
confiderable  progrefs  will  ever  be  made,  nor  any  folid  foundation 
eftablifhed,  but  by  analyfing  the  operations,  and  reducing  them 
to  general  principles  ;  which  chemiftry  alone  can  afford.  The 
.jieceflity  of  eftabliffiing  proper,  principles  is  ftill  farther  e- 
vinced  by  the  uncertainty  and  continual  trials  which  prevail  in 
the  manufaftories.  The  flightcil  change  in  the  nature  of  the 
fubftances  puts  the  artift  to  a  ftand,  infomuch  that  he  is  incapa- 
ble of  himfelf  of  remedying  the  defects  which  arife.  Whence 
follow  continual  loffes,  and  a  difcouraging  alteration  of  fuccefs 
and  difappointmenr. 

The  little  progrefs  which  chemiftry  has  hitherto  made  in  the 
art  of  dying,  depends  on  feveral  caufes,  which  we  fhall  proceed 
to  explain. 

The  firft  caufe  of  this  flow  progrefs  depends  on  the  difHculty 
of  afcertaining  with  any  degree  of  certainty  the  nature,  proper- 


47^  ^fi  of  Dfing. 

tics,  and  affinities,  of  the  colouring  principle.  In  order  to  ex- 
tract this  principle,  we  muft  be  acquainted  with  the'  nature  of 
its  foivent ;  we  muft  know  whether  the  principle  be  in  a  Hate  of 
purity,  or  mixed  with  other  parts  of  the  vegetable  :  whether 
this  colouring  matter  confift  of  one  principle  alone,  or  is  formed 
by  the  union  of  a  number  :  we  muft  alfo  render  ourfelves  ac- 
quainted with  its  affinities  with  various  kinds  of  ftuff;  for  it  is 
afcertained  by  experience  that  certain  colours  adhere  very  well 
to  wool,  though  they  do  not  alter  the  whitenefs  of  cotton.  In 
addition  to  thefe  neceffiiry  parts  of  knowledge,  it  will  likewife 
be  required  to  determine  its  affinity  with  the  mordant,  for  alum 
is  the  mordant  for  fomc  colours  and  not  others  :  befides  which, 
the  adiion  or  efFetft  of  other  bodies  upon  the  colour  when  dyed 
muft  be  afcertained,  in  order  to  contrive  the  means  of  defend- 
ing it  from  alteration,  &c. 

The  fecond  caufe  which  has  retarded  the  application  of  chem- 
iiiry  to  dying,  is  the  difficulty  the  chemift  finds  in  procuring 
opportunities  of  making  experiments  in  the  large  way.  Preju- 
dice, which  reigns  defpotically  in  the  dye-houfe,  tends  to  expel 
the  chemift  as  a  dangerous  innovator  ;  and  the  proverb,  that 
Experience  is  better  than  Science^  contributes  to  prevent  the  in- 
trodu6bion  of  improvements  into  manufactories.  It  is  very  cer- 
tain that  a  dyer,  confined  to  the  mere  practical  part  of  his  bufi- 
nefs,  will  without  controverfy  produce  a  better  fcarlet  than  2, 
chemift  who  is  acquainted  only  with  the  principles  ;  for  the 
fame  reafon  as  a  fimple  workman  in  clock-making  will  make  a 
better  watch  than  the  moft  celebrated  rnechanick.  In  thefe  ca- 
fes we  may  admit  that  experience  is  better  than  fcience  ;  but 
when  it  is  required  to  refolve  any  problem,  to  explain  any  phcr 
nomenon,  or  to  difcover  fome  errour  in  the  complicated  details 
of  an  operation,  the  mere  artizan  is  at  the  end  of  his  knowledge, 
is  totally  at  alofs,  and  v/oiild  derive  the  greateft  advantage  from 
the  affiftance  of  the  man  of  fcience. 

Another  caufe  of  the  flow  progrefs  of  chemiftry  in  the  art  of 
dying,  is,  that  moft  of  the  v/orks  which  treat  upon  this  art  arc 
confined  to  defcriptions  of  the  procefles  ufed  in  the  manufaftc- 
ries.  Thefe  v/orks,  it  muft  be  admitted,  poflefs  their  advanta- 
fres ;  but  they  do  not  advance  the  fcience  of  operations  a  finglc 
ilep.  They  only  exhibit  the  fketch  of  a  country,  without  indi- 
cating either  its  relative  iituation,  or  the  nature  of  its  products. 
It  has  indeed  been  very  difficult,  till  lately,  to  do  more  than  this  ; 
becaufe  the  gafes,  v/hich  are  fo  greatly  concerned  in  this  pari: 
of  chemiftry  were  unknown  ;  becaufe  the  action  of  light  and 
of  the  air,  which  is  fo  powerful  upon  colours,  was  a  fa<ft  of 
which  neither  the  caufe  nor  the  theory  could  be  known  ;    and 


Art  of  Dying,  •■  477 

more  particularly  becaufe  the  falts  and  combinations  of  thirc, 
four  and  five  principles  were  not  known,  though  they  rery 
much  tend  to  render  the  efFeds  of  operations  on  vegetables 
more  complicated. 

In  order  therefore  to  make  a  progrefs  in  the  art  of  dying,  "Wc 
muft  ground  our  reafoning  on  otlier  principles.  I  (hall  proceed 
to  Iketch  out  a  plan  which  feems  to  me  to  be  adapted  to  this 
purpofe.     We  fhall  examine — 

1.  The  manner  in  which  the  colours  of  various  bodies  are  de- 
veloped and  formed. 

2.  The  nature  of  the  combinations  of  thefe  fame  colours  in 
thefe  bodies,  and  the  propereft  means  of  extrafting  them. 

3.  The  moft  advantageous  proceiTes  for  applying  them. 

I .  Colours  are  all  formed  in  the  folar  light.  The  property 
which  bodies  pofTefs  of  abforbing  fome  rays,  and  reflecting  oth- 
ers, forms  the  various  tinges  of  colours  with  which  they  are  dec- 
orated, as  is  proved  from  the  experiments  of  Newton. 

From  this  principle  we  may  confider  the  art  of  dying  under 
two  very  different  points  of  view.  For  we  may  determine  the 
colour  upon  a  body  either  by  changing  the  form  and  difpofition 
of  its  pores  ;  fo  that  it  may  acquire  the  property  of  refleding  a 
different  kind  of  rays  from  thoTe  which  it  reflected  before  it 
was  fubjc6led  to  thele  mechanical  operations.  Thus  it  is  that 
by  trituration  we  change  the  colour  of  many  bodies  ;  and  to 
this  caufe  it  is  that  we  muil:  refer  all  the  effeds  dependent  on 
the  reflexibility  and  refrangibility  of  rays.  This  coloration  de- 
pends, as  we  fee,  merely  on  the  changes  produced  in  the  furfa- 
cesof  bodies,  or  the  diipofition  of  their  pores.  The  phenome- 
na of  refrangibility  depend  on  the  denfity  or  fpecifick  gravity  of 
bodies,  according  to  Newton  and  Delaval. 

The  other  method  of  caufing  a  body  to  exhibit  a  determinate 
colour,  con  fids  in  transferring  to  the  furface  of  the  body  fome 
other  body  or  fubflance  which  poffeffes  the  property  of  reflecting 
this  known  ray.     This  is  the  effe£l  chiefly  produced  by  dying. 

But  in  what  manner  do  the  coloured  bodies  of  the  three  king- 
doms of  nature  acquire  the  property  of  conftantly  reflecting 
one  determinate  kind  of  rays  ?  This  is  a  very  delicate  queftion  j 
for  the  elucidation  of  which  I  Ihall  bring  together  a  few  fads. 

It  appears  that  the  three  colours  which  are  the  mofl:  eminently 
primiti^  in  the  arts  ;  thefe  whicli  form  all  the  others  by  their 
combination,  and  confequenrly  the  only  colours  to  which  we 
need  pay  attention;  that  is  to  fay,  ihc  blue,  the  vellow,  and 
the  red — are  developed  in  the  bodies  of  the  three  kingdoms  by 
.a  greater  or  lefs  abforption  of  oxigenr-,  vvkich  combines  with  tlie 
various  principles  of  thofe  bodies. 


47*  ^^t  of  Dying. 

In  the  mineral  kingdom,  the  firft  impreflion  of  fire,  6r  fhe 
firft  degree  of  caJciiiation,  developes  a  blue  colour,  fometimes 
interfperfed  with  yellow,  as  is  obfervable  when  lead,  tin,  copper, 
iron  or  other  metals,  areexpofed  in  a  ftate  of  fufion  to  the  ac- 
tion of  the  air,  to  haften  their  cooling.  This  may  be  efpecially 
©bferved  in  fteel  plates  which  are  coloured  blue  by  heating. 

Metals  acquire  the  property  of  reflecting  the  yellow  colour  by 
combining  with  a  greater  quantity  of  oxigene  ;  and  according- 
ly we  perceive  this  colour  in  moft  of  them,  in  |)ropoftion  as  the 
calcination  advances.  Mafficot,  litharge,  ochre,  orpiment,  and 
yellow  precipitate,  are  inftances  of  this. 

A  ftronger  combination  of  oxigene  appears  to  produce  the 
red  ;  whence  we  obtain  minium,  colcothar,  red  precipitate,  &c, 

This  procefs  is  not  uniform  through  all  the  bodies  of  the  min- 
eral kingdom  j  for  it  is  natural  to  infer  that  the  effects  muft  be 
modified  by  the  nature  of  the  bafe  with  which  the  oxigene  com- 
bines. Thus  it  is  that  in  fome  of  them  we  perceive  the  blue 
colour  almofl  immediately  followed  by  a  black  ;  as  tnay  eafily 
be  accounted  for,  on  the  conhderation  that  there  is  a  very  flight 
difference  between  the  property  of  refle<ri:ing  the  weakeft  rays 
and  that  of  refle£ting  none  at  all. 

To  give  additional  force  to  the  obfervarions  here  made,  we 
may  alfo  take  notice  that  the  metals  themfelves  are  moll  of  thehi 
colourlefs,  and  become  coloured  by  calcination  ;  that  is  to  fay, 
by  the  fixation  and  combination  of  oxigene. 

The  efFedlsof  the  combination  of  oxigene  ar$  equally  evi^ient 
in  the  mineral  as  in  the  vegetable  kingdom  ;  and,  in  order  to 
convince  ourfelvcs  of  thisj  we  need  only  follow  the  operations  in 
the  method  of  preparing  and  developing  the  principal  blue  col- 
ours, fuch  as  indigo,  paftel,  turnfole,  &c. 

Indigo  is  extracted  from  a  plant  known  by  the  name  of  Anil- 
lo  by  the  Spaniards,  and  the  Indigo  plant  by  us.  It  is  the  Idifjg- 
afera  tinBoria  of  Linnatis.  It  is  cultivated  at  Saint  Domingo, 
in  the  Antilles,  and  in  the  Eaft  Indies.  The  boughs  are  cut  ev- 
ery two  months,  and  the  root  lafts  two  years.  The  plant  is  laid 
to  ferment  in  a  trough  called  the  Iteeping  trough,  which  is  fil- 
led with  water.  At  the  end  of  a  certain  time  the  water  heats, 
emits  bubbles,  and  becomes  of  a  blue  colour.  It  is  then  pafled 
into  another  vefTel  or  trough,  called  the  beating  trough  (batterie), 
where  the  fluid  is  flrongly  beaten  or  agitated  by  a  mill  with  pal- 
lets, to  condenfe  the  fuWtance  of  the  indigo.  As  foon  as  the 
water  is  become  infipid,  it  is  drawn  off ;  and  the  depofition  of 
the  fecula  is  made  in  a  third  vefTel,  called  the  fettling  trough 
(repofoir),  where  it  dries,  and  is  taken  out  to  form  the  loaves 
diflributed  in  commerce. 


Art  of  Dying.  ^  479 

The  padel  is  a  colour  which  is  extracted  in  upper  Languedoc 
by  fermenting  the  leaves  of  the  plant  after  having  firfl:  bruifed 
them.  The  fermentation  is  promoted  by  moiftcning  them  with 
tlie  moft  putrid  water  that  can  be  procured. 

The  woad  is  prepared  in  Normandy  in  the  fame  manner  as 
the  paftel. 

Turpfole  is  prepared  in  Grand  Galargues  by  forking  rags  i» 
the  juice  of  the  croton  tin£lorium,  and  afterwards  expofmg  them 
to  the  vapour  of  urine  or  dung. 

Wc  likewife  obferve  that  the  firft  degree  of  combination  of 
o^igene  with  oil  (in  combuftion)  developes  the  blue  colour  for 
the  iridant. 

The  blue  colour  is  formed  in  dead  vegetables  only  by  ferment 
tation.  Now  in  thefe  cafes  there  is  a  fixation  of  oxigene.  This 
oxigene  combines  with  the  fecula  in  indigo,  with  an  extra£livc 
principle  in  turnfble,  &c  ;  and  moft  colours  are  likewife  fufcep- 
tible  of  being  converted  into  red  by  a  greater  quantity  of  oxi- 
gene. Thus  it  is  that  turnfole  reddens  by  expofure  to  air, 
or  to  the  adlion  of  acids  :  becaufe  the  acid  is  decompofed  upoa 
the  mucilage,  which  is  the  receptacle  of  the  colour  j  as  may  be 
feen  in  fyrup  of  vialets,  upon  which  the  acids  are  decempo-* 
fed  when  concentrated.  The  fame  thing  does  not  happen  whea 
a  fecula  is  faturated  with  oxigene,  and  does  not  admit  of  the 
decompofition  of  the  acid.  Hence  it  is  that  indigo  does  not  be- 
come red  by  acids,  but  is  on  the  contrary  foluble  in  them.  It 
is  likewife  for  the  fame  reafon  that  we  obferve  a  red  colour  de- 
veloped in  vegetables  in  which  an  acid  continually  aOs,  as  in 
the  leaves  of  the  oxahs,  of  the  virgin  vine,  the  common  forrel, 
and  the  ordinary  vine.  Hence  alfo  it  happens  that  acids  bright- 
en moft  of  the  red  colours  ;  and  that  a  very  highly  charged 
metallick  oxide  is  ufed  as  the  mordant  for  fcarlet. 

We  find  the  fame  colours  developed  in  the  animal  kingdom 
by  the  combination  of  the  fame  principle.  When  flefh-meat 
putrefies,  the  firft  impreflion  of  the  oxigene  confifts  in  proilu- 
cing  a  blue  colour  ;  whence  the  bhie  appearance  of  mortifica- 
tions, of  flefii  becoming  putrid,  of  game  too  long  kept,  or  the 
appearance  which  in  our  kitchens  in  France  is  called  cgrdon  hieu^ 
This  blue  colour  is  fucceeded,  by  red,  as  is  obferved  in  the  pre- 
paration of  cheefes,  which  become  covered  with  a  mouldinef* 
at  firft  of  a  blue  colour,  but  afterwards  becoming  red  :  I  have 
purfucd  thefe  phenomena  in  the  preparation  of  the  cheefes  at 
Rocquefort.  The  combination  of  oxigene,  and  the  proportion- 
al quantity  which  enters  into  fuch  combination,  determine  there-, 
fore  the  property  of  reilecling  any  particular  rays  of  fight.  But 
it  may  eafily  be  underftood  that  the  colour  muft  be  fubjccl   to 


4S0  ^  Kaiiit'-e  of  Coloun, 

variation  according  to  the  nature  of  the  principle  with  which  it 
combines  ;  and  this  points  out  a  feries  of  very  interefling  ex- 
periments that  remain  to  be  made. 

Ail  the  phenomena  of  the  combination  of  air  with  the  feveral 
principles  in  different  proportions  may  be  obferved  in  the  flame 
of  bodies  acluaiiy  on  fire.  This  flame  is  blue  when  the  com- 
bnftion  is  flow  ;  red,  when  ftronger  and  more  complete  ;  and 
white,  when  ftill  more  perfect.  For  thefe  final  degrees  of  oxi- 
dation in  general  produce  a  white  colour,  becaufe  all  the  rays 
arc  then  equally  reflected. 

From  the  foregoing  fa(5ls  we  may  conclude  that  the  blue  ray 
is  the  weakefl:,and  isconfequently  rcflecfled  by  the  firft  combina- 
tion of  oxigene.  We  may  add  the  following  fadl  to  thofe  we 
have  already  exhibited.  The  colour  of  the  atmofphere  isbluifli; 
the  light  of  the  liars  is  blue,  as  M.  Mariotte  has  proved,  in  the 
year  1678,  by  receiving  the  light  of  the  moon  upon  white  pa- 
per :  the  light  of  a  clear  day  reflected  into  the  fliade  by  fnow, 
is  of  a  fine  blue,  according  to  the  obfervations  of  Daniel  Major, 
(Ephem.  des  Curiof.  de  la  Nature,  167 1,  premier  Dec.) 

The  colouring  principle  is  fouad  in  vegetables  in  four  ftates 
of  combination — i.  "V^^th  the  extractive  principle.  2.  With 
the  re fi nous  principle.  3.  With  a  fccula.  4.  With  a  gummy 
principle. — Thefe  four  Hates  in  which  we  lind  the  colouring 
principle,  indicate  to  us  the  means  of  extradling  it. 

A.  When  the  receptacle  of  the  colour  is  of  the  nature  of  ex- 
tra£ls,  water  is  capable  of  diflblving  the  whole  :  fuch  is  that  of 
logwood,  turnfole,  madder,  cochinille,  he.  Nothing  more  is  ne- 
ceflliry  than  to  infufe  thefe  fahflances  in  water,  for  the  purpofe 
of  extracting  their  colouring  principle.  If  any  ftufl^be  plunged 
in  this  folution,  it  will  be  covered  with  a  body  of  colour,  which 
will  be  a  mere  ftain,  that  may  be  again  cleared  ofi^  by  water.  To 
obviate  this  inconvenience,  it  has -therefore  been  found  necefla- 
ry  to  impregnate  the  ilufl^s  on  v/hich  rhe  colours  were  intended 
to  be  applied  with  fome  fait  Or  other  principle,  which  might 
change  the  nature  of  the  qolouriiig  ^natter,  and  give  it  fixity,  by 
depriving  it  of  its  folubility  in  water  .it  is  this  fubftance  which 
is  -diiiinguifhed  by  the  name  of  Mordant.  It  is  like  wife  neccf- 
fary  that  the  mordant  fliouid  have  an  affinity  vvith  the  principle 
of  colour  •,  in  order  that  it  may  become  its  receiver.  Hence 
it  arifes  that  mofl  of  tliefe  colours,  fuch  as  turnfole,  Brazil 
wood,  &c.  are  not  fixed  by  rheie  mordants  ;  hence  it  alfo  arifes 
that  cochinille  does  not  form  a  fine  fcarict,  unlefs  it  has  tin  for 
its  mordant.  It  is  neci^iTary,  moreover,  that  the  mordant  have 
due  relation  to  the  nature  of  the  (tuff  ;  for  the  fame  compofi- 
tion  which  gives  a  fine  fcarlet  colour  to  wool,  gives  a  colour  of 


Art  of   Dying.  48 1 

^ine  lees  to  filk,  and  does  not  even  change  the  white  colour  of 
cotton. 

B.  There  are  certain  refinous  colouring  matters  foluble  in  fplr- 
it  of  wine:  fuch  are  the  pharmaceutical  tinclures  :  they  are 
ufed  only  in  the  arts  for  dying  ribbons.  »Tliere  are  other  col- 
ouring matters  combined  with  feculge,  which  water  does  not  dif- 
folvc  :  rocoUj  archii,  indigo,  and  the  red  colour  of  oriental  faf- 
fron,  are  of  this  kind. 

Rocou  is  a  refinous  fecula  obtained  by  macerating  the  feeds 
of  an  American  tree  called  tlrucu  in  water.  In  this  operation 
the  extractive  part  is  deflroyed  by  fermentation,  and  the  refinous 
fecula  is  collecfled  in  a  pafte  of  a  deep  yellow  colour.  The  pafte 
of  rocoii,  diffufed  in  water  with  the  impure  alkali  called  cendres 
gravilees,  affbrds  a  fine  orange  colour. 

Archil  is  a  pafte  prepared  by  macerating  certain  mofTes  and 
lichens  in  urine  with  lime.  Alkalis  extra<5l  a  violet  colour. 
Archil  is  made  in  Corfica,  in  Auvergne,  at  Lyons,  &c. 

The  Archil  of  the  Canaries  is  lefs  charged  with  lime.  That 
which  I  procured,  exhibited  in  its  texture  the  fibres  of  the  plant, 
not  completely  decompofed  by  the  fermentation.  The  archil  of 
the  Canaries,  or  the  archil  in  the  herb,  is  afforded  by  a  lichen 
called,  Orcella)  rocella,  lichen  frutlculofusy  folidus ^  aphylluSy  fubra- 
mojusy  tuherculis  altermsy  hinn^i.  The  parella  or  archil  of  Au- 
vergne is  made  with  the  lichen  parellus  Linnxi. 

The  colouring  matters  of  this  clafs  are  ail  foluble  in  alkali  or 
lime  ♦,  and  thefe  are  the  fubftances  ufed  to  diffolve  them  in  v/a- 
ter,  and  precipitate  them  upon  ftufi^s.  Lime  is  the  true  folvent 
of  indigo  ;  but  alkali  is  the  folvent  of  other  fubftances  of  the 
fame  clafs.  For  example  :  when  it  is  required  to  make  ufe  of 
the  colouring  matter  of  baftai-d  faffron,  the  firft  proceeding  con- 
fifts  in  wafiiing  it  in  much  water,  to  clear  it  of  the  extractive 
and  yellowifli  principle,  which  is  very  abundant ;  and  the  refin- 
ous principle  is  afterwards  dlffolved  by  means  of  alkali,  from 
which  folvent  it  is  precipitated  upon  the  ftuffs  by  means  of  acids. 
In  this  manner  it  is  that  tiie  poppy-coloured  filk  is  made.  This 
refinous  principle  may  alfo  be  combined  with  talc,  after  it  has 
been  extraded  by  an  alkali,  and  precipitated  by  an  acid ;  in 
which  cafe  the  ifefult  is  vegetable  red.  To  make  this  pigment, 
the  yellow  colour  of  faffron  or  carthamus  is  firft  extracted  by 
means  of  wafiiing.  Five  or  fix  per  cent,  of  i;s  weight  of  {o^i, 
is  mixed  with  the  refidue  ;  and  cold  water  poured  on,  which 
tikes  up  a  yellow  matter  5  and  this,  by  the  addition  of  lemon 
juice,  depolitcs  a  red  fecula.  The  red  fecula,  mixed  with  levi- 
gated talc,  and  moiftened  with  lemon  juice,  forms  a  pafte, 
which  is  put  into  pots  to  dry.  If  the  red  be  foluble  in  fpirit  of 
3...N 


ts 


4S2  Art    of   Dymg, 

wine,  it  is  vegetable  j  but  if  not  it  is  mineral,  and  is  ufually  ver- 

million. 

Acids  may  be  ufed  inllead  of  alkalis  in  fixing  fome  of  thefc 
colours  upon  (luffs.  To  make  a  permanent  blue,  inftead  of  dif- 
folving  indigo  by  means  of  lime,  it  is  fometimes  diifolved  in  oil 
of  vitriol.  This  folution  is  poured  into  the  bath,  and  the  alum- 
cd  ftuff  is  pafied  through  it.  Flannels  are  died  blue  at  Mont- 
pellier  in  this  way.  This  operation  depends  merely  on  an  ex- 
treme divifion  of  the  indigo  by  the  acid. 

D.  There  are  fome  colouring  principles  fixed  by  refin  ;  but 
which,  by  the  afTiilance  of  extra£l:ive  matter,  may  be  fufpended 
by  water.  The  fluffs  are  boiled  in  this  folution  ;  the  refmous 
part  applies  itfelf  to  them,  and  adheres  with  fufhcient  folidity  not 
to  be  again  carried  off  by  water. 

No  preparation  is  required  to  dye  with  thefe  ingredients, 
nothing  more  being  neceffary  than  to  boil  the  fluff'  in  a  decoc- 
tion of  the  colour.  The  principal  fubitances  of  this  kind  are, 
the  huflc  of  walnuts,  the  roots  of  the  walnut  tree,  fumach,  fan- 
tal,  the  bark  of  eld^r,  &c.  All  thefe  fubftances,  which  require 
no  mordants,  afford  only  a  buff-coloured  tinge,  which  dyers  call 
Root  Colours.  The  colouring  matter  of  certain  vegetables  may 
likewife  be  extracted  by  oils.  In  this  way  oils  are'coloured  red 
by  infufmg  alkanet,  or  the  root  of  a  certain  fpecies  of  buglof* 
in  them. 

In  order  to  apply  colouring  matter  properly  upon  any  ftuff,  it 
is  neceffary  to  prepare  the  fluff,  and  difpofe  it  to  receive  the 
colouring  principle^  For  this  purpofe  it  muff  be  waflied, 
bleached,  and  cleared  of  that  glutinous  matter  which  defends  it 
from  the  deftru£live  aclion  of  the  air  while  it  grows  on  the  ani- 
mal which  affords  it ;  and  impregnated  with  the  mordant  which 
fixes  the  colour,  and  gives  it  peculiar  properties. 

A.  Tl)e  firfl:  operation  required  to  difpofe  a  ftuff  to  receive 
colour,  is  bleaching  ;  becaufe  the  whiter  it  is,  the  more  natural 
and  accurate  will  be  the  colour  it  takes.  If  this  precaution  be 
not  taken,  the  fucccfs  vvill  be  uncertain.  To  bleach  piece  goods, 
the  operator  is  fatisfied  with  boiling  them  in  an  alkaline  lixivium, 
and  expofing  them  afterwards  to  the  air,  to  render  the  white- 
nefs  more  perfect.  This  operation  depends  on  thea£lion  of  the 
oxigene,  which  combines  with  the  colouring  principle,  and  de- 
ftroys  it;  as  is  e\ndently  demonftrated  by  the  late  experiments 
of  M.  Berthollet  on  the  oxigenated  muriatick  acid,  which  bleach- 
es cloths  and  cottons  with  fuch  facility,  that  it  is  already  ufed 
for  this  purpofe  in  feveral  manufa£lories. 

Cotton  is  bleached  in  fome  manufa«5lories  by  a  very  ingenious 
IJTGcefs.     A  boiler  is  firmly  fet  in  mafonry,  and  a  cover  fitted  la 


..-^ 


Art    of  Dying,  483 

it  in  the  flrongeft  manner  ;  this  boiler  has  an  elliptical  figure. 
Alka'i  rendered  cauftick  by  lime  is  put  into  the  bottom  of  this 
veflel  5  and  the  goods  intended  to  be  bleached  are  put  into  a 
bafket  which  prevents  their  touching  the  fides  of  the  boiler. 
When  the  piece-goods  are  properly  placed,  the  covering  is  fixed 
on,  which  is  pierced  by  a  very  fmall  aperture,  to  permit  a  por- 
tion of  the  aqueous  vapour  to  efcapc.  A  degree  of  heat  much 
fuperiour  to  that  of  boiling  water  is  excited  in  the  folution  of 
pot-afli :  and  the  heat,  afliited  by  the  corrofive  adion  of  the  pot- 
afli  in  this  kind  of  Papin*s  digelter,  deftroys  the  colouring  prin- 
ciple of  the  cottons,  and  gives  them  the  utmoft  whitenefs. 

B.  That  kind  of  gluten  which  envelopes  almoft  every  animal 
fubllance,  but  more  efpecially  raw  filk,  is  infoluble  in  water  and 
in  alcohol.  It  is  only  attacked  by  alkalis  and  foaps  ;  and  for 
this  purpofe  the  operation  of  cleanfing  is  ufed.  Any  fluff  may 
be  cleared  of  its  glutinous  part  by  boiling  or  even  digefling  it  in 
a  folution  of  alkali  ;  but  it  has  been  obierved  that  a  pure  alkali 
alters  the  goodnefs  and  quality  of  the  ftufF ;  for  which  reafon 
foaps  have  been  fubflituted  in  its  flead.  For  this  purpofe  the 
fluff  is  fleeped  in  a  folution  of  foap,  heated  to  a  lefs  degree  than 
boiling.  The  academy  of  Lyons,  in  the  year  1761,  ipropofed  a 
prize  for  the  means  of  clearing  raw  filks  without  foap.  It  was 
adjudged  to  M.  Rigaut,  of  St.  Quentin,  whopropofed  a  folution 
of  fait  of  foda. 

It  has  been  lately  afcertained  that  water,  heated  above  the  de- 
gree of  ebullition,  is  capable  of  difTolving  this  colouring  princi- 
ple. A  boiler  fimilar  to  that  I  have  juit  defcribed,  may  be  ufed 
for  this  purpofe. 

In  order  to  bleach  cotton,  and  difpofe  it  for  the  dying  pro- 
ceffes,  it  is  is  cleanfed  by  means  of  a  liquid  foap  made  of  oil  and 
foda. 

The  piece  goods  are  cleared  by  this  boiling  from  the  varnifh, 
which  would  prevent  the  colour  from  applying  and  fixing  itfelf 
in  a  permanent  manner  ;  at  the  fame  time  that  it  opens  the 
pores  of  the  fluff  for  the  better  reception  of  the  colour. 

When  the  piece  is  thus  prepared,  its  pores  being  very  open, 
and  its  colour  very  white,  nothing  remains  to  be  done  previous 
to  the  application  of  the  dye,  but  to  impregnate  it  with  the 
mordant  or  principle  which  is  to  receive  the  colour  and  change 
its  nature  fo  much,  that  neither  water,  foap,  nor  any  of  the  re- 
agents ufed  as  proofs,  may  be  capable  of  extra6ling  it.  It  is  ne- 
ceffary  therefore — i.  That  the  mordant  itfelf  Oiould  be  very 
white,  that  it  may  not  alter  the  colour  prefented  to  it.  2.  That 
t  be  not  fubjecl  to  corruption  ;  and  for  this  purpofe  it  mud  be 
ought  among  the  earths  and  metallic k  oxidea.     3.  That  it  be 


4S4  Toll  en  of  Vegetables. 

in  date  of  extreme  divifion,  in  order  that  it  may  fix  itfcif  i« 
the  pores.  4.  That  it  be  infoluble  in  water  and  the  other 
reagents.  5.  That  its  afhnity  with  the  colouring  matter  and 
the  ftufF  be  vevy  great. 

Alum  and  the  muriate  of  tin,  are  the  two  falts  whofe  bafe^ 
unite  thefe  properties  in  the  mod  efficacious  manner.  The  fluffs 
having  undergone  the  previous  operations  are  therefore  fleeped 
in  folutions  of  thefe  falts  j  and  when  they  are  impregnated,  they 
are  pafTed  through  the  colouring  bath  :  and  by  the  decompofi- 
tion,5or  change  of  principles  between  the  mordant  and  the  prin- 
ciple which  holds  the  colour  in  folution,  the  colour  is  precipi- 
tated on  the  bafe  of  the  mordant,  and  adheres  to  it. 

Certain  vegetable  fubflances  are  likev/ife  difpofed  to  take  fomc 
coulours  by  animalizing  them  In  this  way  cows'  dung  and  bul- 
lock's blood  are  ufed  in  dying  cotton  ;  for  it  is  a  decided  fadl; 
that  animal  fubftances  tal^e  colours  better  than  vegetables. 


ARTICLE    XII. 

Concerning  the  Pollen  or  Fecundating  Powder  of  the  Stamina  of  Vegeta?. 

bles. 

Modern  difcoveries  and  obfervarions  have  pointed  out  the  fex- 
ual  parts  of  plants  ;  and  we  find  nearly  the  fame  forms  in  the 
organs,  the  fame  means  in  the  functions,  and  the  fame  charac- 
ters in  the  prolifick  humours,  as  in  animals. 

The  proiifick  humour  in  the  male  part  is  elaborated  by  the 
Anther  a  :  and  as  the  organs  of  the  plants  do  not  admit  of  an  ac- 
tual intromifTion  of  the  male  into  the  female,  becaufe  vegetables 
are  not  capable  of  loco-motion,  nature  has  beflowed  on  the  fe- 
cundating feed  the  character  of  a  powder  5  which  the  agitation 
of  the  air,  and  other  caufe.s,  may  carry  away  and  precipitate 
upon  the  female.  There  is  a  degree  of  elaflicity  in  the  anthera, 
which  caufes  it  to  open,  and  eje£t  the  globules.  It  has  even 
been  obferved  that  the  piflil  opened  at  the  fame  time,  to  receive 
tiie  pollen,  in  certain  vegetables.  The  refources  of  nature  to 
affure  the  fecundation  are  admirable.  The  male  and  female 
parts  almoft  always  repofe  in  the  fame  flower  5  and  the  petals 
iire  always  difpofed  in  the  moft  advantageous  manner  to  favour 
the  reprcduftion  of  the  fpecies.  Sometimes  the  male  and  fe- 
male upon  the  famx  individual,  but  placed  upon  different  flow- 
ers ;  at  other  times  both  are  attached  to  ifolated  and  feparate 
individuals,  and  then  the  fecundation  is  made  by  the  pollen 
which  the  wind  or  air  detaches  from  the  anthera,  and  tranfmit^ 
IP  the  fpmale. 


^Formation  of  Wax,  48  <j 

The  fecundating  powder  has  almoft  conftantly  the  fmell  of 
the  fpermatick  liquor  of  animals.  The  fmeii  of  cabbages  in 
blofTom,  of  the  chefnut  tree,  and  moll  other  vegetables,  exhibits 
this  analogy  to  fuch  a  degree,  that  the  one  odour  might  even  be 
miftaken  for  the  other. 

The  pollen  is  generally  of  a  refinous  nature,  foluble  in  alka- 
lis and  in  alcohol.  Like  refms,  it  is  inflammable  ;  and  the  aura 
which  is  formed  around  certain  vegetables  at  the  time  of  fecun- 
dation, may  be  fet  on  fire,  as  was  obferved  by  Mademoifelle  Lin- 
ne  in  the  fraxinella. 

Nature,  which  has  employed  lefs  economical  means  in  the 
fecundation  of  plants,  and  who  entrufts  thefe  operations  almoft 
to  chance,5rmce  (lie  delivers  the  fecundating  powder  to  the  winds 
muft  of  courfe  have  been  prodigal  in  the  formation  of  this  hu- 
mour, more  efpecially  for  the  trees  of  the  monoecia  and  dioecia 
genera,  where  the  production  is  more  e:;pofed  to  accidental  im- 
pediments. Hence  we  may  account  for  thofe  pretended  (bow- 
ers of  fulphur,  which  are  never  common  but  in  fuch  diftrids  as 
abound  with  the  hazel,  filbert,  and  pine-trees. 

As  the  pollen  could  not  be  expofed  by  nature  to  the  varying 
temperatures  of  the  atmofphere,  fhe  has  facilitated  its  develope- 
ment  in  the  mod  rapid  manner.  A  warm  fun  very  frequently 
fuffices  to  open  the  concealed  organs  of  the  plant,  to  developc 
and  procure  its  fecundation.  On  this  account  the  author  of  Les 
£tudes  de  la  Nature  affirms,  that  the  coloration  of  plants  is  de- 
figned  to  reflect  the  light  more  vividly,  and  that  moft  flowers 
afTeft  the  moft  advantageous  form  to  concentrate  the  folar  rays 
on  the  parts  of  generation. 

The  parts  employed  in  thefe  functions  are  endued  with  an  af- 
tonifhing  degree  of  irritability.  M.  des  Fontaines  has  made 
Ibme  very  intereiling  obfervations  on  this  fubjeCl ;  and  the  agi- 
tated motions  v/hich  fome  plants  affect  in  order  to  follow  the 
courfe  of  the  fun,  are  determined  by  nature,  in  order  that  the 
great  work  of  generation,  favoured  by  the  fun,  may  be  accom* 
pliflied  in  the  leaft  poflible  time. 

Concerning  Wax. 
The  wax  of  bees  is    merely   the  pollen  very   little   altered, 
Thefe  Infects  have  th^ir  femurs  provided  with  rugofities  to  brufli 
the  pollen  from  the  antherje,  and  convey  it  to  their  nefts. 

There  appears  to  exill  in  the  very  texture  of  fome  flowers, 
which  are  rich  in  fecundating  powder,  a  matter  analogous  to  wax 
which  may  be  extra£ted  by  aqueous  decoction.  Such  are  the 
male  catkins  of  the  betula  alnus,  thofe  of  the  pine,  &c.  the 
Jeaves  of  rofemary,  of  oflicinal  fagc,  the  fruitb  of  the  mirica 
fjerifera,  fuifer  wax  to  tranfude  through  the  pores. 


4t6  Secntion  of  Honey, 

It  appears  that  wax  and  the  pollen  haye  for  their  ba/iS'  a  fat 
cil,  which  pafles  to  the  ftate  of  refin  by  its  combination  with 
oxigene.  If  the  nitrick  ormuriatick  acid  be  digefted  upon  fix- 
ed oil  for  feveral  months,  it  pafTes  to  a  ftate  refembling  wax. 

Wax,  by  repeated  diftillations,  affords  an  oil  which  pollefles 
all  the  properties  of  volatile  oils.  It  is  reduced  into  water  and 
carbonick  acid  by  combuftion. 

The  colouring  matter  of  wax  appears  to  be  of  the  fame  nature 
as  that  of  filk  ;  it  is  infoluble  in  water  and  in  alcohol.  In  the  arts, 
wax  is  bleached  by  dividing  it  prodigiouily  ;  for  which  purpofe 
oil  is  poured  in  fufion  upon  the  furface  of  a  cylinder,  which  re- 
Tolves  at  the  furface  of  water.  The  wax  \^hicli  fails  applies 
itfelf  to  the  fuperficies,  and  is  reduced  into  very  thin  flakes 
cr  ribbons.  It  is  afterv.'ards  expofed  to  the  air  upon  tables,  ta- 
king care  to  ftir  it  from  time  to  time,  and  by  this  means  it  be- 
comes white. 

Alkalis  difFolve  wax,  and  render  it  foluble  in  water.  It  is 
this  faponaceous  folution  which  forms  the  punick  wax.  It  may 
be  ufed  as  the  bafs  of  feveral  colours  v  and  may  be  made  into 
an  excellent  pafte  for  wafhing  the  hands.  It  is  likewife  applied 
with  a  bruili  upon  feveral  bodies  :  but  it  would  be  highly  ad- 
vantageous if  it  could  be  deprived  of  its  folvent,  which  conftant- 
ly  afts,  and  is  the  caufe  why  it  cannot  be  applied  to  feveral  ufes 
in  which  othcrwife  it  might  be  found  advantageous. 

Ammoniack  likewife  diflulves  it  ;  and  as  this  folvent  is  evap- 
©rable,  it  ought  to  be  preferred  when  it  is  propofed  to  ufs  the 
wax  as  a  varnifti. 


ARTICLE  XIII. 

Concerning  Honey. 

Honey,  or  the  ne£tar  of  flowers,  is  contained  chiefly  In  the 
We  of  the  piftil,  or  female  organ.  It  ferves  as  food  for  moft 
infe£ls  which  have  a  probofcis.  Thefe  animals  plunge  their 
probofcis  into  the  piftil,  and  fuck  out  the  nedar.  It  appears 
to  be  a  folution  of  fugar  in  mucilage  ;  the  fugar  is  fometime* 
precipitated  in  cryftals,  as  in  the  ne<Slar  of  the  flower  of  balfa- 
mina. 

The  nc£lar  undergoes  no  alteration  In  the  body  of  the  bee, 
fince  we  can  form  honey  by  concentrating  the  ne6lar.  It  re- 
tains the  odour,  and  not  unfrequently  the  noxious  qualities  of 
the  plant  which  aflFords  it. 

The  fecretion  of  the  neclar  is  made  during  the  feafon  of  fe- 
cundation.    It  may  be  confidcred  as  the  vehicle  and  recipient  of 


Properties  of  Woody  Matter,  ^^tj 

the  fecundating  dud,  which  facilitates  the  burfting  of  globules, 
filled  with  this  fecundating  powder :  for  Linnceus  and  Toume- 
fort  have  both  obferved  that  nothing  more  is  required  than  to 
cxpofc  the  pollen  upon  water,  to  affiii:  the  developement.  All 
the  internal  part  of  the  ftyle  of  the  piftil  is  impregnated  with  it. 
And  if  the  internal  part  of  the  female  organs  be  dried  by  heatf 
the  pollen  no  longer  fecundates. 

Honey  exudes  from  all  the  female  parts,  but  particularly  from 
the  ovaria.  Pores  may  even  be  obferved  in  hyacinths,  through 
which  it  flows,  Such  flowers  as  have  only  the  male  parts  do 
not  in  general  afford  honey  ;  and  the  organs  which  afford  the 
ne£tar  dry  up  and  wither  from  the  moment  the  a(£l  of  concep- 
tion ir.  accompliflied.  Honey  may  therefore  be  confidered  as 
neceflary  to  fecundation  ;  it  is  the  humour  afforded  by  the  fe- 
male to  receive  the  fecundating  powder,  and  facilitate  the  open- 
ing and  explollon  of  the  fmall  bodies  which  contain  the  pollen  ; 
for  it  has  been  obferved  that  thefe  bodies  open  the  moment  they 
touch  the  furface  of  any  liquid  which  moiftens  them. 


ARTICLE    XIV. 

Concerning  the  Ligneous  Part  of  Vegetables. 

Chemlds  have  conftantly  directed  their  attention  to  the  analy- 
(is  of  vegetable  juices  ;  but  they  appear  to  have  completely  neg- 
ledted  the  folid  part  of  the  vegetable,  which  in  every  point  of 
view  is  entitled  to  particular  attention.  It  is  this  ligneous  por- 
tion which  forms  the  vegetable  fibre  ;  and  this  matter  not  only 
conditutes  the  bafis  of  the  vegetable,  but  is  likcvife  developed 
in  circumltances  which  depend  on  the  vital  functions  of  the 
plant.  It  forms  the  pulp  of  feeds,  the  lanuginous  covering 
which  overfpreads  certain  plants,  &c.  The  chara<fler  of  the. 
ligneous  part  is,  an  infolubility  in  water  and  almofl:  every  other 
menftruum.  The  fulphurick  acid  only  blackens  it,  and  is  de- 
compofed  upon  it,  as  is  likewik  the  nitrick  acid.  But  one  very 
peculiar  chara6ter  of  this  principle  is,  that  the  concourfc  of  air 
and  water  alters  it  very  difficultly-  •,  and  tlrat,  when  it  is  well  de- 
prived of  all  its  moifture,  it  abfolutely  refifts  every  kind  of  fer- 
mentation ;  infomuch  that  it  would  be  inden.ru£l:ible,  if  infe«fbs 
had  not  the  property  of  gnawing  and  feeding  upon  it.  It  ap- 
pears that  the  vegetable  fibre  confifts  of  the  bafis  of  mucilage 
hardened  by  its  combination  with  a  greater  quantity  of  oxigene. 
Several  reafons  led  us  to  adopt  this  idea.  In  the  firft  place,  the 
tliluted  nitrick  acid  being  put  to  digeft  upon  fecnla  is  decompof- 
«d,  and  caufes  the  fccula  to  pafs  to  a  rfate  refemblinjj  that  of 


.  4^S  Fliied  Principles  of  Vegetables. 

ligneous  matter.  I  have  obferved,  in  the  fecond  place,  that  thofe 
fungi  which  grow  in  fubterraneous  places  void  of  light  and  are 
refolved  into  a  very  acid  water,  if  left  in  a  veflel,  acquire  a  great- 
er quantity  of  the  ligneous  principle,  in  proportion  as  they  are 
expofed  by  degrees  to  the  light ;  at  the  fame  time  that  the  acid 
is  diminifhed  by  decompofition,  and  at  length  difappears. 

The  tranfition  of  mucilage  to  the  ftate  of  ligneous  matter  is 
very  evident  in  the  growth  of  vegetables.  The  cellular  envelope 
which  is  immediately  covered  by  the  epidermis  exhibits  nothing 
but  mucilage  and  glands  ;  but  by  degrees  it  hardens,  forms  a 
flratum  of  the  cortical  coating,  and  at  laft  concludes  by  becom- 
ing one  of  the  ligneous  rings. 

We  obferve  this  tranfition  in  certain  plants  which  are  annual 
in  cold  climates,  and  vivacious  in  temperate  climates.  In  the 
former  they  are  herbaceous,  becauie  the  periodical  return  of  the 
cold  weather  does  not  permit  them  to  develope  themfelves. 
In  the  fecond  they  become  aborefcent ;  and  the  progrefs  of 
time  hardens  the  mucilage,  and  forms  ligneous  coatings. 

The  induration  of  the  fibrous  part  may  be  accelerated  by 
caufing  the  air  and  light  to  a6t  more  ftrongly  upon  it.  M.  dc 
BufFon  has  obferved  tnat,  when  a  tree  is  deprived  of  its  bark, 
the  external  part  of  the  wood  which  is  expofed  to  the  air,  ac- 
quires a  confiderable  degree  of  hardnefs  j  and  trees  thus  pre- 
pared form  pieces  of  carpentry  much  more  folid  than  thofe 
which  have  not  undergone  fuch  preparation. 

It  is  probably  owing  to  the  large  quantity  of  pure  air  with 
which  the  fibrous  matter  is  loaded,  that  it  is  not  difpofed  to  pu- 
trefy ;  and  it  is  in  confequence  of  this  moO:  valuable  property 
of  not  being  fabjecl  to  corruption,  that  arts  have  been  invented 
for  clearing  it  of  all  fermentable  principles  of  the  vegetable  king- 
dom, to  obtain  it  in  its  greateft  purity  in  the  fabrication  of 
cloths,  paper,  occ  We  fliall  again  return  to  thefe  objects, 
when  we  treat  of  the  alterations  to  which  the  vegetable  king- 
dom is  fubject. 

ARTICLE     XV. 

Concerriing  other  fixed  principles  of  tlie  Vegetable  Kingdorf?* 

The  volatile  oil  of  horfe-radifhhad  formerly  afforded  fulphur, 
which  is  depofited  bv  (landing,  according  to  the  obfervations  of 
fome  chemids  ;  hut'M.  Deyeux  has  taught  us  to  extra^:  this 
inflammable  principle  from  the  root  of  the  herb  patience.  ^  No- 
thing is  required  to  be  done  but  to  rafp  the  root,  boil,  take  off 
the  fcum,  and  dry  it.     This  fcum  affords  much  fulphur  in   fub- 


Fixed  Principles  of  Vegetables.  ^g^ 

ftancc  *,  and  it  is  perhaps  to  this  principle  thatthefe  plants  owe 
their  virtue,  fince  they  are  ufed  in  flcin  diforders. 

Vegetables  in  their  analyfis  likewife  prelent  us  with  certain 
metals,  fuch  as  iron,  gold,  and  manganefe.  The  iron  forms 
near  one  twelfth  of  the  weight  of  the  afhes  of  hard  wood,  fuch 
as  oak.  It  may  be  extracted  by  the  magnet.  It  does  not  ap- 
pear to  exid  in  a  perfedly  difengaged  (tate  in  the  vegetable  ; 
neverthelefs  we  read,  in  the  Journaux  de  Phyfique,  an  obferva- 
tion  in  which  it  is  atHrmed,  that  it  was  found  in  metallick  grains 
in  fruits.  The  iron  is  ufually  held  in  folution  in  the  acids  of 
vegetation,  from  which  it  may  be  precipitated  by  alkalis.  The 
exiftence  of  this  metal  has  been  attributed  to  the  wearing  of 
ploughfliares,  and  other  inflruments  of  hufbandry,  and  to  the 
faculty  which  plants  polTefs  of  imbibing  it  with  their  nutritive 
juices.  The  Abbe  Nolet  and  others  have  embraced  this  unphi- 
lofophical  notion.  It  is  the  fame  with  the  iron  as  with  the  other 
falts.  They  are  produced  by  vegetation  ;  and  vegetables  wa- 
tered with  diflilled  water  afford  it  as  well  as  others. 

Beccher  and  Kunckel  afcertained  the  prefence  of  gold  in 
plants.  M.  Sage  was  invited  to  repeat  the  proceiTes  by  way  of 
afcertaining  the  fa6l.  He  found  gold  in  the  allies  of  vine  twigs, 
and  announced  it  to  the  publick.  After  this  chemill,  moft  per- 
fons  who  have  attended  to  this  objeft  have  found  gold  ;  but 
in  much  lefs  quantity  than  M.  Sage  had  announced.  The 
moft  accurate  analyfes  have  fhown  no  more  than  two  grains  ; 
whereas  M.  Sage  had  fpoken  of  fcveral  ounces  in  the  quintal. 
The  procefs  for  extracting  gold  from  the  aflies  con  fids  in  fufing 
them  with  black  flux  and  minium.  The  lead  which  is  produ- 
ced is  then  cupelled,  to  afcertain  the  fmall  quantity  of  gold 
with  which  it  became  alloyed  in  this  operation. 

Scheele  has  alfo  obtained  manganefe  in  the  analyfis  of  vege- 
table afhes.  His  procefs  conlifts  in  fufing  part  of  the  afhes 
with  three  parts  of  fixed  alkali,  and  one  eighth  of  nitrate  of  pot- 
afli.  The  fufed  matter  is  boiled  in  a  certain  quantity  of  water. 
The  folution  being  then  filtered,  is  faturated  with  fulphurick  ac- 
id, and  at  the  end  of  a  certain  time  manganefe  fails  down. 

Lime  conftantly  enough  forms  kv^ii  tenths  of  the  fixed  refi- 
due  of  vegetable  incineration.  This  earth  is  ufually  combined 
with  the  carbonick.  Scheele  has  proved  that  it  efflorefces  iti 
this  form  on  the  bark  of  guaiacum,  the  afli,  Sec.  It  is  likewife 
very  often  united  with  the  acid  of  vegetation.  It  appears  to  be 
formed  by  an  alteration  of  the  mucilage,  more  advanced  than 
that  which  forms  the  fecula,  which  has  fome  analogy  with  this 
earth.  We  evidently  fee  the  tranfition  of  mucilage  to  the  (late 
of  earth  in  teftaceous  animals.  We  obferve  the  mucilage  pu- 
3.„0 


4^o  Expreffed  Juices  of  Vegetahles, 

trefy  at  its  furface,  with  fo  much  the  more  facility  as  it  is  purer, 

as  we  may  judge  by  a  comparifon  of  the  afterise,  the  fea  hedge- 
hog, the  crab,  &c. 

Next  to  lime,  alumine  is  the  mofl  abundant  earth  in  vegeta- 
bles, and  next  magnefia.  M.  Darcet  has  obtained,  from  one 
pound  of  the  afhes  of  beech,  one  ounce  of  the  fulphate  of  mag- 
nefia, by  treating  them  with  the  fulphurick  acid.  This  earth  is 
very  abundant  in  the  aflies  of  tamarifc.  Siliceous  earth  likewife 
exifls,  but  lefs  abundantly.  The  lead  common  of  all  is  the 
barytes. 


ARTICLE  XVI. 

Of  the  common  Juices  extraded  by  Incifion  or  Expreffion. 

The  vegetable  juices  hitherto  treated  of  are  peculiar  fubftan- 
ces  contained  in  vegetables,  and  pofiefTing  ftriking  characters, 
by  which  ihey  are  diftinguiiliable  from  every  other  humour. 
But  we  may  at  once  extract  from  vegetables  all  the  juices  they 
contain  ;  and  this  mixture  of  various  principles  may  be  obtained 
by  feveral  methods.  Simple  incifion  is  fometimes  futficient  j 
but  expreffion  is  equally  ufed. 

The  juices  of  vegetables  vary  according  to  the  refpe6live  na- 
ture of  the  plants.  They  are  more  abundant  in  fome  than  in 
others.  Aoc  modifies  them.  Young  trees  in  general  have  mofi 
fap  ;  and  this  fap  is  milder,  more  mucilaginous,  and  lefs  charg- 
ed with  oil  and  refm.  The  fap  varies  according  to  the  feafon. 
In  the  fpring  the  plants  draw  up  with  avidity  the  juices  afforded 
by  the  air  and  the  earth  ;  thefe  juices  eilablifh  a  plethora  every 
■where," from  which  refults  a  confiderable  growth  of  the  individ- 
ual, and  fometimes  a  natural  extravafation.  If  in  the  time  of 
plethora  incifions  be  made  in  any  part  of  the  vegetable,  all  the 
abundant  fap  efcapesby  the  aperture  •,  and  this  fluid  is  almofl 
always  clear,  and  without  fmell.  But  by  degrees  the  plant  elab- 
orates thefe  juices,  and  gives  them  peculiar  characters.  In  the 
fpring  the  fap  in  the  body  of  the  vegetable  prefents  only  a  flight 
alteration  of  the  nutritive  juices  ;  but  in  the  fummer  the  whole 
is  elaborated,  all  is  digefted,  and  then  the  fap  pofiefles  charafters 
very  difi'erent  from  thofe  it  poflefled  during  the  fpring  feafon. 
If  incifions  be  now  made  in  the  tree,  the  juices  obtained  are  ac- 
cordingly very  different  j  and  for  this  reafon  it  is  that  the  juices 
difperfed  in  commerce  are  extracted  during  the  fummer. 

The  conflitution  of  the  air  equally  influences  the  nature  of 
vegetable  juices.  A  rainy  feafon  oppofes  the  developement  of 
the  facchai'ine  principle,  as  well  as  tlie.  formation  of  rcfms  and 


ExtraBion  of  Manna,  4pr 

aromatick  fubftances.  A  dry  feafon  affords  little  mucilage,  but 
much  refin  and  aromatick  principle  ;  hot  weather  decompofes 
the  mucilage,  and  favours  the  development  of  refin,  faccharine 
matter,  and  aroma  ;  but  a  cold  feafon  does  not  permit  the  for- 
mation of  any  principle  but  mucilage  :  and  as  the  mucilage  is  the 
principle  of  increafeof  bulk  in  plants,  the  whole  of  this  fubflance 
is  employed  for  that  purpofe  ;  while  the  heat  and  light  modi- 
fy the  fame  mucilage,  and  caufe  it  to  pafs  to  the  ftate  of  oil,  re- 
fm,  aroma,  &c.  Hence  probably  it  is  that  trees  have  a  more 
agreeable  appearance  in  cold  than  ia  burning  climates  ;  and  that 
the  trees  in  this  latter  fituation  abound  with  aromatick,  oily,  and 
refinous  principles.  In  the  vegetable  as  in  the  animal  kingdom, 
fpirit  appears  to  be  the  portion  of  the  fouthcrn  climates  ;  while 
iorce  and  ftrength  are  attributes  of  the  northern. 

Concerning  the  Juices  extrad>ed  by  Incifion, 

The  juice  contained  in  plants,  and  known  by  the  name  of  Sap, 
is  difperfed  through  the  cellular  tiffue,  inclofed  in  the  veiTels,  or 
depofited  in  the  utricules  :  and  there  is  a  communication  exift- 
ing,  which,  when  any  part  of  the  vegetable  is  wounded,  caufes 
the  abundant  juices  to  flow  through  the  aperture  ;  not  indeed  fo 
fpeedily,  nor  lb  completely,  as  in  animals  \  becaufe  the  humours 
do  not  polTefs  fo  rapid  a  motion,  and  becaufe  there  is  lefs  con- 
nexion between  the  feveral  organs  in  vegetables  than  in  animals. 
The  fap  is  a  confufed  mixture  of  all  the  principles  of  vegetables. 
The  oil  and  the  mucilage  are  confounded  with  the  falts.  It  is 
in  a  word,  the  general  humour  of  vegetables,  in  the  fame  man- 
ner as  the  blood  in  animals.  In  the  prefent  place  vjq  fiiall  fpeak 
only  of  manna  and  opium. 

I.  Manna. — Several  vegetables  afford  manna  ;  and  it  Is  ex- 
traiEled  from  the  pine,  the  fir,  the  maple,  the  oak,  the  juniper, 
the  fig,  the  willow,  the  olive,  &c.  but  the  afh,  larch,  and  the  al- 
hagi,  afford  it  in  the  largeft  quantities.  L'obel,  Rondelet,  and 
others,  have  obferved  at  Montpellier,  upon  the  olive  trees,  akind 
of  manna,  to  which  they  have  given  the  name  of  oeliomeli. 
Tournefort  colleded  it  from  the  fame  trees  at  Aix,  and  at  Tou- 
lon. 

The  afli  which  affords  manna  grows  naturally  in  all  temper- 
ate climates  :  but  Calabria  and  Sicily  appear  to  be  the  moft  nat- 
ural countries  to  this  tree  ;  or  atlealt  it  is  only  in  thefe  coun^ 
tries  that  it  abundantly  furnilhes  the  juice  called  Manna  in  com- 
merce. 

The  manna  flows  naturally  from  this  tree,  and  attaches  itfelf 
to  its  fides  in  the  form  of  white  tranfparent  drops  5  but  the  ex- 


4^2  Chara^ers  of  Manna. 

tra£lion  of  this  juice  is  facilitated  by  incifions  made  in  the  trc« 
during  funimer  :  the  manna  flows  through  thefe  apertures  up- 
on the  trunk  of  the  tree,  from  which  it  is  detached  with  wood- 
en inftruments.  Care  is  Ukewife  taken  to  infert  draws,  or  fmall 
Hicks  of  wood,  into  tliefe  incifions  ;  and  the  flaladites  which 
hang  from  thefe  fmall  bodies  are  feparated,  and  known  in  com- 
merce by  the  name  of  Manna  in  Tears  :  the  fmalleft  pieces  form 
the  manna  in  forts  or  flakes  ;  and  the  common  or  fat  manna  ig 
of  the  word  quality,  becaufe  the  moil  contaminated  with  earth 
and  other  foreign  fubftances.  The  aih  fometimes  affbrds  man- 
na in  our  climates,  fpecimens  of  which  I  have  feen  coUecled  in 
the  vicinity  of  Aniane. 

The  larch  which  grows  abundantly  in  Dauphiny,  and  the  en- 
virons of  Briangon,  likewife  aflx)rds  manna.  It  is  formed  dur- 
ing the  fummer  on  the  fibres  of  the  leaves,  in  white  friable 
grains,  which  the  peafants  coUedl  and  put  into  pots,  which  they 
keep  in  a  cool  place.  This  manna  is  of  a  yellow  colour,  and  has 
^  very  naufeous  fmell. 

The  alhagi  is  a  kind  of  broom,  which  grows  in  Perfia.  A 
juice  tranfndes  from  its  leaves,  in  the  form  of  drops  of  various 
iizes,  which  the  heat  of  the  fun  indurates.  An  interefting  ac- 
count of  this  tree  may  be  feen  in  Tournefort's  Travels.  This 
manna  is  known  in  the  Levant,  in  the  town  of  Tauris,  by  the 
name  of  Tereniabin. 

The  manna  mofl:  frequently  ufed  is  that  of  Calabria.  Its 
fmell  is  ftrong,  and  its  tafte  fweetifh  and  naufeous  :  if  cxpofed 
on  hot  coals,  it  fwells  up,  takes  fire,  and  leaves  a  light  bulky  coal. 

"Water  totally  diflblves  it,  whether  hot  or  cold.  If  it  be  boil- 
ed vj'Vih.  lime,  clarified  with  white  of  egg,  and  concentrated  by 
evjporation,  it  affords  cryftals  of  fugar. 

Manna  affords  by  dillillation  water,  acid,  oil,  and  ammoniack  \ 
and  its  coal  affords  alkali. 

This  fubftance  forms  the  bafis  of  mod  purgative  medicines. 

2.  Opium.— The  plant  which  affords  opium  is  the  poppy, 
which  is  cultivated  in  Perfia  and  Afia  Minor.  To  extrad  this 
precious  medicine,  care  is  taken  to  cut  off  all  the  flowers  which 
would  load  the  plant,  and  to  leave  that  only  which  correfponds 
with  the  principal  dem.  At  the  beginning  of  fum.mer,  when 
the  poppy-heads  are  ripe,  incifions  are  made  quite  round  them, 
from  which  tears  flow  that  are  carefully  colleded.  This  opium 
i^-i  the  pured,  and  is  retained  in  the  country  for  various  ufes. 
That  which  comes  to  us  is  extrafled  by  preffure  from  the  fame 
heads.  The  juice  thus  obtained  is  wrapped  up,  after  previous 
frying,  in  the  leaves  of  the  poppy, ,  and  comes  to  us  in  the  form 
of  circular  flattened  cal^es^ 


ExtraBion  of  Opium,  ^pj 

In  our  laboratories  it  is  cleared  from  its  impurities  by  folution 
in  hot  water,  filtration,  and  evaporation  to  the  confiftence  of  an 
extraft.     This  is  the  extract  of  opium. 

Opium  contains  a  ilrong  and  narcotick  aroma,  from  which  it 
is  impolTible  to  clear  it,  according  to  Mr.  Lorry.  It  likewife 
contains  an  extratt  foluhle  in  water,  and  a  refin  ;  together  with 
a  volatile  concrete  oil,  and  a  peculiar  fait. 

By  long  digeilion  in  hot  water  the  volatile  oil  becomes  atten- 
uated, is  difengaged,  and  carries  the  aroma  with  it  j  fo  that  by 
this  means  the  oil  and  aroma  may  be  feparated,  at  lead  for  the 
moft  part.  It  has  been  obferved  that  opium  deprived  of  this 
oil,  a  portion  of  its  aroma,  and  its  refin,  preferved  its  fedative 
virtue,  without  being  narcotick  and  ftupifying.  We  are  in- 
debted to  Baume  for  a  feries  of  interefting  refearches'  on  this 
fubje^l.  He  boiled  four  pounds  of  fliced  opium  in  between 
twelve  and  fifteen  pints  of  water,  for  half  an  hour.  The  de- 
co6lion  was  (trained  with  prefTurq,  the  dregs  were  exhaufted  by 
ebullition  with  more  water.  All  thefe  waters  were  mixed  to- 
gether, and  reduced  by  evaporation  to  fix  pints.  The  liquor 
was  then  put  into  a  cucurbit  of  tin,  and  digeited  on  a  fand- 
bath  for  fix  months,  or  during  three  months  night  and  day. 
Care  was  taken  to  add  water  as  the  evaporation  proceeded  ;  and 
the  bottom  of  the  veflel  was  fcraped  from  time  to  time,  to  dif- 
engage  the  refinous  matter  which  fubfided.  When  the  digeftioa 
was  finifhed,  the  liquor  was  filtered,  the  refidue  carefully  fepa- 
rated, and  the  water  evaporated  to  the  confidence  of  an  extract. 

If  the  fait  be  required  to  be  feparated,  the  evaporation  muft 
be  fufpended  when  the  fluid  is  reduced  to  one  pint.  An  earthy 
fak  falls  down  by  cooling,  which  is  of  a  ruddy  appearance,  and 
has  the  form  of  fcales  mixed  with  needled  cryftals. 

By  this  long  but  judicious  procefs,  the  oil  is  firft  feparated  j 
which  after  three  or  four  days  rifes  to  the  furface  of  the  liquor, 
where  it  forms  an  adhefive  pellicle,  like  turpentine.  This  pel- 
licle is  gradually  diflipated,  and  difappears  at  the  end  of  a  month, 
nothing  more  being  feen  than  a  icw  drops  from  time  to  time. 
In  proportion  as  the  oil  is  diflipated,  the  refin,  which  formed  a 
foap  with  it,  is  precipitated. 

Mr.  Baume  has  calculated  that  thefe  principles  exift  in  the 
following  proportions  : — Four  pounds  of  common  opium  afford 
one  pound  one  ounce  of  marc  or  infoluble  matter,  one  pound 
fifteen  ounces  of  ^xtratSt,  twelve  ounces  of  refin,  one  gros  or 
dram  of  fait,  three  ounces  {(tvcn  gros  of  denfe  oil  or  aroma. 

Mr.  Bocquet  propofed  to  extract  the  fedative  principle,  bydif- 
folvingit  in  the  cold,  and  afterwards  evaporating  it  ;  Mr.  Joile, 
^/  agitating  it  in  cold  wat^r  j  Melli:^.  De  Laflbae  and  Cornette, 


JJ94  Exprejfed  Vegetable  Juices, 

by  diflblving,  filtering  it  feveral  times,  and  always  evaporating  it 
to  the  ccnfillence  of  an  extradl:. 

The  ledative  principle  is  a  medicine  of  the  greateft  value,  be- 
caufe  it  does  not  produce  that  drunkennefs  and  ftupor  which  are 
too  commonly  the  efFe£ls  of  crude  opium. 

When  a  plant  does  not  afford  its  juice  by  incifion,  this  may 
happen  either  becaufe  the  quantity  is  too  fmall,  or  becaufe  its  con- 
fidence is  not  fufficiently  fluid  ;  or  becaufe  there  is  not  a  fufh- 
ciently  perfe^H:  communication  between  the  veffels  of  the  plant 
to  permit  the  flowing  of  all  the  juice.  In  thefe  cafes  the  defired 
effetl  may  be  produced  either  by  fimple  mechanical  prefTure,  as 
in  extracting  the  juice  of  hypociftus  and  acacia  ;  or  by  the  aflTift- 
ance  of  water,  which  fofteils  the  texture  of  the  vegetable,  at  the 
fame  time  that  it  difTolves  and  carries  off  the  juice. 

Concerning  Vegetable  Juices  extrafted  by  PrefTure. 

The  fucculent  vegetables  afford  their  juice  by  fimple  prefTure; 
and  the  method  of  performing  this  operation  is  nearly  the  fame 
in  all  plants.  When  it  is  intended  to  extract  the  juice  of  a  plant 
it  is  wafhed,  cut  into  fmall  pieces,  pounded  in  a  marble  mortar, 
put  into  a  linen  bag,  and  prefied  in  a  prefs. 

There  are  fome  ligneous  plants,  fuch  as  fage,  thyme  and  the 
lefler  centaury,  whole  juices  cannot  be  extracted  without  the  ad- 
dition of  a  fmall  quantity  of  water  \  there  are  other  very  fuccu- 
lent plants,  fuch  as  borage,  burglofs  and  chicory,  whofe  juices  are 
fo  vifcid  and  mucilaginous,  as  not  to  pafs  through  a  cloth  unlefs  a 
fmall  quantity  of  water  be  added  during  the  pounding.  Inodo- 
rous plants  may  likewife  be  left  to  macerate,  in  order  to  prepare 
them  for  the  extraiflion  of  their  juices.  The  vegetable  juices 
may  be  clarified  by  fimple  repofe,  or  by  filtration  ;  when  very 
fiuid,  by  white  of  egg,  or  animallymph,  boiled  with  them  ,  and 
when  the  juices  contain  principles  which  may  be  evaporated, 
fuch  as  thole  of  fage,  balm,  marjorum,  &c.  the  vial  which  contains 
the  juice  is  plunged  into  boiling  water,  after  having  clofed  it 
with  a  paper  with  a  hole  pierced  through  it ;  and  when  the 
juice  is  clarified,  it  is  taken  out,  dipped  in  cold  water,  and  de-p 
jcanted- 

The  juice  of  acacia  is  extra£led  from  the  fame  tree  which  af- 
fords gum  arabick.  The  fruits  of  this  tree  are  collected  before 
they  are  ripe  5  then  pounded,  prefTed,  and  the  juice  dried  in  the 
fun  :  it  forms  balls  of  a  blackilh  brown  internally,  redder  ex- 
ternally, and  of  an  aflringent  tafte. 

A  juice  is  prepared  with  unripe  floes,  which  is  fold  under  the 
name  of  German  Acacia,  and  does  not  differ  much  from  that 
of  Egypt. 


■t.^. 


Vegetable  Oxigenous  Gas,  495 

The  juice  of  hypoclftus  is  extra£led  from  a  parafitkal  plant 
winch  grows  on  the  ciftus  in  the  ifland  of  Crete.  The  fruit  is 
pounded,  the  juice  extraded  by  preflure,  and  thickened  in  the 
fun  ;  it  becomes  black,  and  of  a  firm  confiftence. 

Thcfe  two  iait  mentioned  juices  are  ufed  in   medicine  as  af* 


I 


SECTION    IV. 

Concerning  fuch  principles  as  efcape  from  Vegetables  by  Traiifpiration^ 

Vegetables,  being  endued  withdigeftive  organs, 
throw  off  all  fuch  principles  as  cannot  be  aflimilated  by  them  5 
and  when  the  funflions  of  the  vegetable  are  not  favoured  by 
fuch  caufes  as  facilitate  them  the  nutritive  juices  are  rejected 
nearly  unaltered.  We  fliall  here  attend  to  three  principal 
fubftances  that  exhale  from  vegetables,  viz.  air,  water,  and 
aroma. 

ARTICLE    I. 

Concerning  Oxigenous  Qas  afforded  by  Vegetiibies. 

Dr.  Ingenhoufz  pubhfhed,  in  the  year  1779,  Experiments 
upon  Vegetables,  in  which  he  affirms  that  plants  poffefs  the  prop- 
erty of  emitting  vital  air  when  aded  upon  by  tfie  direcSl  rays  of 
the  fun  ;  and  that  they  emit  a  very  mephitick  air  in  the  (hade, 
and  during  the  night. 

Do61:or  Prieftly  made  known  the  fame  refults  at  the  fame  time, 
as  well  as  Mr.  Senebier  of  Geneva,  who  neverthelefs  did  not 
publilh  a  work  on  this  fubje<£t  until  the  year  1782,  in  which  he 
admits,  as  a  general  principle,  that  plants  fuffer  vital  air  to  ef- 
cape in  the  fun  ihine :  but  he  maintains  that  they  do  not  pro- 
duce mephitick  air  in  the  fliade  i  and  is  of  opinion  that,  if  Dr. 
Ingenhoufz  obtained  any,  it  arofe  from  a  commencement  of  pu- 
trefaclion  in  the  plant. 

The  fimpleft  pFocefs  for  extra£ling  this  gas  from  vegetables, 
confifts  in  immerfing  them  under  water,  beneath  an  inverted 
glaf<  vefTel.  It  is  then  f.en,  when  the  fun  ads  on  the  plant, 
that  frnall  bubbles  are  emitted,  which  gradually  grow  larger,  a- 
rife  from  the  fibres  of  the  leaf,  and  afcend  to  the  furface  of  tlw 
fluid. 


49^  Vegetable  Oxigenous  Gas, 

All  plants  do  not  afford  gas  with  the  fame  facility.  There 
are  fome  which  emit  it  the  moment  the  fun  atis  upon  them  : 
fuch  are  the  leaves  of  the  jacobaea,  of  lavender,  and  of  fome  aro- 
matick  plants.  In  other  plants  the  emiffion  is  flower  ;  but  in 
none  later  than  feven  or  eight  minutes,  provided  the  fun's  light 
be  ftrong.  The  air  is  almolt  totally  furnifhed  by  the  inferlour 
furface  of  the  leaves  of  trees  :  it  is  not  the  fame  with  herbs  *,  for 
thefe  afford  air  from  nearly  the  whole  of  their  furface,  accord- 
ing to  Senebier. 

The  leaves  afford  more  air  when  attached  to  the  plant  than 
when  gathered  ;  and  the  quantity  is  likewife  greater  the  frefher 
and  founder  they  are. 

Young  leaves  afford  but  a  fmall  quantity  of  vital  air  ;  thofe 
which  are  full  grown  afford  more,  and  the  more  the  greener 
they  are.  Leaves  which  are  injured,  yellow,  or  red,  do  not  af- 
ford it. 

Frefh  leaves  cut  in  pieces  afford  air  ;  and  the  oxigene  gas 
is  capable  of  being  emitted  without  the  plant  being  plunged 
underwater,  as  is  proved  from  the  experiments  of  Mr.  Senebier. 
The  parenchym.a  of  the  leaf  appears  to  be  the  part  which  e- 
mitsthe  air.  The  epidermis,  the  bark,  and  the  white  petals,  do 
not  afford  air  j  and  in  general  it  is  only  the  green  part  of  plants 
which  affords  oxigenous  gas.  Green  fruits  afford  air,  but  thofe 
which  are  ripe  do  not  :  and  the  fame  is  true  of  grain. 

It  is  proved  that  the  fun  does  not  zOl  in  the  producllon  of 
this  phenomenon  as  a  body  which  heats.  The  emiffion  of  this 
gas  is  determined  by  the  light  ;  and  I  have  even  obferved  that 
a  ftrong  light,  without  the  dire<^  aftion  of  the  fun's  rays,  is  fuf- 
ficient  to  produce  this  phenomenon. 

It  is  proved  by  the  experiments  of  Mr.  ^enebier,  that  an  acid 
diluted  in  water  increafes  the  quantity  of  air  which  is  difenga- 
ged,  when  the  water  is  not  too  much  acidulated  ;  and  in  this 
cafe  the  acid  is  decompofed. 

It  has  been  obferved  that  the  conferva  affords  much  vital  air  ; 
as  well  as  the  green  matter  which  is  formed  in  water,  and  is  fup- 
pofed  by  Ingenhoufz  to  be  a  colletlion  of  greenifh  inledls. 

Pure  air  is  therefore  feparated  from  the  plant  by  the  action  of 
light  :  and  the  excretion  is  llronger  accordingly  as  the  light  is 
more  vivid.  It  feems  that  light  favours  the  work  of  digeftion 
in  the  plant  ;  and  that  the  vital  air,  which  is  one  of  the  princi- 
ples of  almcft  all  the  nutritive  juices,  more  efpecially  of  water, 
is  emitted,  v/hen  it  finds  no  fubllance  to  combine  uithin  the 
vegetable.  Hence  it  arifes  that  plants  whofe  vegetation  is.  the 
mod  vigorous,  afford  the  grcateft  quantity  of  air  ;  and  hence 
likewife  it  is  that  a  fmal!  quantity  of  the  acid   mixed  with   the 


AromOi  or  Spiritas  Re^or.  4^)7 

water  favours  the  cmiflion  and  indrcafes  the  quantity   of  oxige- 
nous  gas. 

By  this  continual  emifiion  of  vital  air,  the  Author  of  nature 
incefTancly  repairs  the  lofs  which  is  produced  by  refplration, 
combultion,  and  the  alteration  of  bodies,  which  comprehends 
every  kind  of  fermentation  and  putrefaction  ;  and  in  this  man- 
ner the  equilibrium  between  the  conitituent  pruiciplcs  of  the  at- 
mofphere  is  always  kept  up. 


ARTICLE  II. 

Concerning  the  Water  afforded  by  Vegetables. 

Plants  likewife  emit  a  confiderable  quantity  of  water,  in  the 
form  of  vapour,  through  their  pores  j  and  this  excretion  may  be 
eftimated  as  the  moft  abundant.  Hales  has  calculated  that  the 
tranfpiration  of  an  adult  plant,  fuch  as  the  helianthus  annuus, 
was  in  fummer  feven  times  more  confiderable  than  that  of  man. 

Guettard  has  obferved  that  this  excretion  is  always  in  propor- 
tion to  the  intenfity  of  the  light,  and  not  of  the  heat  ;  fo  that 
there  is  fcarcely  any  during  the  night.  The  fame  philofopher 
has  obferved  that  the  aqueous  tranfpiration  is  more  efpecially 
made  from  the  other  furface  of  the  leaf.  The  water  which  ex- 
hales from  vegetables  is  not  pure,  but  ferves  as  the  vehicle  of 
the  aroma  ;  and  even  carries  with  it  a  fmall  quantity  of  extract- 
ive matter,  which  caufes  it  to  corrupt  fo  fpeedily. 

The  immediate  efletft  of  the  aqueous  evaporation  confifts  In 
maintaining  a  degree  of  coolnefs  in  the  plant,  which  prevents 
it€  afluming  the  temperature  of  the  atmofphere. 
#. 

ARTICLE    III. 

Concerning  the  Aroma,  or  Splritus  RetSlor. 

Each  plant  has  its  characleriflick  fmell.  This  odorant  prin- 
ciple was  diftlngulfhed  by  Boerhaave  by  the  name  of  Splritus 
Re£lor,  and  by  the  moderns  under  the  name  of  Aroma. 

The  aroma  appears  to  be  of  the  nature  of  gas,  from  its  fine- 
nefs,  its  invifibtlity,  &c.  The  flighted  heat  is  fufficient  to  ex- 
pel it  from  plants.  Coolnefs  condcnfes  it,  and  renders  it  more 
fenfible  ;  and  on  this  account  the  fmell  of  plants  Is  much  ftxong- 
cr  in  the  morning  and  evening. 
3...P 


493     \  Exhalations  of  Plants, 

This  principle  is  fo  fubtile,  that  fhe  continual  emiflion  of  it 
from  a  wood  or  flower  does  not  diminifti  its  weight,  even  aft^ 
a  very  confiderable  time. 

The  aroma  is  fometimes  fixed  in  an  extract,  fometimes  in  an 
oil,  and  this  laft  combination  is  the  moft  ufual.  It  even  appears 
to  conftitute  the  volatile  charader  of  the  elTential  or  volatile 
oils. 

The  nature  of  the  aroma  appears  to  vary  prodigioufly ;  at 
leafl;  if  we  may  judge  by  the  organ  of  fmell,  which  diftinguiflies 
feveral  fpecies.  There  are  fome  which  have  a  naufeous  or  poi- 
fonous  eiFe£l  on  the  animal  economy.  Ingenhoufz  quotes  an 
inftance  of  the  death  of  a  young  woman  occafioned  by  the 
fmell  of  lilies,  in  17 19  ;  and  the  famous  Triller  reports  the  ex- 
ample of  a  young  woman  who  died  in  confequence  of  the  fmell 
of  violets,  while  another  was  faved  by  removing  the  flowers. 
Martin  us  Cromerus  exhibits  likewife  an  example  of  abifhop  of 
Breflau  who  died  by  a  fimilar  caufe. 

The  mancenille  tree  which  grows  in  the  Weft-Indies  emits 
very  dangerous  vapours.  The  humour  which  flows  from  this 
tree  is  fo  unwholefome,  that  if  it  drop  on  the  hand  it  raifes  a 
bHfter. 

The  American  plant  lobelia  longiflora  produces  a  fufibcating 
opprefllon  in  the  breaft  of  thofe  who  refpire  in  its  vicinity,  ac- 
cording to  Jacquin,  Hortus  Vindobonenfis.  The  rhus  toxico- 
dendron emits  fo  dangerous  an  exhalation,  that  Ingenhoufz  at- 
tributes the  return  of  a  periodical  diforder,  which  attacked  the 
family  of  the  curate  of  Croflen  in  Germany,  to  a  bench  (haded 
by  this  tree,  under  which  they  had  the  cuftom  of  fitting.  Eve- 
ry one  knows  the  efi^e<fl:s  of  muflc  and  priental  faffron  on  certain 
perfons  ;  and  the  exhalation  of  the  walnut-tree  is  confidered  as 
very  unwholeforae.  .^ 

We  may  here  mention  the  noxious  property  of  thofe  canes 
or  reeds  which  in  this  country  are  ufed  to  cover  roofs  and  dung- 
hills, &c.  Mr.  Poitiven  faw  a  man  who  was  very  ill  on  account 
of  having  handled  thefe  canes  :  the  parts  of  generation  were  pro- 
digioufly fwelled.  A  dog  which  had  flept  upon  the  reeds  fuf- 
fered  in  the  fame  manner,  and  was  atTedled  in  the  fame  parts. 

The  method  of  extradling  the  aroma  varies  according  to  itj 
volatility  and  affinities.  It  is  in  general  foluble  in  water,  alco- 
hol, oils,  &c.  •,  and  thefe  fluids  are  feverally  employed  to  cxtradl 
it  from  plants  which  aflx)rd  it. 

When  water  or  alcohol  are  ufed,  they  are  diftilled  by  a  gentle 
heat,  and  the  aroma  comes  over  with  them.  Simple  infufion 
may  be  ufed  5  and  in  this  way  the  lofs  of  a  portion  of  the  aroma 
is  avoided. 


Decompofition  of  Vegetables.  ^#^ 

Water  charged  with  aroma  is  known  by  the  name  of  the  dif- 
tilled  water  of  the  fubflance  made  ufe  of.  The  diftilled  water 
of  inodorous  or  herbaceous  plants  does  not  appear  to  poflefs 
any  virtue ;  and  the  apothecaries  have  long  fince  decided  the 
queftion,  by  fubftituting  fpring  water  in  its  place.  Spirit  of 
wine  combined  with  the  fame  principle,  is  known  by  the  name 
of  the  fpirit  or  quinteflence  of  the  vegetable. 

When  the  aroma  is  very  fugacious,  fuch  as  that  of  lilies,  jaf- 
mine,  or  tuberofe,  the  flowers  are  put  into  a  tin  cucurbit  with 
cotton  ftceped  in  oil  of  ben.  The  cotton  and  the  flowers  are  dif- 
pofed  in  alternate  layers  ;  the  cucurbit  is  clofed,  and  a  gentle 
icat  applied.  In  this  manner  the  aroma  is  permanently  combi- 
ned with  the  oil. 

Thefe  are  the  three  methods  ufed  to  retain  the  odorant  prin- 
ciple. The  art  of  the  perfumer  confifts  in  applying  them  at 
pleafure  to  various  fubftances. 

Perfumes  are  either  dry  or  liquid.  Among  the  lirfl;  we  may 
place  the  fachets,  or  little  perfumed  bags,  which  contain  either 
mixtures  of  aromatick  plants,  or  aromas  in  their  native  ftate  ; 
the  perfumed  powders,  which  obtain  their  fmell  by  a  few  drops 
of  the  folution  of  aroma  \  the  pafl:illes  '  or  confits  which  have 
fugar  for  their  bafis,  &c. 

Liquid  perfumes  mod  commonly  con  lift  of  aroma  diflblved 
in  water  or  alcohol ;  the  various  liqueurs,  or  fcented  fpirituous 
cordial  waters,  are  nothing  elfe  but  the  fame  folutions  diluted 
•with  water,  and  fweetened  with  fugar. 

For  example,  to  make  the  eau  divine,  the  bark  of  four  citrons 
is  taken,  and  put  into  a  glafs  alembick,  with  two  pounds  of  good 
fpirit  of  wine,  and  two  ounces  of  good  orange  flower  water  ;  af- 
ter which,  diftillation  is  performed  on  the  fand-bath.  On  the 
other  hand,  one  pound  and  a  half  of  fugar  is  diflblved  in  one 
pound  and  a  half  of  water.  The  two  liquors  being  mixed,  be- 
come turbid  5  but,  being  left  to  Hand,  the  refult  is  an  agreeable 
liquor. 

To  make  the  cream  of  rofes,  I  take  equal  parts  of  rofe  water, 
fpirit  of  wine  a  la  rofe,  and  fyrup  of  fugar.  I  mix  thefe  three 
fubfli^nces,  and  colour  the  mixture  with  the  infufion  cochenille. 

But  it  mufl:  be  allowed  that,  in  all  perfumes  which  are  a  lit- 
tle complicated,  the  nofe  is  the  bed  chemifl:  that  can  be  confult- 
cd  ;  and  a  good  nofe  is  as  requifite  and  eflential  to  a  perfumer, 
as  a  ftrong  head  is  to  a  geometer. 


500  Di/iillatton  of  Vegetables. 

SECTION   V. 

Concerning  the  Alterations  to  which  Vegetables  are  fuhjecl  after  they  are 


deprived  ot  life. 


Ti 


HE  fame  principles  which  maintain  life  in  vegetables 
and  animals,  become  the  fpeedieft  agents  of  their  deftru£lion 
when  dead.  Nature  feems  to  have  entrufled  the  compofition, 
maintenance  and  decompofition  of  thefe  beings  to  the  fame  a- 
gents.  Air  and  water  are  the  two  principles  which  maintain 
the  life  in  living  beings  ;  but  the  moment  they  are  dead  they 
haften  their  alteration  and  diflblution.  The  heat  itfelf,  which 
aflifted  and  fomented  the  fun6lions  of  life,  concurs  to  facilitate 
the  decompofition.  Thus  it  is  that  the  frofls  of  Siberia  pre- 
ferve  bodies  for  feveral  months  ;  and  that  in  our  mountains 
they  are  kept  for  a  long  time  on  the  fnow,  when  it  intercepts  the 
carrying  them  to  the  place  of  interment. 

We  fiiall  examine  the  atftion  of  thefe  three  agents,^  namely, 
heat,  air,  and  water  ;  and  we  fliall  endeavour  to  fhdw  the  pow- 
er and  effc6l  of  each  before  we  Ihali  attend  to  their  combined 
adlion. 


CHAPTER  I. 

Concerning  tlie  ae^lion  of  Heat  upon  Vegetable  Subflances. 

THE  diftillation  of  plants  by  a  naked  fire  is  nothing  but  the 
a£l:  of  decompofmg  them  by  means  of  fimple  heat.  This  pro- 
cefs  was  for  a  long  time  the  only  method  of  analyfis.  The  firft 
chemifts  of  Paris  adopted  it  for  the  analyfis  of  near  one  thou- 
fand  four  hundred  plants  :  and  it  was  not  till  the  commence- 
ment of  the  prefent  century  that  this  labour  was  difcontinued  j 
a  labour  which  did  not  feem  to  advance  the  fcience,  fince  in  this 
way  the  cabbage  and  hemlock  afforded  the  fame  produ£ls. 

It  is  clear  that  an  analyfis  by  the  retort  ought  not  to  fliow  the 
principles  of  vegetation  :  for,  not  to  mention  that  heat  changes 
their  nature  by  becoming  a  conflituent  part  of  the  principles  ex- 
tracted; thefe  principles  themfelves  become  mixed  together,  and 
we  can  never  know  their  order  or  flate  while  in  the  living  plant. 
The  action  of  the  heat  moreover  caufes  the  vegetable  principles 
to  rea£l  upon  each  other,  and  confounds  the  whole  together. 
Whence  it  arifes  that  all  vegetables  afford  nearly  the  fame  prin- 


Dijlillation  of  Vegetables,  £©1 

ciplcs  ;  namely,  water,  an  oil  more  or  lefs  thick,  an  acid  liquor, 
a  concrete  fait,  and  a  coal  or  caput  mortuum,  more  or  lefs  abun- 
dant. 

Hales  took  notice  that  the  diftillation  of  vegetables  aiforded 
much  air  ;  and  was  even  in  poflefiion  of  an  apparatus  to  colle£l 
and  meafure  it.  But  in  our  time  the  methods  of  colledling  and 
confining  the  gaffes  are  fimplified  ;  and  the  hydro-pneumatick 
apparatus  has  proved  that  the  fubftanccs  are  formed  of  a  mix- 
ture of  carbonick  acid,  hydrogene,  and  fometimes  a  little  nitre 
gene. 

The  order  in  which  the  feveral  produ(fls  are  obtained,  and  the 
charafters  they  exhibit,  lead  us  to  the  following  obfervations  : 

1.  The  water  which  pafles  firft  is  ufually  pure,  and  without 
fmell  *,  but  when  odorant  plants  are  diftilled,  the  firfh  drops  are 
impregnated  with  their  aroma.  Thefe  firft  portions  of  water 
confift  of  that  which  was  fuperabundant,  and  impregnated  the 
vegetable  tiffue.  When  the  water  of  compofition,  or  that  which 
was  in  combination  with  the  vegetable,  begins  to  rife,  it  carries 
along  with  it  a  fmall  quantity  of  oil,  which  colours  it ;  and 
fome  portions  of  a  weak  acid,  afforded  by  the  mucilage  and  oth- 
er principles  with  which  it  exifted  in  the  fapohaceous  Hate.  The 
phlegm  likewife  very  often  contains  a  fmall  quantity  of  ammoni- 
ack :  and  this  alkali  appears  to  be  formed  in  the  operation  itfelf ; 
for  there  are  few  plants  which  contain  it  in  their  natural 
itate. 

2.  To  the  phlegm  fucceeds  an  oily  principle,  little  coloured  at 
firft  ;  but  in  proportion  as  the  diftillation  advances,  the  oil  which 
rifes  is  thicker,  and  more  coloured.  They  are  all  chara£lerlzed 
by  a  fmell  of  burning,  and  an  acrid  tafte,  that  arife  from  the  im- 
preffion  of  the  fire  itfelf.  Thefe  oils  are  moft  of  them  refinous, 
and  the  nitrick  acid  eafily  inflames  them.  They  may  be  render- 
ed more  fluid  and  volatile  by  repeated  dift illations. 

3.  In  proportion  as  the  oil  comes  over,  there  fometimes  dif- 
tils  carbonate  of  ammoniack,  which  attaches  itfelf  to  the  fides  of 
the  vefl^els.  It  is  ufually  foiled  with  an  oil  which  colours  it. 
This  fait  does  not  appear  to  exift  ready  formed  in  vegetables. 
Rouelle  the  younger  proved  that  the  plants  which  aflbrd  the  moft 
of  it,  fuch  as  the  cruciferous  plants,  do  not  contain  it  in  their 
natural  ftate.  It  is  therefore  found  when  its  component  parts 
are  volatilized  and  re-united  by  the  diftillation. 

4.  All  vegetables  afford  a  very  great  quantity  of  gas  by  diftil- 
lation ;  and  their  nature  has  an  influence  on  the  gafeous  fubftan- 
ccs they  afford.  Thofe  plants  which  abound  with  refin,  afford 
much  more  hydrogenous  gas  j  while  fuch  as  abound  with  mucil- 
age produce  carbonick  acid.     The  mixture  of  thefe  gafes  forms 


5  ^^  Properties  of  Charcoal, 

an  air  which  is  heavier  than  the  common  inflammable  air,  on 
which  account  it  has  been  found  very  little  adapted  to  aeroftat- 
ick  experiments. 

The  art  of  charring  wood,  or  converting  it  into  charcoal,  is 
an  operation  neaily  fmiilar  to  the  diftillation  we  have  juft  de- 
fcribed.  It  confifts  in  forming  pyramids  of  wood,  or  cones 
^truncated  at  their  fummit.  The  whole  is  covered  with  earth, 
well  beaten,  leaving  a  lower  and  upper  aperture.  The  mafs 
'^;  is  then  fet  on  fire  ;  and  when  the  whole  is  well  ignited,  the  com- 
buftion  is  flopped  by  clofmg  the  apertures  through  which  the 
current  of  air  pafled.  By  this  means  the  water,  the  oil,  and  all 
the  principles  of  the  vegetable  are  diflipated,  except  the  fibre. 
The  wood  in  this  operation  lofes  three  fourths  of  its  weight,  and 
one  fourth  of  its  bulk.  According  to  Fontana  and  Morozzo,  it 
abforbs  air  and  water  as  it  cools.  I  am  alTured,  from  my  exper- 
iments in  the  large  way,  that  pitcoal  defulphurated  (coaked)  ac- 
quires twenty-five  pounds  of  water  in  the  quintal  by  cooling  ; 
but  the  coal  of  wood  did  not  appear  to  me  to  abforb  more  than 
fifteen  or  twenty.  The  futurbrand  of  the  Icelanders  is  nothing 
but  wood  converted  into  charcoal  by  the  lava  which  has  fur. 
rounded  it. — See  Von  Troil's  Letters  on  Iceland. 

The  charcoal  which  is  the  refidue  of  all  thefe  diftillation s, 
js  a  fubflance  which  defervcs  an  attention  more  particularly  be- 
caufe  it  enters  into  the  compofition  of  many  bodies,  and  bears  a 
very  great  part  in  their  phenomena. 

Charcoal  is  the  vegetable  fibre  very  flightly  changed.  Itmoft 
commonly  preferves  the  form  of  the  vegetable  which- afforded  it. 
The  primitive  texture  is  not  only  diftinguifhable,  but  ferves  like- 
wife  to  indicate  the  ftate  and  nature  of  the  vegetable  which  has 
afforded  it.  It  is  fomctimes  hard,  fdnorous  and  brittle  j  fome- 
times  light,  fpongy,  and  friable  ;  and  fome  fubftances  afford  it 
in  a  fubtle  powder,  without  confiftencc.  The  coal  of  oils  and 
refins  is  of  this  nature. 

Charcoal  well  made  has  neither  fmell  nor  tafte  ;  and  it  is  one 
of  the  moil  indecompofable  fubftances  we  are  acquainted 
with. 

When  dry,  it  is  not  changed  by  diftillation  in  clofe  vcfTels. 
But,  when  moift,  it  affords  hydrogenous  gas  and  carbonick  acid  ; 
which  proves  the  decompofition  of  the  water,  and  the  combina- 
tion of  one  of  its  principles  with  the  charcoal,  while  the  other 
is  dilTipated.  By  fucceifively  moiftening  and  diftilling  charcoal, 
it  may  be  totally  deftroyed. 

Charcoal  combines  with  oxigene,  and  forms  the  carbonick 
acid  ;  but  this  combination  does  not  take  place  unlefs  their  ac- 
tion be  aflifted  by  heat.     The  charcoal  which  burns  in  a  chaf- 


Properties  of  Charcoal,  ^m 

fing-difti  exhibits  this  refult ;  and  we  perceive  two  very  im- 
mediate efFe£ts  in  this  operation  : — i.  A  difengagement  of  heat 
afforded  by  the  tranfition  of  the  oxigenous  gas  to  the  concrete 
ftate.  2.  A  production  of  carbonick  acid  :  it  is  the  formation 
of  this  acid  gas  which  renders  it  dangerous  to  burn  charcoal  in 
places  where  the  current  of  air  is  not  fufficiently  rapid  to  carry 
off  the  carbonick  acid  as  it  is  formed. 

Well-made  charcoal  does  not  change  by  boiling  in  water.  In 
procefs  of  time  it  gives  a  flight  reddifh  tinge  to  that  fluid,  which 
arifes  from  the  folution  of  the  coaly  refidue  of  the  oils  of  the 
vegetable  mixed  with  the  coaly  refidue  of  the  fibre. 

If  the  fulphurick  acid  be  digefted  upon  charcoal,  it  is  decom- 
pofed ;  and  affords  carbonick  acid,  fulphureous  acid,  and  ful- 
phur. 

The  nitrick  acid,  when  concentrated,  is  decompofed  with 
much  greater  rapidity  \  for  if  it  be  poured  upon  very  dry  pow- 
der of  charcoal,  it  fets  it  on  fire.  This  inflammation  may  be  fa- 
cilitated by  heating  the  charcoal  or  the  acid.  If  the  fluid  which 
arifes  in  this  experiment  be  colle£led,  it  is  found  to  be  carbonick 
acid,  nitrous  gas,  and  nitrick  acid.  M.  Proud  has  obferved,  that 
■when  the  acid  is  poured  into  the  middle  of  the  charcoal,  it  does 
not  take  fire  ;  but  that  this  effect  immediately  fucceeds  if  the 
acid  be  fuffered  to  flow  beneath  the  coal.  It  may  even  be  in- 
flamed by  throwing  it  upon  the  nitrick  acid  flightly  heated. 

If  weak  nitrick  acid  be  digefted  upon  charcoal,  it  diffolves  it, 
aflumes  a  red  colour,  becomes  pafty,  and  acquires  a  bitter  difa- 
greeable  tafte. 

Charcoal,  mixed  with  the  fulphurick  and  nitrick  falts,  decom<f 
pofes  them  ;  when  combined  with  oxides,  it  revives  the  metals. 
All  thefe  effects  depend  on  its  very  great  aflSnity  with  the  oxi- 
gene  contained  in  thefe  bodies.  It  is  ufed  to  facilitate  the  de- 
compofition  of  falt-petre  in  fome  cafes,  as  in  the  compofition  of 
gun-powder,  the  black  flux,  &c. 

Rouelle  has  obferved  that  the  fixed  alkali  diffolves  a  good 
quantity  of  charcoal  by  fufion.  The  fame  chcmift  has  difcov- 
ered  that  the  fulphure  of  alkali  diffolves  it  in  the  humid  as  well 
as  the  dry  way. 

Charcoal  is  likewife  capable  of  combining  with  metals.  It 
combines  with  iron  in  its  firft  fufion,  and  mixes  with  it  likewife 
in  the  cementation  by  which  fteel  is  formed.  When  combined 
with  iron  in  a  fmall  proportion  of  the  metal,  it  conftitutes  plum- 
bago. It  is  likewife  capable  of  combining  with  tin  by  cementa- 
tion ;  to  which  metal  it  gives  a  brilliancy  and  hardnefs,  as  I  fin4 
by  experiment. 


5»4  A8'ion  of  Water  on  Vegetables. 

CHAPTER    II. 

Concerning  the  A<5lion  of  Water  fingly  to  Vegetables. 

WE  may  confider  the  a£lion  of  water  upon  vegetables  in  two 
very  different  points  of  view.  Either  the  chemift  applies  this 
fluid  to  the  plant  itfelf,  to  extract  and  feparate  the  juices  from 
^;the  ligneous  part :  or  elfe  the  plant  itfelf,  being  immerfed  in 
'this  fluid,  is  from  this  time  delivered  to  its  fingle  adlion  ;  and  in 
that  fituation  becomes  gradually  changed  and  decompofed  in  a 
peculiar  manner.  In  thefe  two  cafes,  the  products  of  the  opera- 
tions are  very  different.  In  the  firlt,  the  ligneous  texture  re- 
mains untouched,  and  the  juices  which  are  feparated  remain  un- 
changed in  the  fluid  :  in  the  fecond,  more  efpecially  when  ve- 
getables ferment  in  heaps,  the  nature  of  the  juices  is  partly 
changed,  but  the  oils  and  refins  remain  confounded  with  the  lig- 
neous tiffue ;  fo  that  the  refult  is  a  mafs  in  which  the  diforgan- 
ized  vegetable  is  feen  in  a  ftate  of  mixture  and  confufion  of  the 
various  principles  which  compofe  it. 

The  chemift  applies  water  to  vegetables,  to  extract  their  jui- 
ces, according  to  two  methods,  which  conftitute  infufion  and 
cieco£lion. 

Infufion  is  performed  by  pouring  upon  a  vegetable  a  fufficient 
quantity  of  hot  water  to  diffolve  all  its  principles.  The  temper- 
ature of  the  water  muft  be  varied  according  to  the  nature  of  the 
plant.  If  this  texture  be  delicate,  or  the  aroma  very  fugacious, 
the  water  mult  be  flightly  heated  ;  but  boiling  water  may  be  ufed 
when  the  texture  is  hard  and  folid,  and  more  efpecially  when 
the  plant  has  no  fmell. 

Decodl:ion,  which  coiififts  in  boiling  water  with  the  vegeta- 
ble, ought  not  to  be  employed  but  with  hard  and  inodorous 
plants.  This  method  is  reje£l:ed  by  many  chemifts  ;  becaufe 
they  affirm  that,  by  thus  tormenting  the  plant,  a  conflderable 
quantity  of  fihrous  matter  becomes  mixed  with  the  juices.  De- 
coction is  generally  banifhed  from  the  treatment  of  odorant 
plants,  becaufe  it  diflipates  the  volatile  oil  and  aroma.  The  de- 
co(flion  ufed  in  our  kitchens  to  prepare  leguminous  plants  for 
food,  has  the  inconvenience  of  extracting  all  the  nutritive  parts, 
and  leaving  only  the  fibrous  parenchyma.  Hence  arifes  the  ad- 
vantage of  the  American  pot  or  boiler,  in  which  the  garden-fluff 
is  boiled  by  fimple  vapour,  and  confequently  the  nutritive  prin- 
ciple remains  in  the  vegetable ;  to  which  advantage  we  may  add  / 
that  of  ufi  ng  any  water  whatever,  becaufe  the  fleam  alone  is  ap- 
plied to  the  intended  purpofe. 


Vegetable  ExtraEls.  505 

But  the  infufion,  dcco«Elion,  and  clarification  of  juices,  is  not 
left  to  the  choice  of  the  chemift,  when  it  is  required  to  prepare 
any  medicine ;  for  thefe  methods  produce  furprifmg  varieties  in 
the  virtue  of  remedies.  Thus,  for  example,  according  to  Storck, 
the  concentrated  juice  of  hemlock  has  no  good  qualities  unlefs  it 
be  evaporated  without  being  clarified. 

In  treating  juniper  berries  by  infufion,  and  evaporation  on 
a  water  bath  to  the  confidence  of  honey,  an  aromatick  extra<St 
is  obtained,  of  a  faccharine  colour  :  the  deco£lion  of  the  fame 
berries  affords  a  lefs  fragrant  and  lefs  refinous  extra£l:,  becauf© 
the  refin  feparates  from  the  oil,  and  falls  down. 

The  extra£t  of  grapes  which  is  called  refi7ie  in  France,  and 
mcft  fweetmeats,  are  prepared  in  this  way. 

Extracts  are  prepared  in  the  large  way  for  fale  by  the  aflifl:- 
ance  of  water.  We  fliall  confine  ourfelves  to  fpcak  of  two  on- 
ly, the  juice  of  liquorice  and  of  cachou.  The  firft  will  afford 
an  example  of  deco6lion,  and  the  fecond  of  infufion. 

The  extra(fl  of  liquorice  is  prepared  in  Spain  by  decottion 
of  the  flirub  of  the  fame  name.  This  plant  grows  abundantly 
near  our  ponds  -,  and  we  might  at  a  fmall  expenfe  avail  ourfelves 
of  this  fpecics  of  induftry  :  I  have  afcertained  that  a  pound  of 
this  root  affords  two  or  three  ounces  of  good  extradt.  The 
apothecaries  afterwards  [prepare  It  in  various  ways  for  their 
feveral  purpofes,  and  to  render  its  ufe  more  convenient  and  a- 
greeable. 

The  cachou  is  extra6led  in  the  Eaft-Indies  from  an  infufion 
of  the  feeds  of  a  kind  of  palm.  While  the  feed  is  yet  green,  it 
is  cut,  infufed  in  hot  water  ;  and  this  infufion  is  evaporated  to 
the  confiftence  of  an  extract,  which  is  afterwards  made  into 
lumps,  and  dried  in  the  fun.  M.  de  Juffieu  communicated  to 
tlie  Academy,  in  the  year  1720,  remarks  by  which  he  afcertains 
that  the  differences  in  the  feveral  kinds  of  cachou  arife  from  the 
various  degrees  of  maturity  in  the  feeds,  and<he  greater  or  lefs 
quicknefs  with  which  the  extraft  is  dried. 

The  cachou  of  commerce  is  ufually  impure;  but  It  maybe 
cleared  of  its  impurities  by  diffolving,  filtering,  and  evaporating 
It  fevtral  times. 

The  tafte  of  cachou  is  bitter  and  aftringent.  It  diffolves  very 
well  in  the  mouth,  and  is  ufed  as  a  reftorative  for  weak  flom- 
achs  :  it  is  made  into  comfits  by  the  addition  of  three  parts  of 
fugar,  and  a  fufficient  quantity  of  gum  adragant. 

When  vegetables   are  immerfed  in  water,    their  texture  be- 
\ comes  relaxed  ;    all  the  folubie  principles  are  carried  off;    and 
there  remains  only  the  fibrous  part    diforganized,  and  impreg- 
nate d  with  vegetable  oil,    altered  and  hardened  by  the  readlion 
3...CL 


5«^  Fcrmaiton  of  Pit-CoaL 

of  other  principles.  This  tranfition  may  be  very  well  obfervccf 
in  marfhes,  where  plants  grow  and  periih  in  great  numbers, 
forming  mud  by  their  decompofition.  Thefe  flrata  of  decom- 
pofed  vegetables,  when  taken  out  of  the  water  and  dried,  may  be 
ufed  as  the  material  of  combuftion.  The  fmell  is  unwholefome  ; 
but  in  (hops,  or  places  where  the  chimneys  draw  well,  this  com- 
buftible  may  be  ufed. 

Vegetables  have  been  confidered  as  the  caufe  of  the  forma- 
tion of  pit-coal ;  but  a  few  forefbs  being  buried  in  the  earth, 
are  not  fufficient  to  form  the  mountains  of  coal  which  exifl:  in 
its  bowels.  A  greater  caufe,  more  proportioned  to  the  magni- 
tude of  the  efFeft,  is  required  ;  and  we  find  it  only  in  that  pro- 
digious quantity  of  vegetables  which  grow  in  the  feas,  and  is  flill 
increafed  by  the  immenfe  mafs  of  thofe  which  are  carried  down 
by  rivers.  Thefe  vegetables,  carried  away  by  the  currents,  are 
agitated,  heaped  together,  and  broken  by  the  waves  ;  and  after- 
wards become  covered  with  ftrata  of  argillaceous  or  calcareous 
earth,  and  are  decompofed.  It  is  eafier  to  conceive  how  thefe 
maffes  of  vegetables  may  form  flrata  of  coal,  than  thafthe  re- 
mains of  {hells  fliould  form  the  greater  part  of  the  globe. 

The  direct  pjoofs  which  may  be  given  of  the  truth  of  this 
theory  are — 

1.  The  prefence  of  vegetables  in  coal  mines.  The  bamboo 
and  bannana  trees  are  found  in  the  coal  of  Alais.  It  is  common 
to  find  terreftrial  vegetables  confounded  with  marine  plants. 

2.  The  prints  of  fhells  and  of  fifh  are  likcwife,  found  in  the 
ftrata  of  coal,  and  not  unfrequently  (hells  themfelves.  The  pit- 
coal  of  Orfan  and  that  of  Saint  Efprit  contain  a  prodigious  num- 
ber. 

3.  It  is  evidently  feen,  by  the  nature  of  the  mountains  which 
contain  charcoal,  that  then*  formation  has '  been  fubmarine  ;  for 
they  all  confift  either  of  fchiftus,  or  grit,  or  limeftone.  The 
fecondary  fchiftus  is  a  kind  of  coal  in  which  the  earthy  principle 
predominates  over  the  bituminous.  Sometimes  even  this  fchif- 
tus is  combuflible,  as  is  feen  in  that  of  St.  George  near  Milhaud. 
The  texture  of  the  vegetables,  and  the  imprelfion  of  fifli,  are  ve- 
ry well  preferved  in  the  fchiftus.  The  origin  of  the  fchiftus  is 
therefore  fubmarine  ;  and  confequently  fo  likev/ife  muft  be  the 
origin  of  the  coal  diftributed  in  flrata  through  its  thicknefs. 

The  grit -ftone  confifls  of  fand  heaped  together,  carried  into 
the  fea  by  the  rivers,  and  thrown  up  again  ft  the  fhores  by  the 
waves.  The  ftrata  of  bitumen  which  are  found  in  thefe  can*- 
not  therefore  but  come  from  the  fea. 

Calcareous  earth  rarely  contains  ftrata  of  coal,  but  is  merely 
impregnated  with  it,  as  at  St.  Ambroife,  at  Servas,  &c.  where 
the  bitunven  forms  a  ceracnt  with  the  calcareous  earth. 


Formation  of  PiuCoal,  507 


Concerning  ?it-CoaI. 

Pit-coal  is  ufually  found  in  ftrata  in  the  earth,  almofl:  always 
in  mountains  of  fchiftus  or  grit.  It  is  the  property  of  coal  to 
♦burn  with  flame,   and  the  emilFion  of  much  fmoke. 

The  fecondary  fchiftus  is  the  bafis  oi.  all  pit-coal,  and  the 
, quality  of  the  ccal  moflly  depends  upon  the  proportion  of  this 
rbafis.  When  the  fchiftus  predominates,  the  coal  is  heavy  and 
leaves  a  very  abundant  earthy  refidue  after  its  combuftion. 
This  kind  of  coal  is  veined  internally  with  flat  pieces,  or  rather 
leparate  mafles,  of  fchiftus  nearly  pure,  which  we  CtiW  Jiches, 

As  the  formation  of  the  pyrites,  as  well  as  that  of  coal,  arifes 
from  the  decompofition  of  vegetable  and  animal  fubftances,  all 
pit -coal  is  more  or  lels  pyritous;  fo  that  we  may  confider  pit- 
coal  as  a  mixture  of  pyrites,  fchiftus,  and  bitumen.  The  differ- 
ent qualities  of  coal  arife  therefore  from  the  difference  in  the 
proportions  of  thefe  principles. 

When  the  pyrites  is  very  abundant,  the  coal  exhibits  yellow 
veins  of  the  mineral,  which  are  decompofed  as  foon  as  they 
come  in  contact  with  the  air  ;  and  form  an  etlorefcence  of  ful- 
phate  of  magnefia,  of  iron,  of  alumine,  &c. 

When  pyritous  coal  is  itt  on  fire^  it  emits  an  infupportable 
fmell  of  fulplmr ;  but  when  the  combuftion  is  infenfible,  in- 
flammation is  frequently  produced  by  the  decompofition  of  the 
pyrites  ;  and  it  is  this  which  occafions  the  inflammation  of  fev- 
eral  veins  of  coal.  There  are  veins  of  coal  on  fire  at  St. 
Etienne  in  Forez,  at  Cramfac  in  Rouergue,  at  Roquecremade  in 
the  diocefe  of  Beziers  \  and  it  is  not  rare  to  fee  the  fire  dcftroy 
confiderable  maffes  of  pyritous  coal,  when  the  decompofition  is 
favoured  by  the  concurrence  of  air  and  water.  If  the  inflam- 
mation be  excited  in  more  confiderable  maffes  of  bitumen,  the 
effects  are  then  more  ftriking  j  and  it  is  to  a  caufe  of  this  na- 
ture that  we  ought  to  refer  the  origin  and  effect  of  volcanos. 

When  the  fchiftus  or  flaty  principle  predominates  in  coals, 
they  are  then  of  a  bad  quality,  becaufe  their  earthy  refidue  is 
more  confiderable. 

The  beft  coal  is  that  in  which  the  bituminous  principle  is  the 
moft  abundant,  and  exempt  from  all  impurity.  This  coal  fwells 
up  when  it  burns,  and  the  fragments  adhere  together  :  It  is 
more  particularly  upon  this  quality  that  the  pradlice  of  the  op- 
eration called  defulpharating  or  purifying  of  co'al  depends. 
This  operation  is  analogous  to  that  in  which  wood  is  converted 
into  charcoal.  In  the  defulphuration,  pyramids  are  made, 
which  are  fet  on  fire  at  the  centre.     When  the  heat  has  ftron^- 


5o8  Properties  of   Pit-Coal 

ly  penetrated  the  mafs,  and  the  flame  ilTues  out  of  the  fides,  it  is 
then  covered  with'  nioift  earth  ;  the  combuftion  is  fufFocated, 
the  bitumen  is  diflfipated  in  fmcke,  and  there  remains  only  a  light 
fpungycoal,  which  attradls  the  air  and  humidity,  and  exhibits 
the  fame  phenomena  in  its  combuftion  as  the  coal  of  wood. 
When  it  is  well  made,  it  gives  neither  flame  or  fmoke  ;  but  it 
produces  a  ftronger  heat  than  that  of  an  equal  mafs  of  native 
coal.  This  operation  received  the  name  of  defulpharating  (de- 
foufrage)  from  a  notion  that  the  coal  was  by  this  means  deprived 
of  its  fulphur  ;  but  it  has  been  proved  that  all  coals  which  are 
capable  of  this  operation  contain  fcarcely  any  fulphur. 

It  was  for  a  long  time  fuppofed  that  the  fmell  of  pit-coal  was 
unwholefome  ;  but  the  contrary  is  now  proved.  Mr.  Vencl  has 
made  many  experiments  on  this  fubjecfb,  and  is  convinced  that 
neither  man  nor  animals  are  incommoded  by  this  vapour.  Mr. 
Hoffman  relates  that  diforders  of  the  lungs  are  unknown  in  the 
villages  of  Germany,  where  this  combuflible  only  is  ufed.  I 
think  that  coal  of  a  good  quality  does  not  emit  any  dangerous 
vapour  J  but  when  it  is  pyritous  its  fmell  cannot  but  be  hurtful. 

The  ufe  of  coal  is  generally  applicable  to  the  arts  ;  and  na- 
ture appears  to  have  concealed  thefe  magazines  of  combultible 
matter,  to  give  us  time  to  repair  our  exhaufted  forefts.  Thefe 
mines  are  very  abundant  and  numerous  in  the  kingdom  of 
France.  Oar  province  contains  many,  and  we  have  more  than 
twenty  which  are  in  full  work.  Pit  coal  is  applied  in  England 
even  to  domeftick  ufes,  and  this  part  of  mineralogy  is  very 
much  cultivated  in  that  kingdom.  Individuals  have  there  un- 
dertaken the  moft  confiderable  enterprizes  in  this  w^ay.  The 
Duke  of  Bridgewater  has  m.ade  a  canal,  at  Bridgewater,  two 
thoufand  fiv6  hundred  toifes  in  length,  to  facilitate  the  working 
of  the  coal  mines  in  Lancafhire.  It  ccit  five  millions  of  livres  : 
part  of  it  is  carried  under  a  mountain  ;  and  it  pafles  fucceffively 
under  as  well  as  over  rivers  and  highv^^ays.  In  our  province  we 
are  in  want  of  roads  only  for  the  tranfportation  of  our  coal ;  and 
Languedoc  has  not  had  the  fpirit  to  perform  a  work  which  a 
private  individual  has  executed  in  England. 

In  Scotland,  Lord  Dundonald  has  ereded  furnaces  in  which 
the  bitumen  is  difengaged  from  coal  ;  and  the  vapours  are  re- 
ceived and  condenfed  in  chambers,  over  which  he  has  caufed 
a  river  to  flow  for  the  purpofe  of  cooling  them.  Th'efe  con- 
denfed vapours  fupplyjUie  Englifli  navy  with  as  much  tar  as  it 
requires.  Becher  in  his  work  entitled  <«  Foolifli  Wifdom,  or 
Wife  Foily,"  printed  at  Fvanckfort  in  1683,  affirms  that  he  fuc- 
ceedediri  appropriating  the  bad  turf  of  Holland,  and  the  bad 
coal  of  England;  to  the  common  ufes,     He  adds  that  he  obtaia-i 


Mineral  Comhujiihks.  ^%^ 

cd  tar  fuperiour  to  that  of  Sweden  by  a  procefs  fimilar  to  that 
of  the  Swedes.  He  aflirms  that  he  had  made  this  known  in  En- 
gland, and  (hown  it  to  the  king. 

Mr.  Faujus  has  carried  the  procefs  of  the  Scotch  nobleman  in- 
to execution  at  Paris.  The  whole  confifts  in  fetting  fire  to  the 
coal,and  extinguiihing  it  at  the  proper  time,  that  the  vapour  may 
pafs  into  chambers  containing  water  for  the  purpofe  of  conden- 
fing  them.     This  tar  appeared  to  be  fuperiour  to   that  of  wood. 

Pit  coal  likewife  affords  ammoniack  by  diftillation,  which  is 
diffolved  in  water,  while  the  oil  floats  above. 

Vv'hen  coal  is  deprived  by  combuition  of  all  the  oil  and  other 
volatile  principles,  the  earthy  refidue  contains  the  fulphatcs  of 
alumine,  iron,  magnefia,  lime,  &c.  Thefe  falts  are  all  formed 
•when  the  combultion  is  flow  ;  but  when  it  is  rapid  the  fulphur 
is  diflipated,  and  there  remain  only  the  aluminous,  magnefian, 
calcareous,  and  other  earths.  The  alumine  moft  commonly 
predominates. 

Naptha,  petroleum,  mineral  pitch,  and  afphaltes,  are  only 
flight  modifications  of  the  bituminous  oil  fo  abundant  in  pit  coal. 
This  oil,  which  the  fimpleheat  of  the  decompofition  of  the  py- 
rites is  fufl[icient  to  difengage  from  the  coal,  receives  other  mod- 
ifications by  the  impreflion  of  the  external  air. 

Petroleum,  or  the  oil  petrol,  isthe  firft  alteration.  This  oil 
is  found  near  volcanos,  in  the  vicinity  of  coal  mines,  &c.  We 
are  acquainted  with  feveral  fprings  of  this  petroleum.  There 
is  one  at  Gabian  in  the  diocele  of  Beziers.  It  is  carried  out  by 
the  water  of  a  fpring  which  iflues  from  the  lower  pare  of  a 
mountain  whofe  fummit  is  volcanized. 

The  fmell  of  petroleum  is  difagreeable  :  its  colour  is  reddifli  ; 
but  it  may  be  rendered  clear  by  didilling  it  from  the  clay  of 
Murviel. 

Naptha  is  merely  a  variety  of  petroleum. 

Near  Derbens,  on  the  Cafpian  Sea,  there  are  fprings  of  nap- 
tha, which  Kempfer  vifited  about  a  century  ago,  and  of  which 
he  has  left  a  defcription. 

There  is  a  place  known  by  the  name  of  the  Perpetual  Fire, 
where  the  fire  burns  without  ceafing.  The  Indians  do  not  at- 
tribute the  origin  of  this  inextinguifhable  fire  to  naptha  j  but 
they  maintain  that  God  has  confined  the  Devil  in  this  place  to 
deliver  man  from  him.  They  go  in  pilgrimage  thither,  and 
make  their  prayers  to  God  that  he  will  apt  fufl^er  this  enemy  of 
mankind  to  efcape. 

The  earth  impregnated  with  naptha  is  calcareous,  and  efit;r- 
vefces  v^ith  acids  \  ir  takes  fire  by  the  contad:  of  any  ignited 
body  whatever. 


§im  Mineral.  Comhujlibles. 

This  perpetual  fire  is  of  great  ufe  to  the  inhabitants  of  Baku. 
They  pare  oiF  the  furface  of  this  burning  foil,  upon  which  they* 
make  a  heap  of  lime  ftones,  and  cover  it  with  the  earth  pared 
off ;    and  in  two  or  three  days  the  lime  is  made. 

The  inhabitants  of  the  village  of  Frogann  repair  to  this  place 
to  cook  their  provifions. 

The  Indians  afiemble  from  all  parts  to  adore  the  Eternal  Be- 
ing in  this  place.  Several  temples  were  built,  one  of  which  is 
lliii  in  exiilence.  Near  the  altar  there  is  a  tube  inferted  in  the 
earth,  two  or  three  feet  in  length ,  out  of  which  ifiues  a  blue 
jlame,  mixed  with  red.  The  Indians  proftrate  themfelves  be- 
fore this  tube,  and  put  themfelves  into  attitudes  which  are  ex- 
ceedingly flrange  and  painful. 

Mr.  Omelin  obferves  that  two  kinds  of  naptha  arediftinguifh- 
€d  in  this  country  ;  the  one  tranfparent  and  yellow,  which  is 
found  in  a  well.  This  well  is  covered  with  ftones  fmeared  with 
a  cement  of  fat  earth,  in  which  the  name  of  Kan  is  engraved  ; 
and  no  one  is  permitted  to  break  this  fealed  covering  but  thofe 
who  are  deputed  from  the  Kan. 

Mineral  pitch  is  likewife  a  modification  of  petroleum.  It  is 
found  in  Auvergne,  at  a  place  called  Puits  de  Lapege,  near  A- 
lais,  in  an  extent  of  feveral  leagues,  which  comprehends  Servas, 
Saint  Ambroix,  &c. 

The  calcareous  (tone  is  impregnated  with  a  bitumen  which  is 
fof  tened  by  the  heat  of  fummer,  when  it  flows  from  the  rocks, 
and  forms  a  very  beautiful  ltala£f  ites.  It  forms  mafles  in  the 
fields,  and  impedes  the  pafiage  of  carriages  :  the  peafants  ufc 
it  to  mark  their  fiieep.  This  ftone  emits  an  abominable  fmell 
when  rubbed.  The  epifcopal  palace  of  Alais  was  paved  v/iih  it 
in  the  time  of  Mr.  Davejan  ;  but  it  became  necefiary  to  fubfti- 
tute  other  ftone  in  its  Head.  It  is  aflerted  that  mineral  pitch  was 
uicA  to  cement  the  walls  of  Babylon. 

Afphaltes,  or  bitumen  Judaicum,  is  black,  brilliant,  ponder- 
ous, and  very  brittle. 

It  emits  a  fmell  by  friclion  ;  and  is  found  floating  on  the  wa- 
ter of  the  lake  Afphaltites,  or  the  Dead  Sea. 

The  af^^haltes  of  commerce  is  extradkd  from  the  mines  of 
Annemore,  and  more  particularly  in  the  principality  of  Neufcha- 
tel.  Mr.  Pallas  found  fprings  of  afphaltes  on  the  banks  of  the 
Sock,  in  PrufQa. 

Moft  naturaliilscQiifider  it  as  ^amber  decompofcd  by  fire.  Af- 
phaltes liquefies  on  tlie  fire,  fvvells  up,  and  affords  flame,  with 
an  acrid  difagreeable  fmoke. 

By  diftiilation  it  affords  an  oil  refembling  petroleum.  The 
Indians  and  Arabs  ufe  if  inftead  of  tar,  and  it  is  a  component 
part  of  the  varnifh  of  the   Chinefe. 


ProperiteS)  ^c,  of  Amher»  5  H 

Yellow  amber,  karabe,  cr  the  eledlron  of  the  ancients,  is  ia 
yellow  or  brown  pieces,  tranfparent  or  opaque,  capable  of  a  pol- 
ifh,  becoming  eledrick  by  fridion,  &c. 
It  is  friable  and  brittle. 

There  is  no  fubftance  on  which  the  imagination  of  poets    has 

[been  more  exerrifed  than  this.     Sophocles  had  affirmed  that  it 

ras  formed  in  India  by  the  tears  of  the  fillers  of  Meleager,  chan- 

red  into  birds*  and  deploring  the  fate  of  their  brother  -,  but  one 

fef  the  moft  interefting  fabulous  origins  which  have  been  attrib- 

[iited  to  it,  is  afforded  by  the  fable  of  Phaeton  burning  the  hea- 

[irens  and  the  earth,  and  precipitated  by  the  thunder  of  Jove  in- 

thc  waters  of  Eridanus.     His  fillers  are   defcribed  weeping  ; 

^and  the  precious  tears  fell  into  the  waters  without  mixing  with 

^fhem,  became  folid  without  lofmg  their  tranfparency,  and  were 

|t:onverted  into  the  yellow  amber  fo  highly  valued   by  the   an- 

jients. — See  Bailly.  1 

Amber  poflefles  lefs  coaly  matter  than  any  other  bitumen. 

It  is  frequently  found  difperfed  over  ftrata  of  pyritous  earthy 

[and  covered  with  a  (Iratum  of  wood,  abounding  with  a  blackifii 

)iiuminous  matter. 

It  is  found  floating  in  the  Baltick  Sea,  on  the  coall  of  Ducal 
Vullia  ;  it  is  alfo  found  near  Siftreron  in  Provence. 

No  other  chemical  ufe  was  for  a  long  time  made  of  amber, 
than  to  form  compofitions  for  medicine  and  the  arts.  We  are 
Indebted  to  Neumann,  Bourdclin,  and  Pott  for  a  tolerably  accu- 
rate analyfis  of  this  bitumen.  The  two  conilituent  principles  ex- 
libited  in  the  analyfis  of  amber,  are  the  fait  of  amber,  or  fuccin- 
:k  acid,  and  a  bitumous  oil. 

To  extra£l  the  fuccinick  acid,  the  amber  is  broken  into  fmall 
)ieces,  which  are  put  into  a  refort,  and  diRilled  with  a  fuitable  ap- 
laratus  upon  a  fand  bath.  When  the  fire  is  carefully  managed, 
the  products  are — i.  Aninfipid  phlegm,  2.  Phlegm  holding  a 
fmall  portion  of  acid  in  fglution.  3.  A  concrete  acid  fait, 
'hich  attaches  itfelf  to  the  neck  of  the  retort.  4.  A  brown  and 
thick  oil,  which  has  an  acid  fmell. 

The  concrete  fait  always  retains  a  portion  of  oil*  in  its  firfl 
liflillaticn.  Scheffer,  in  his  LefTuns  of  Chemiilry,  propofes  to 
liftil  it  with  fand  j  Bergmann  with  white  clay  -,  Poit  advifes  fo- 
lution  in  water,  and  filtration  through  white  cotton  ;  after  which 
the  fluid  is  to  be  evaporated,  and  is  found  to  be  deprived  of  the 
>il,  which  remains  on  the  cotton.  Spieknsnn,  after  Pott,  pro- 
jofes  to  diltil  it  with  the  muriatick  acid  'it  then  fubliaies  white 
and  pure.     Bourdelin  clears  it  of  its  oil  by  detonation  with  ni- 

*  Acide  in  the  original ;  doubtlefs  by  over  fight,    T. 


SI? 


Volcanoes, 


tre.     This  fait  is  prepared  in  the  large  way  at  Koningfbergi 
where  the  (havings  and  chips  of  amber  are  dillUled. 

The  fuccinick  acid  has  a  penetrating  tafte,  and  reddens  the 
tinQure  of  turnfole.  Twenty-four  parts  of  cold  water,  and 
two  of  boiling  water,  diiTolve  one  of  this  acid.  If  a  faturated 
folution  of  this  fait  be  evaporated,  it  cryftallizes  in  triangular 
prifms,  whofe  points  arc  t>-uncated. 

Mr.  de  Morveau  obferves  that  its  affinities  are  barytes,  lime, 
alkalis,  magnefia,  &c. 

The  oil  of  amber  has  an  agreeable  fmell :  it  may  be  deprived 
of  its  colour  by  diftiilation  from  white  clay.  Rouelle  diftilled 
it  with  water.  When  mixed  with  ammoniack  it  forms  a  liquid 
foap,  known  by  the  name  of  Eau  de  Luce. 

To  make  eau  de  luce,  I  difiblve  Punick  wax  in  alcohol,  with' 
a  fmall  quantity  of  oil  of  amber ;  and  on  this  I  pour  the  pure 
volatile  alkali. 

Alcohol  attacks  amber,  and  acquires  a  yellow  colour.  HofF-^ 
mann  prepares  this  tincture  by  mixing  the  fpirit  of  wine  with 
an  alkali. 

The  medical  ufe  of  amber  confifts  in  burning  it,  and  receiv- 
ing the  vapour  on  the  difeafed  part.  Thefe  vapours  are  llrength- 
ening,  and  remove  obftruclions.  The  oil  of  amber  is  applied 
to  the  fame  ufe.  A  fyrup  of  amber  is  made  with  the  fpirit  of 
amber  and  opium,  vidiich  is  ufed  to  advantage  as  a  fedative  ano- 
dyne medicine.  The  fined  pieces  of  amber  are  ufed  to  make 
toys.  Wallerius  afiirms  that  the  mod  tranfparent  pie'ces  may  be 
ufed  to  make  mirrors,  prifms,  &c.  It  is  faid  that  the  king  of 
Pruffia  has  a  burning  mirror*  of  amber  one  foot  in  diameter  ; 
and  that  there  is  a  column  of  amber  in  the  cabinet  of  the  Duke 
of  Florence  ten  feet  high,  and  of  a  very  fine  luftre. 

Concerning  Volcanos. 

The  combuftion  of  thofe  enormous  maiTes  of  bitumen  which 
are  depofited  in  the  bowels  of  the  earth,  produces  volcanos. 
They  owe  their  origin  more  efpecially  to  the  ftrata  of  pyritous 
coal.  The  decompofition  of  water  upon  the  pyrites  determines 
the  heat,  and  the  production  of  a  great  quantity  of  hydrogen- 
ous gas,  which  exerts  itfelf  againft  the  furrounding  obllacies, 
and  at  length  breaks  them.  This  eifefl  is  the  chief  (jaufe  of 
earthquakes  ;  but  when  the  concourfe  of  air  facilitates  the  com- 
% 

'^  So  in  the  original  ;  but  the  matter  as  well  as  the  properties  of  this 
lubflance  put  it  out  of  doubt  tliat  it  fiiouid  be  lens.    T. 


Volcanick  Phenomena. 


sa 


buftion  of  the  bitumen  and  the  hydrogenous  gas,  the  flame  is 
feen  to  ifTue  out  of  the  chimneys  or  vents  which  are  made  :  and 
this  occafions  the  fire  of  volcanos. 

There  are  many  volcanos  (till  in  an  adive  flate  on  our  globe, 
independent  of  thofe  of  Italy,  which  are  the  mod  known.  The 
abbe  Chappe  has  defcribcd  three  burning  in  Siberia.  Anderfon 
and  Von  froil  have  defcribed  thofe  of  Iceland.  Afia  and  Afri- 
ca contain  feveral :  and  we  find  the  remains  of  thefe  fires  or 
volcanick  produ6tsin  all  parts  of  the  globe. 

Naturalilts  inform  us  that  all  the  fouthern  idands  have  been 
volcanizcd  ;  and  they  are  feen  daily  to  be  formed  by  the  action 
of  thefe  fubterraneous  fires.  The  traces  of  fire  exid  even  im- 
mediately around  us.  The  fingle  province  of  Languedoc  con- 
tains more  extinct  volcanos  than  twenty  years  ago  were  known 
to  exill  through  all  Europe.  The  black  colour  of  the  (tones, 
their  fpungy  texture,  the  other  produdts  of  fire,  and  the  identi- 
ty of  thefe  fubftances  with  thofe  of  the  volcanos  at  prefent 
burning,  are  all  in  favour  of  the  opinion  that  their  origin  was 
the  fame.* 

*  A  volcano  was  announced  and  defcribed  to  be  burning  in  Languedoc, 
refpcdlng  which  it  is  necefiliry  to  give  fome  elucidition.  This  pretended 
volcano  is  known  by  the  name  of  the  Phofphorus  of  Venejan. 

Venejan  is  a  village  fittiated  at  the  diitance  of  a  quarter  of  a  league 
from  the  high  road  between  St.  Efprit  and  Bagnols.  From  time  immem- 
orial at  the  return  of  fpring,  a  fire  was  feen  from  the  highroad,  which in- 
creafed  daring  the  fummer,  was  gradually  extinguilhed  in  autiiftm,  and 
wasvifible  onlyin  the  night.  Several  perfons  had  at  various  times  directed 
their  courle  from  the  high  road,  in  a  right  line  towards  VenejanJ  to  verify 
the  fa(^  upon  the  fpot  ;  but  the  neceflity  of  defcending  into  a  deep  Valley 
before  they  could  arrive  thither,  occafioned  them  to  lofc  light  of  the  fire  ; 
and  on  then' arrival  at  Venejan  noappearance  was  feen  in  the  leall  refembling 
the  fire  of  a  volcano.  ^  Mr.  dc  Genflane  defcribes  this  phenomenon,  and 
compares  it  to  the  flafliing  of  a  llrong  aurora  borealis  :  he  even  fays  thac 
the  country  is  volcanick.  Hift.  Mat.  du  Languedoc,  Diocefe  de'Uzes. — 
At  length,  in  the  courfe  of  the  lalt  four  or  live  years,  it  was  obferved  that 
thefe  fires  were  multiplied  in  tiie  fpring;  and  that,  inllead  of  one,  ther« 
were  three.  Certain  Philofophers  of  Hagnols  undertook  the  proje^T:  of  ex- 
a  nining  this  phenomenon  more  cloffly,  and  for  this  purpofe  they  repaired 
to  a  fpot  between  the  high  road  ana  Tencjan  armed  with  torches,  fpeaking 
trumpets,  and  every  orher  implemeni  which  they  conceived  to  be  neceffary 
for  making  their  obfervk'tions.  At  midnight,  four  or  five  of  the  party 
were  deputed  and  direcfled  tov/ards  the  fire  ;  and  thofe  who  remained 
behind  dircifted  them  conllantly  \\\  their  way  by  means  of  their  fpeaking 
trumpets.  -  They  at  laH:  arrived  at  the  village,  where  tli£y  found  three 
groupes  of  women  windingfilk  in  x[\q.  middle  of  the  ftreet  by  the  light  of 
a  fire  made  of  heiwp  Italks.  All  the  volcanick  phenomena  then  difap- 
peared,  and  the  explanation  of  the  obfervatioiis  made  on  this  fubjecft  be- 
came very  limple.  In  the  fpring,  the  fire  was  weak,  becaufe  it  was  fed 
with  wood,  which  afforded  hQui  and  light ;  daring  the  fummer,  hemp 
Italks  v.'ert  burned,  becaufe  light  only  was  wanted.  At  that  time  there 
were  three  fires,  bccaufc  th-;  f^rir  of  Saint  Efprit  was  ccii':  at  hand,  at  which 


IH 


Volcanich.  Phenotmha^ 


When  the  decompofitlon  of  the  pyrites  is  advanced,  and  the 
vapours  and  elaftick  Raid  can  no  longer  be  contained  in  the  bow* 
els  of  the  earth,  the  ground  is  (haken,  and  exhibits  the  phenom- 
ena of  earthquakes.  Mephitick  vapours  are  multiplied  on  the 
furface  of  the  ground,  and  dreadful  hollow  noifes  are  heard.  In 
Iceland,  the  rivers  and  fprings  are  f  wallowed  up  ;  a  thick  fmoke 
mixed  with  fparks  and  lightning  is  then  difengaged  from  the 
crater  j  and  naturalifts  have  obferved  that,  when  the  fmoke  of 
Vefuvius  takes  the  form  of  a  pine,  the  eruption  is  near  at  hand. 

To  thefe  preludes,  which  (liow  the  internal  agitation  to  be 
great,  and  that  obftacles  oppofe  the  ilTue  of  the  volcanick  matters^ 
fi^cceedfr  an  eruption  of  ftones  and  other  products,  which  the  la- 
f j|  ilrives  before  it  :  and  laftly  appears  a  river  of  lava,  which 
flows  out,  and  fpreads  itfelf  down  the  fides  of  the  mountain^ 
At  this  period  the  calm  is  reftored  in  the  bowels  of  the  earth, 
and  the  eruption  continues  without  earthquakes.  The  violent 
efforts  of  the  included  matter  fometimes  caufe  the  fides  of  the 
mountain  to  open  ;  and  this  is  the  caufe  which  has  fuccefTively 
formed  the  fmaller  mountains  which  furround  volcanos.  Mon- 
tenuovo  which  is  a  hundred  and  eighty  feet  high,  and  three  thou- 
fand  in  breadth,  was  formed  in  a  night. 

This  cjrifis  is  fometimes  fucceeded  by  an  eruption  of  afhes 
which  darken  the  air.  Thefe  afhes  are  the  lafl:  refult  of  the  al- 
teration of  the  coals  ;  and  the  matter  which  is  firft  thrown  out 
is  that  which  the  heat  has  half  vitrified.  In  the  year  1767,  the 
allies  of  Vefuvius  were  carried  twenty  leagues  out  to  fea,  and  the 
llrects  of  Naples  were  covered  with  them.  The  report  of  Dion, 
concerning  the  eruption  of  Vefuvius  in  the  reign  of  Titus,  where- 
in the  afhes  were  carried  into  Africa,  Egypt,  and  Syria,  feems 
to  be  fabulous.  Mr.  de  SaufTure  pbferves  that  the  foil  of  Rome 
\s  of  this  charadler,  and  that  the  famous  catacombs  are  all  made 
in  the  volcanick  afhes.       ... 

It  muft  be  admitted,  however,  that  the  force  with  which  all 
thefe  products  are  thrown,  is  aflonifhing.  In  the  year  1769,  1 
flone  twelve  feet  high,  and  four  in  circumference,  was  thrown 
to  the  diflance  of  a  quarter  of  a  mile  from  the  crater  :  and  in  the 
year  i  771,  Sir  William  Hamilton  obferved  ftones  of  an  enor- 
mous fize,  which  employed  eleven  feconds  in  falling. 

The  eruption  of  volcanos  is  frequently  aqueous  ;  the  water. 
Which  is  confmed,  and  favours  the  decompofitlon  of  the  pyrites 

tht\  fold  their  filk,  and  which  confequently  put  them  under  the  necefli- 
ty  oTexpediting  their  work.  As  thefe  obfervers  announced  their  arrival 
wtthtwich  noife,  the  country  people  drove  them  back  by  a  (hower  of 
iJcMies,  whicl)  the  Don  Quixotes  of  natural  hiflory  niight  have  taken  for  » 
volcaoici  f  ruption. 


Volcanick  FroduBs,  5 1  j 

is  fometlmes  flrongly  thrown  out.  Sea  fait  is  found  among  the 
ejected  matter,  and  likewife  fal  ammoniack.  In  the  year  1630, 
a  torrent  of  boiling  water,  mixed  with  lava,  deftroyed  Portici 
and  Torre  del  Greco.  Hamilton  faw  boiling  water  ejedied. 
The  fprings  of  boiling  water  in  Iceland,  and  all  the  hot  fprings 
which  abound  at  the  furface  of  the  globe,  owe  their  heat  only  to 
the  decompofition  of  pyrites. 

Some  eruptions  are  of  a  muddy  fubftance  ;  and  thefe  form 
the  tufa,  and  the  puzzolano.  The  eruption  which  buried  Her- 
culaneum  is  of  this  kind.  Hamilton  found  an  antique  head, 
whofe  impreflion  was  well  enough  preferved  to  anfwer  the  pur- 
pofe  of  a  mould.  Herculaneum,  at  the  leaft  depth,  is  feventy 
feet  under  the  furface  of  the  ground,  and  often  at  one  hundred 
and  twenty. 

The  puzzolano  is  of  various  colours.  It  is  ufually  reddlfh  5 
fometimes  grey,  white,  or  green  ;  it  frequently  confifls  of  pum- 
ice (lone  in  powder ;  but  fometimes  it  is  formed  of  calcined 
clay.  One  hundred  parts  of  red  puzzolano  afforded  Bergmann, 
filex    55,  alumine  20,  lime  5,  iron  20. 

When  the  lava  is  once  thrown  out  of  the  crater,  it  rolls  in 
large  rivers  down  the  fide  of  the  mountain  to  a  certain  diftance, 
which  forms  the  currents  of  lava,  the  volcanick  caufeways,  &c. 
The  furface  of  the  lava  cools,  and  forms  a  folid  cruft,  under 
which  the  liquid  lava  flows.  After  the  eruption,  this  cruft 
fometimes  remains,  and  forms  hollow  galleries,  v/hich  MeiTrs. 
Hamilton  and  Ferber  have  vifited  :  it  is  in  thefe  hollow  places 
that  the  fal  ammoniack,  the  marine  fait,  and  other  fubftances 
fublimc.  A  lava  may  be  turned  out  of  its  courfe  by  oppofing 
banks  or  dikes  againft  it :  this  was  done  in  1669,  to  lave  Catan- 
ia ;  and  Sir  William  Hamilton  propofed  it  to  the  knig  of  Naples, 
to  preferve  Portici. 

The  currents  of  lava  fometimes  remain  feveral  years  in  cool, 
ing.  Sir  William  Hamilton  obferved,  in  I76«^,  that  the  lava 
which  flowed  in  1766  was  ftill  fmoking  in  fome  places. 

When  the  current  of  lava  is  received  by  water  its  cooling  is 
quicker ;  and  the  mafs  of  lava  ftirinks  fo  as  to  become  divided 
into  thofe  columns  which  are  called  bafaltes.  The  famous 
Giants  Cauleway  is  the  molt  ailonifhing  effect  of  this  kind  which 
we  are  acquainted  with.  It  exhibits  thirty  thoufand  columns 
in  front,  and  is  two  leagues  in  length  along  the  fea  coalt. 
Thefe  columns  are  between  fifteen  and  fixteen  inches  in  diame- 
ter,  and  from  twenty-five  to  thirty  feet  long. 

The  bafaltes  are  divided  into  columns  of  four,  five,  fix,  and 
feven  fides.  The  emperor  Vefpafian  made  an  .entire  Itatue, 
with  fixteen  children,  out  of  a  fingle  column  of  bafaltes,  whicK 
he  dedicated  to  the  Nile,  in  the  temple  of  Peace. 


5i6  Volcanich  PrcduBs, 

Bafaltcs  afforded  Bergmann,  per  quintal,  filex  56,  alumine  15, 
lime  4,  iron  25. 

Lava  is  rometimes  fwelled  up  and  porous.  The  lighteil  is 
called  pumice-ftone. 

The  fubftances  thrown  out  by  volcanos  are  not  altered  by  fire.' 
They  eje£l  native  fubftances,  fuch  as  quartz,  cryftaJs  of  ame- 
thyft,  agate,  gypfum,  amianthus,  feld-fpar,  mica,  fliells,  fchorl,. 
&c. 

The  fire  of  volcanos  is  feldom  ftrong  enough  to  vitrify  the 
matters  it  throws  out.  We  know  only  of  the  yellovvifii  capilla- 
ry and  flexible  glafs  thrown  out  by  the  volcanos  of  the  ifland  of 
of  Bourbon  on  the  fourteenth  of  May  1766,  (M.  Commerfon,) 
and  the  lapis  gallinaceus  eje6"ted  by  iiecla.  Mr.  Egolfrjoufon, 
who  is  employed  by  the  Obfervatory  at  Copenhagen,  has  fettled 
in  Iceland,  where  he  ufes  a  mivror  of  a  telefcope  which  he  has 
made  out  of  the  black  agate  of  Iceland. 

The  flow  operation  of  time  decompofes  lavas,  and  their  re- 
mains are  very  proper  for  vegetation.  The  fertile  ifland  of  Si- 
cily has  been  every  where  volcanized.  I  obferved  feveral  an- 
cient volcanos  at  prefent  cultivated  ;  and  the  line  which  fepa- 
rates  the  other  earths  from  the  volcanick  earih,  conftitutes  the 
limit  of  vegetation.  The  ground  over  the  ruins  of  Pompeia  is 
highly  cultivated.  Sir  William  Hamilton  confiders  fubterrane- 
an  fires  as  the  great  vehicle  ufed  by  nature  to  extradf  virgin  earth 
out  of  the  bowels  of  the  globe^  and  repair  the  exhaufted  furface. 

The  decompontion  of  lava  is  very  flow.  Strata  of  vegetable 
earth,  and  pure  lava,  are  occafionally  found  applied  one  over  the 
other  ;  which  denote  eruptions  made  at  diftances  of  time  very 
remote  from  each  other,  fince  it  requires  nearly  two  thoufand 
years  before  lava  receives  the  plough.  An  argument  has  been 
drawn  from  this  phenomenon  to  prove  the  antiquity  of  the 
globe  :  but  the  fllence  of  the  moft  ancient  authors  concerning  the 
volcanos  of  our  kingdom,  of  which  we  find  fuch  frequent  traces, 
proves  that  thefe  volcanos  have  been  extinguiihed  from  time 
immemorial  ;  a  circurrifi.ance  which  carries  their  exiflence  to  a 
very  diftant  period.  Befides  this,  feveral  thoufand  years  of  con- 
pe<li:ed  obfervations  have  not  aflbrded  any  remarkable  change  in 
Vefuvius  or  Etna  ;  neverthelefs,  thefe  enormous  mountains  are 
vA\  volcanized,  and  confequently  formed  of  (Irata  applied  one 
upon  the  other.  The  prodigy  becomes  much  more  ftriking, 
when  we  obferve  that  all  the  furrounding  country,  to  very  great 
diftances,  has  been  thrown  out  of  the  bowels  of  the  earth. 

The  height  of  Vefuvius  above  the  level  of  the  fea  is  three  thou- 
fand fix  hundred  and  fifty-nine  feet  ;  its  circumference  thirty - 
four  thoufand  four  hundred  and  forty-four.     The  heiglit  of  Et- 


Petrified  Vegetables*  ^ij 

na  is  ten  thoufand  and  thirty-fix  feet  •,    and   its   circumference 
one  liundred  and  eighty  thoufand. 

The  various  volcanick  products  are  applicable  to  feveral  ufes. 

1.  The  puzzolano  is  oi  admirable  ufe  for  building  in  the  wa-^ 
ter  :  when  mixed  with  lime,  it  fpeedily  fixes  itlelf,  and  water 
does  not  foften  it,  for  it  becomes  continually  harder  and  harder, 
I  have  proved  that  calcined  ochres  afford  the  fame  advantage 
for  this  purpofe  ;  they  are  made  into  bulls,  and  baked  rti  a  pot- 
ter's furnace  in  the  ufual  manner.  The  experiments  made  at 
Sette,  by  the  commiffary  of  the  province,  prove  that  they  may 
be  fubftituted  with  the  greateft  advantage,  inftead  of  the  puz- 
zolano of  Italy. 

2.  Lava  is  likewife  fufceptible  of  vitrification  ;  and  in  this 
Hate  it  may  be  blown  into  opaque  bottles  of  the  greatefl;  light- 
nefs,  as  I  have  done  at  Erepian  and  at  Alais.  The  very  hard  la- 
va, mixed  in  equal  parts  in  wood  alhes  and  foda,  produced  an 
excellent  green  glafs.  The  bottles  made  of  it  were  only  half 
the  weight  of  common  bottles,  and  much  ftronger ;  as  was 
proved  by  my  experiments,  and  thofe  which  Mr.  Jolly  de  Fleu- 
ry,  ordered  to  be  made  under  his  adminiftration. 

3.  Pumice  ftone  likewife  has  its  ufes  ;  it  is  more  efpecially 
ufed  to  poliih  mod  bodies  which  are  fomewhat  hard.  It  is  em- 
ployed in  the  mafs  or  in  powder,  according  to  the  intended  pur- 
pole.  Sometimes,  after  levigation,  it  is  mixed  with  water  to 
render  it  fofier. 

CHAPTER    III. 

Concerning  the  Decompofition  of  Vegetables  in  the  Bowels  of  the  Earth. 

HERBACEOUS  plants, buried  in  the  earth,  are  flowly  decom- 
pofed  ;  but  the  waters  which  filter  through  and  penetrate  them 
relax  their  texture.  The  fairs  are  extracted  ;  and  they  become 
converted  into  a  ftratum  of  blackifh  matrer,  in  which  the  vege- 
table texture  is  ftill  difcernible.  Thefe  flrata  are  fometimes 
perceived  in  digging  into  the  earth.  But  this  alteration  is  infi- 
nitely more  perceptible  in  wood  itfelf,  than  in  herbaceous  plants. 
The  ligneous  body  of  a  tree  buried  under  the  ground  becomes 
of  a  black  colour,  more  friable,  and  breaks  liiort ;  the  fradure  is 
ihining  ;  and  the  whole  mafs  appears,  in  this  flate,  to  form  an 
uniform  fubftance,  capable  of  the  finelt  poliih.  The  wood  thus 
changed  is  called  Jet.  In  the  environs  of  Montpellier,  near  St. 
John  de  Cucule,  feveral  cart  loads  of  trunks  of  trees  have  been  dug 
up  wliofe  form  was  peifed'tly  preff  rvetl,  but  which  were  convert- 
ed into  jet.  In  the  works  at  Nifmes  pieces  cf  wood  were  found 
entirely  converted  into  the  llalc  of  Jet.     In  the   neighbourhood 


5lS  Combujiion  of  Vepetohles, 

of  Vachery,  in  Gevaudan,  a  jet  is  found,  in  which  the  texture 
of  the  wahiut  tree  is  very  difcernible.  The  tf^xture  of  the  beech 
is  feen  in  the  jet  of  Bofrup  in  Scania.  In  Guelbre  a  foreft  of 
pines  has  been  difcovered  buried  beneath  the  fand  ;  and  at 
Beichlitz  two  Itrata  of  coal  are  wrought,  according  to  Mr.  Jars, 
the  one  bituminous,  and  the  other  of  foffil  wood.  I  preferve 
m  the  cabinet  of  mineralogy  of  Languedoc,  feveral  pieces  of 
irood  whofe  external  part  is  in  the  Itate  of  jet,  while  the  inter- 
nal part  llili  remains  in  the  ligneous  ftate  ;  fo  that  the  tranfition 
from  the  one  to  the  other  may  be  obferved. 

Jet  is  capable  of  receiving  the  moft  perfect  polifli.  It  is 
made  in  toys,  fuch  as  buttons,  fnufF  boxes,  neck  laces,  and  other 
ornaments.  It  is  wrought  in  Languedoc,  near  Saint  Colombe, 
at  the  diftance  of  three  leagues  from  Caftelnaudray.  It  is 
ground  down,  and  cut  into  facets,  by  mills. 

Jet  foftens  in  the  fire,  and  burns  with  the  emiflion  of  a  fetid 
odour.  It  affords  an  oil  which  is  more  or  lefs  black,  but  may 
be  rendered  colourlefs  by  repeated  diftillations  from  the  earik 
of  Murviel. 


CHAPTER    IV. 

Concerning  the  A£lion  of  Air  and  Heat  upon  Vegetables. 

WHEN  the  heat  is  applied  to  a  vegetable  expofed  to  the  air, 
certain  phenomena  are  produced,  which  depend  on  the  com- 
bination of  pure  air  with  the  inflammable  principles  of  the 
plant  •,  and  this  is  combuftion. 

In  order  to  produce  a  commencement,  a  heated  body  is  ap- 
plied to  the  dry  wood  which  is  intended  to  be  fet  on  fire.  By 
this  means  the  principles  are  volatilized  in  the  fame  order  as  wc 
haTe  pointed  out  in  the  preceding  article.  A  fmoke  is  produc- 
ed, which  is  a  mixture  of  water,  oil,  volatile  falts,  and  all  the 
gafeous  products  which  refulr  from  the  combination  of  vital  air 
with  the  feveral  principles  of  the  vegetable.  The  heat  then  in- 
creafes  by  the  combination  of  the  air  itfelf,  becaufe  it  paffes  to 
the  concrete  ftate  :  and  when  this  heat  is  carried  to  a  certain 
point,  the  vegetable  takes  fire,  and  the  combuflion  proceeds  un- 
til all  the  inflammable  principles  are  deftroyed. 

In  this  operation  there  is  an  abforption  of  vital  air,  and  a  pro- 
du^^ion  of  heat  and  light.  The  combuftion  will  be  ftrongcr  in 
proportion  as  the  inflammable  principle  is  more  abundant,  as 
the  aqueous  principle  is  lefs  abundant,  as  the  wood  i§  more  re- 
(inous>  and. as  the  air  is  purer  and  more  condtnfed, 


Vegetable  Fibre t,  ^\^ 

The  disengagement  of  heat  and  light  is  more  confidcrable,  ac* 
cordingly  as  the  combination  of  vital  air  is  flronger  in  a  givea 
time. 

The  refidues  of  combuftion  confift  of  fubflances  which  arc 
volatilized,  and  fixed  fubftances  ;  the  one  forms  the  foot,  the 
other  the  allies. 

The  foot  partly  arifes  from  fubftances  imperfectly  buriie*!^ 
decompofed  only  in  part,  which  have  efcaped  the  adion  of  vital 
air.  Hence  it  is  that  the  foot  may  be  burned  over  again :  and 
hence  likewife  it  is  that,  when  the  combuftion  is  very  rapid  aad 
effedlual,  there  is  no  perceptible  fmoke  ;  becaufe  all  the  infiam- 
mable  matter  is  then  deftroyed,  as  in  the  cylinder  lamps,  violcufc 
fires,  &c. 

The  analyds  of  foot  exhibits  an  oil  which  may  be  extra£lc<! 
by  diftillation  ;  a  refin  which  may  be  taken  up  by  alcohol,  and 
which  arifes  either  from  the  ImperfeCl  alteration  of  the  refin  of 
the  vegetable,  or  the  combination  of  vital  air  with  the  volatile 
oil.  It  likewife  affords  an  acid,  which  is  often  formed  by  the 
decompolition  of  mucus  ;  and  it  is  this  acid,  of  great  utility  ia 
the  arts,  for  which  the  Academy  of  Stockholm  has  defcribed  a 
furnace  proper  for  colle6iing  it.  Soot  likewife  affords  volatile 
falts,  fuch  as  the  carbonate  of  ammoniack,  and  others.  A  flight 
portion  of  fibrous  matter  is  likewife  volatilized  by  the  force  of 
the  fire,  and  we  find  it  again  in  the  foot. 

The  fixed  principle  remaining  after  combuftion,  forms  the 
afhes.  They  contain  falts,  earths,  and  metals,  of  which  we 
have  already  treated.  The  falts  are  fixed  alkalis,  fulphatcs,  ni- 
trates, muriates,  &c.  ;  the  metals  are  iron,  gold,  manganefe,  &c., 
and  the  earths  are  alumine,  lime,  filex,  and  niagnefia. 


CHAPTER    V. 

Concerning  the  A<ftion  of  Air  and  Water,  which  determine  a  Commence- 
ment of  Formentation  that  feparates  the  Vegetable  Juices  from  die  Lig- 
neous Print. 

WHEN  the  decompolition  of  vegetables  is  facilitated  by  the 
alternate  adtion  of  air  and  water,  their  organization  becomes 
deftroyed;  the  conne6lion  between  the  various  principles  h 
broken  ;  the  water  carries  away  the  juices  ;  and  leaves  the  fibrous 
(kc!leton  naked,  fufliciently  coherent,  and  fufhciently  abundant 
in  certain  vegetables,  to  be  extracted  in  this  way.  Hemp  i« 
prepared  in  this  manner.  The  abbe  Rozier  attributes  the  ad- 
vantage  of  watering  to  the  fermentation  of  tlie  mucilaginous 
part.     M.  Prozet  has  proved  that  hemp  contains  an  extractive 


520  Vegetable  Fibres, 

and  reQnous  part ;  and  that  the  watering  deftroys  the  former, 
and  thefecond  is  detached  almoft  mechanically.  It  has  been 
obferved  that  the  addition  of  a  fmall  quantity  of  alkali  favours 
this  operation.  , 

Running  water  is  preferable  to  (landing  w^r  ;  becaufe  {land- 
ing water  keeps  up  and  deveiopes  a  flronger  fermentation, 
which  attacks  the  ligneous  part.  It  has  been  obferved  that  flax 
prepared  in  running  water  is  whiter  and  ftronger  than  that  which 
is  prepared  in  (landing  water.  The  (tagnant  water  has  likewife 
the  inconvenience  of  emitting  an  unpleafant  fmell,  pernicious  to 
the  animal  economy.  The  addition  of  alkali  corre£ls  and  pre- 
vents this  effecl. 

In  the  dioccie  of  Lodeve  the  young  (hoots  of  the  Spani{h  genet 
are  prepared  by  a  very  (imple  procefs.  It  is  fown  on  the  high 
grounds,  where  it  is  left  for  three  years  ;  at  the  end  of  which 
time  the  fprigs  or  young  fhoots  are  cut,  and  formed  into  bun- 
dles, which  are  fold  from  twelve  to  fifteen  fous  each.  The  firft 
operation  confifts  in  crufhing  them  with  a  beetle.  The  follow- 
ing day  they  are  laid  in  a  running  ftream,  with  (tones  upon 
them,  to  prevent  their  being  wafhed  away.  In  the  evening 
they  are  taken  out,  and  laid  in  a  heap  on  the  banks  of  the  river, 
upon  draw  or  fern,  covering  them  with  the  fame,  and  loading 
the  heap  with  ftones  :  this  operation  they  call  mettre  a  convert. 
Every  evening  they  throw  water  on  the  heap.  At  the  end  of 
eight  days  they  open  the  mafs,  and  find  that  the  bark  is  eafily 
feparated  fijom  the  wood.  They  take  the  packets,  one  after  the 
other,  and  beat  and  rub  them  (Irongly  with  a  flat  ftone,  till  the 
epidermis  of  the  extremities  is  well  cleared  off,  and  the  whole 
Item  becomes  white.  It  is  then  hung  to  dry  ;  and  the  bark 
which  was  feparated  from  the  ligneous  fubftance,  is  carded  and 
fpun,  and  made  into  very  ufeful  cloth.  The  peafants  are  ac- 
quainted with  no  other  linen  for  cloths,  facks,  Ihirts,  &c.  Eve- 
ry one  prepares  his  own,  none  being  made  for  fale. 

The  genet,  genilta  juncea,  has  likewife  the  advantage  of  af- 
fording a  green  food  to  cattle  during  the  winter  ;  at  the  fame 
time  that  it  fupports  the  earth  by  its  roots,  and  prevents  its  be- 
ing carried  down  into  the  vallies.  The  bark  of  the  mulberry 
tree  may  be  treated  in  the  fame  manner.  Olive  de  Serres  has 
defcribed  a  good  procefs  for  this  purpofe.  :.;; 

It  is  the  fkeleton  formed  by  the  vegetable  fibre  only,  and  de- 
prived of  all  foreign  matter,  which  is  uied  to  make  cloth  ;  it  is 
the  mod  incorruptible  principle  of  vegetation,  and  when  this 
fibre,  being  converted  into  cloth,  can  no  longer  be  ufed  as  fuch, 
it  is  fubje£ted  to  extreme  diviiion,  to  convert  it  into  paper.  The 
operations  for   this  purpofe  are  the  following  : — The  rags  ar-j 


Vegetable  Fermentation,  521 

cleaned,  and  laid  in  water  to  rot  ;  after  which  they  are  torn  by 
hooked  peftles  moved  by  water  :  the  fecond  peftles  under  which 
they  arc  made  to  pafs,  are  not  armed  with  hooks  like  the  firft, 
but  merely  v/ith  round  nails  ;  the  third  are  of  wood  only.  By 
this  means  the  i?ags  are  converted  into  a  paltc,  which  is  attenu- 
ated (till  more  by  boiling.  This  pafte  is  received  in  wire 
moulds,  dried,  and  forms  blotting  paper.  Writing  paper  is  dip- 
ped in  fize,  and  fometimes  glazed. 

CHAPTER    VL 

Concerning  the  Adlion  cf  Air,  of  Heat,  and  of  Water,  upon  Vegeta- 
bles. 

"WHEN  the  various  juices  of  vegetables  are  difFufed  in  water> 
and  the  action  of  this  fluid  is  favoured  by  the  combined  adiion 
of  air  and  heat,  a  decompofition  of  thefe  juices  en Tues.  The 
oxigenous  gas  may  be  confidered  as  the  firft  agent  of  fermenta- 
tion :  it  is  afforded  either  by  the  atmofphere,  or  by  the  water 
which  is  decompofed. 

It  was  from  an  obfervatlon  of  thefe  facts  that  Becher  thought 
himfelf  authorized  to  confider  fermentation  as  a  kind  of  combuf- 
tion  : — «  Nam  combuftio,  feu  calcinatio  per  fortem  ignem,  hcet 
putrefadtionis  fpecics,  eidemque  analoga  fit — fermentatio  ergo 
definitur,  quod  lit  corporis  denfioris  rarefaftio,  particularumque 
aerearum  interpofitio,  ex  quo  concluditur  debere  in  acre  fieri, 
nee  nimium  frigido  nee  nimium  calido,  ne  partes  raribiles  expel* 
lantur,  in  aperto  tamen  vafe,  vel  tantum  vacuo  ut  partes  rare- 
fieri  queant ;  nam  ftri^ta  ciofura,  et  vafis  impletio,  fermentation- 
em  totaliter  impcdit" — Becher,  Phyf.  Subft.  f.  i.  15,  v.  cap.  1 1, 

P-3I3- 

The  conditions  necefTary  for  the  eftablifhment  of  fermenta- 
tion are — i.  The  contact  of  pure  air.  2.  A  certain  degree  o£ 
heat.  3.  A  quantity  of  water  more  or  lefs  confiderable,  which 
produces  a  difference  in  the  effedts. 

The  phenomena  which  ef!entially  accompany  fermentation 
are — i.  The  production  of  heat.  2.  The  abforption  of  oxi- 
genous gas. 

Fermentation  may  be  alTilled — I*.  By  increafing  the  mafs  of 
fermentable  matter.     2.  By  ufmg  a  proper  leaven. 

I.  By  increafing  the  fermentable  mafs,  the  princioles  oa 
which  the  air  mult  a6t  are  multiplied  ;  confequently  the  a(5tion 
of  this  element  is  facilitated  ;  more  heat  is  therefore  produced 
by  the  fixation  of  a  greater  quantity  of  air  %  and  confequently 
the  fermentation  Is  promoted  by  the  two  Caufes  which  inoft  em- 
inently maintain  it,  heat  and  air. 
3...T 


4 

r 


522  Conditiom  far  spirituous  Fermentation, 

2.  Two  kinds  of  leaven  may  be  diftinguKhed.  i.  godles 
eminently  putrefcible,  the  addition  of  which  hatlens  the  fermen- 
tation. 2.  Thofe  which  already  abound  with  oxigene,  and  which 
confequently  afford  a  greater  quantity  of  this  principle  of  fer- 
mentation. This  effccl  is  produced  by  the  inhabitants  of  the 
banks  of  the  Rhyne,  by  throwing  frelh  meat  into  the  vintage, 
to  haften  the  fpirituous  fermentation  (Linne  Amcenit^  Acad. 
DilTert.  de  GeneG  CalcuU)  :  and  fo  likewife  the  Chinefe  throw 
excrements  into  a  kind  of  beer,  made  of  a  decoclion  of  barley 
snd  oats.  And  on  this  account  it  is  thrit  the  acids,  the  neutral 
falts,  chalk,  rancid  oils,  and  the  metallick  calces,  &c.  haften  fer- 
mentation. 

The  produOs  of  fermentation  have  caufed  different  fpecies  to 
be  diilinguifhed  ;  but  this  variety  of  effects  depends  on  the  va- 
riety of  principles  in  the  vegetables.  When  the  faccharine  prin- 
ciple predominates,  the  refult  of  the  fermentation  is  a  fpirituous 
liquor  ;  when,  on  the  contrary,  the  mucilage  is  moft  abundant, 
the  product  is  acid  ;  if  the  gluten  be  one  of  the  principles  of 
the  vegetable,  there  will  be  a  production  of  ammoniack  in  the 
fermentation  :  fo  that  the  fame  fermentable  mafs  may  undergo 
different  alterations,  which  always  depend  on  the  nature  and  re- 
fpective  properties  of  the  conilituent  principles,  the  fufceptibili- 
ty  of  change,  &c.  Thus  a  faccharine  liquid,  after  having  un- 
dergone the  fpirituous  fermentation,  may  be  fubjeQed  to  the 
acid  fermentation  by  the  decompofition  of  the  mucilage  which 
had  refifted  the  fir  ft  fermentation  :  but  in  all  cafes  the  concourfe 
of  air,  water,  and  heat,  is  ncceffary  to  develope  fermentation. 
We  ihall  therefore  confine  ourfelves  to  the  examination  of  thefe 
three  agents — i.  On  the  juices  extracted  from  vegetables,  and 
diffufed  in  water,  which  conftitutes  the  fpirituous  and  acid  fer- 
mentations ;  2.  On  the  vegetable  itfelf,  which  will  lead  us  to 
the  formation  of  vegetable  mould,  ochres,  &c. 


ARTICLE    I. 

Concerning  the  Spirituous  Fermentation  and  its  Produifls. 

That  fermentation  is  diftinguiftied  by  the  name  of  Spirituous, 
which  affords  ardent  fpirit,  or  alcohol,  as  its  product  or  refult. 

It  may  be  conlldered  as  a  fundamental  principle,  that  no  fub- 
it^nces  are  capable  of  this  fermentation  but  faccharine  bodies. 
Pure  fugar  mixed  with  water  forms  taffia,  or  rum,  by  fermenta- 
tion ;  and  we  find  this  principle  in  the  analyfis  of  all  the  bodies 
which  are  fufceptible  of  it. 


spirituous  Fermentailm,  ja^ 

In  order  to  develope  this  fermentation,  therfe  is  r^quir^d,  i. 
The  accefs  of  air.  2.  A  degree  of  heat  between  ten  and  fifteen 
of  Reaumur.  3.  The  divifion  and  exprefuon  of  the  juice  con- 
tained in  the  fruits,  or  in  the  plant.  i|.  A  raafs  or  volume 
fomewhat  confiderable. 

We  will  make  the  application  of  thefe  principles  to  the  fer- 
mentation of  grapes.  When  thefe  are  ripe,  and  the  faccharinc 
principle  is  developed,  they  are  then  prelled,  and  the  juice  which 
ilows  out  is  received  in  veflels  of  a  proper  capacity,  in  which 
the  fermentation  appeafs,  and  proceeds  in  the  following  manner 
« — At  the  end  of  feveral  days,  and  frequently  after  a  few  hours, 
according  to  the  heat  of  the  atmofphere,  the  nature  of  the  grapes 
the  quantity  of  the  liquid,  and  the  temperature  of  the  place  in 
which  the  operation  is  performed,  a  movement  is  produced  in 
the  liquor,  which  continually  increafes  ;  the  volume  of  the  flu- 
id increafes  ;  it  becomes  turbid  and  oily  -,  carbonick  acid  is  dif- 
engaged,  which  fills  all  the  unocupied  part  of  the  veflel,  and 
the  temperature  rifes  to  the  i8th  degree.  At  the  end  of  feveral 
days  thefe  tumultuous  motions  fubfide,the  mafs  falls,  the  liquor 
becomes  clearer,  and  is  found  to  be  Icfs  i'accharine,  more  odor- 
ant,  and  of  a  red  colour,  from  the  reaction  of  the  ardent  fpirit 
upon  the  colouring  matter  of  the  pellicle  of  the  grape.* 

The  caufes  of  an  imperfe^l  fermentation  are  the  following  9 
I .  If  the  heat  be  too  little,  the  fermentation  languilhes,  the  fac- 
charine  and  oily  matters  are  not  fufficientiy  elaborated,  and  the 
wine  is  unduous  and  fweet. 

2.  If  the  faccharine  body  be  not  fufficientiy  abundant,  as 
happens  in  rainy  feafons,  the  wine  is  weak,  and  the  mucilage 
which  predominates  caufes  it  to  become  four  by  its  decompoli- 
tion. 

3.  If  the  juice  be  too  watery,  concentrated  and  bjiling  muft 
is  added. 

4.  If  the  faccharine  principle  be  not  fufficienlly  abundant, 
the  defect  may  be  remedied  by  the  addition  of  fugar.  Mac- 
quer  has  proved  that  excellent  wine  may  be  made  of  verjuice 
and  fugar  ;  and  Mr.  de  Bullion  has  ma^^e  wine  at  Bellejamcs 
with  the  verjuice  of  his  vine  rows  and  moid  fugar. 

There  have  been  many  difputes  to  determine  whether  grapes 
fliould  be  prelled  with  the  italks  or  without.     It  feems   to   me 

*  Richardfon,  in  his  Treatife  on  Brewing;,  infifls  much  on  the  differ- 
ence between  thefpecilick  gravity  of  the  Huid  bctore  and  after  fermenta- 
tion, wliich  he  conlidcrs  as  proportional  to  the  llreugth  or  inebriating 
quality  of  the  fluid.  Fermented  liquors  have  a  lefs  fpecifick  gravity  than 
they  pofl'elled  before  the  fermentation.  This  circumllunce  well  dcicives 
the  attention  of  the  raanulkdurer.    T. 


Jt24  Spirituous  Fermentation. 

that  this  depends  on  the  nature  of  the  fruit.  When  they  ara 
highly  charged  with  faccharine  and  mucilaginous  matter,  the 
ftalk  corredls  the  infipidity  of  the  wine  by  its  bitter  principle  : 
but  when,  on  the  contrary,  the  juice  is  not  too  fweet,  the  Italk 
renders  it  drier,  and  very  rough. 

The  wine  is  ufually  taken  out  of  the  fermenting  veflels  at  the 
the  period  when  all  the  phenomena  of  fermentation  have  fubfi- 
ded.  When  the  mafs  is  fettled,  the  colour  of  the  liquor  is  well 
developed,  when  it  has  become  clear,  and  its  heat  has  difap- 
pearcd  j  it  is  put  into  cafks,  where,  by*  a  fecond  infenfible  fer- 
mentation, the  wine  is  clarified,  its  principles  combine  -mor^ 
perfeftiy  together,  and  its  tafte  and  fmell  become  rnore  and 
more  developed. 

If  this  fermentation  be  (topped  or  fufFocated,  the  gafeoug 
principles  are  retained,  and  the  wine  is  brifKer,  and  more  of  the 
nature  of  muft.  Becher  had  very  proper  ideas  of  the  effedls  of 
thefe  two  fermentations. 

Diftinguiter  autem  inter  fermentationem  apertum  et  claufam^ ; 
i-n  aperta  potus  fermentatus  fanior  e(l,  fed  debiiior  j  in  claufa 
non  ita  fanus,  fed  forlior  :  caufa  eft  quod  evapcrantia  raref<i£l:a 
corpufcula  imprimis  Ji^dgna  adhuc  fiiveftrium  fpirituum  copia, 
de  quibus  antea  egimus,  retineatur  et  in  ipfum  potura  fe  pre-, 
cipitet,  unde  valde  eum  forieni  reddit.  Beclier,  Phyf.  Subt, 
lib.  i,v.  V.  cap.  1 1,  p.   313. 

It  appears,  from  the  intercfting  experiments  of  the  Marquis 
de  Bullion,  that  the  vinous  fermentation  does  not  take  place 
unlefs  tartar  be  prefent. 

By  evaporating  the  muft  of  grapes,  a  fait  is  obtained,  which 
has  the  appearance  of  tartar,  and  forms  fait  of  Seignette  with 
the  alkali  of  foda.  A  large  quantity  of  fugar  is  alfo  obtained. 
For  this  purpofe  the  tartar  is  firft  to  be  extracted  ,  after  which 
the  muft  having  evaporated  to  the  confiftence  of  a  thick  fyrup, 
is  to  be  left  for  fix  months  in  a  cellar.  At  the  expiration  of 
this  time,  the  fugar  is  found  in  a  confufed  Hate  of  cryftaliiza- 
tion  \  and  this  being  waihed  with  fpirit  of  wine,  to  carry  off 
the  colouring  part,  becomes  very  fine  and  pure. 

Wine  deprived  of  this  tartar  ferments  no  more,  and  the  fer- 
mentation is  in  proportion  to  the  abundance  of  the  tartar. 
Cream  of  tartar  produces  the  fame  efl'e6t. 

It  appears  that  thefe  falts  a6t  only  as  leavens,  to  facilitate  th^ 
decompofition  of  the  faccharine  principle. 

The  juice  of  grapes  is  not  the  only  vegetable  fluid  fufcepti- 
of  the  fpirituous  fermentation. 

Apples  contain  a  juice  which  eafily  ferments,  and  produces 
eider.      Wild  apples  are   ufually  employed  for  this  purpof?. 


spirituous  Ferment  alien,  ^2t 

Thefe  are  bruifed,  and  the  juice  prefTed  out,  which  ferments 
and  exhibits  the  fanie  phenomena  as  the  juice  of  grapes. 

In  order  to  have  cider  fine,  it  is  to  be  decanted  off  the  lees 
as  foon  as  the  tumultuous  fermentation  has  fubfided,  and  it  be- 
gins to  be  clear.  Sometimes,  in  order  to  render  it  milder,  a 
certain  quantity  of  the  juice  of  apples  recently  exprefled  is  ad- 
ded, which  produces  a  fecond  fermentation  in  the  cider  lefs 
ftrong  than  the  firft.  The  cider  which  is  left  to  ftand  on  the 
lees  acquires  ftrength  by  that  means.  Cider  affords  the  fame 
produdls  as  wine  ;  but  the  brandy  obtained  from  it  has  a  dif- 
agreeable  flavour,  becaufe  the  mucilage,  which  is  very  abundant 
in  the  cider,  is  altered  by  the  aclion  of  the  heat  of  diftillation. 
But  if  it  be  cautioufly  diftilled,  it  afrords  excellent  brandy,  ac- 
cording to  the  experiments  of  M.  Darcet. 

The  juice  of  the  harlheft  kind  of  pears  affords,  by  fermenta- 
tion, a  kind  of  cider  called  Perry. 

Cherries  likewife  afford  a  tolerably  good  wine  ;  and  a  kind 
of  brandy  is  obtained  from  them,  which  the  Germans  call  Kir- 
fchenwaffer. 

In  Canada  the  fermentation  of  the  faccharine  juice  of  the  ma- 
ple affords  a  very  good  liquor  ;  and  the  Altiericans,  by  fermen- 
ting the  impure  fyrups  of  fugar  with  two  parts  of  water,  form  a 
liquor  which  affords  the  fpirit  called  Tafiia,  or  Rum,  by  the 
Englifh. 

A  drink  called  Beer  is  likewife  prepared  with  certain  grain  ; 
fuch  as  wheat,  oats,  and  barley  ;  but  more  cfpecially  with  the 
latter,  i.  The  grain  is  made  to  fprout  or  vegetate,  by  fleeping 
it  in  water,  and  placing  it  in  a  heap.  By  this  means  the  gluti- 
nous principle  is  deftroyed.  2.  It  is  torrefied  or  lloved,  to  Hop 
the  progrefs  of  the  fermentation,  and  fit  it  tor  the  mill.  3  It 
is  fifted,  to  feparate  the  fprouts  or  radicles.  4.  It  is  ground 
into  a  very  coarfe  flour,  named  Malt.  5.  The  malt  is  infufed 
in  hot  water,  in  the;  maih  tub.  This  diffolves  the  fugar  and  the 
mucilage,  and  is  called  the  firft  wort.  It  is  then  drawn  off, 
heated,  and  again  poured  on  the  malt,  which  forms  the  fecond 
wort.*  6.  This  infufioii,  or  wort,  is  boiled  with  a  certain 
quantity  of  hops,  which  communicate  an  extractive  lefinous 
principle  to  it.  7.  An  acid  leaven,  or  fermenr,  is  added,  and  it 
is  poured  into  a  cooler,  where  it  undergoes  the  fpirituous  fer- 
Tiiemation.     When  tlic  term<^nration  has  fubfided,  it    is  ilirreci 


*  In  our  brev.'eries  this  praiftice  is  only  ufed  for  double  ales  :  and  the 
ffrengrhs  in  other  criles  nrerc-gulatcd  by  the  number  of  times  the  fame 
nialt  is  v/etted;  and  the  ume  oi  iatr.fio.i     The  third  mafliing  affords  fmall 


g26  Splriiuous  Ferment^tidn, 

and  put  into  calks,  where  it  contiftues  to  ferment,  tnd  thrCD^^s 
off  a  frothy  fcum  by  the  bung,  which  becomes  four,  and  ferves 
as  a  ferment  for  future  brewings  under  the  narrte  of  Yeaft. 

The  produft  of  all  the  fubftances  is  a  liquor  more  or  lefs  col- 
oured, cap^ible  of  affording  ardent  fpirits,  by  diftilJation,  of  an 
aromatick  and  refinous  fmeJI,  a  penetrating  hot  tafte,  which 
Simulates  the  a£lion  of  the  fibres. 

Wine  is  an  excellent  drink,  and  is  alfo  ufed  as  the  \'ehicle  of 
certain  medicines.  Such  are — i.  The  emetick  wine,  which  is 
prepared  by  digefling  two  pounds  of  good  white  wine  on  four 
ounces  of  the  crocus  metallorum.  2.  Chalybeated  wine,  made 
by  digefting  one  ounce  of  fteel  filings  in  two  pounds  of  white 
wine.  3.  The  wines  in  which  plants  are  infufed  ;  fuch  as 
wormwood,  forrel,  and  the  liquid  laudanum  of  Sydenham,  which 
is  made  by  digefling  for  feveral  days  two  ounces  of  fliced  opium, 
one  ounce  of  fafFron,  one  dram  of  pounded  cinnamon  and  of 
cloves,  in  one  pound  of  Spanifh  wine. 

We  fhall  proceed  to  examine  the  conflituent  principles  of 
thefe  fpirituous  liquors  by  taking  that  of  grapes  for  an  example. 
The  moment  the  wine  is  in  the  calk,  a  kind  of  analyfis  takes 
place,  which  is  announced  by  the  feparation  of  fome  of  its  con- 
flituent principles  5  fuch  as  the  tartar  which  is  depofitcd  at  the 
fides,  and  the  lees  which  are  precipitated  to  the  bottom  :  fo  that 
there  remain  only  the  ardent  fpirit  and  the  colouring  matter 
diffufed  in  a  volume  of  liquid^  which  is  more  or  lefs  confider- 
able. 

I.  The  colouring  principle  is  of  a  relinous  nature,  and  is  con-» 
taincd  in  the  pellicle  of  the  grape  j  and  the  fluid  is  not  coloured 
until  the  wine  is  formed  ;  for  until  then  there  is  nothing  which 
can  dlllblve  it ;  and  hence  it  is  that  white  wine  may  be  made  of 
red  grapes,  when  the  juice  of  the  grape  is  exprcfled,  and  the 
half  thrown  away.   ' 

If  wine  be  evaporated,  the  colouring  principle  remains  in  the 
refidue,  and  may  be  extrai^ed  by  fpirit  of  wine. 

Old  wines  lofe  their  colour,  a  pellicle  being  precipitated, 
which  is  either  depofited  on  the  fides  of  the  bottles,  or  falls  to 
the  bottom.  If  wine  be  expofed  to  the  heat  of  the  fun  during 
the  funuuer,  the  colouring  matter  is  detached  in  a  peUicle, 
which  falls  to  the  bottom  ;  when  the  veflei  is  opened,  the  dif- 
colouring  is  more  fpeedy,  and  it  is  effe<fled  .  in  two  or  three  days 
during  the  fummer.  The  wine  thus  deprived  of  its  colour  is 
not  perceptibly  weakened. 

1.  Wine  is  ufuaily  decompofed  by  dlflillation  ;  and  the  firfl 
product  of  the  operation  is  known  by  the  name  of  Brandy. 


Dyiillat'wn  of  Ardent  spirit,  ^ly 

Brandies  have  been  made  fince  the  thirteenth  century  ;  and 
it  was  in  Languedoc  where  this  commerce  firft  originated.  Ar- 
nauld  de  Villeneuve  appears  to  have  been  the  author  of  this 
difcovery.  The  alemblcks  in  which  wine  was  diftilled  confided 
for  a.  long  time  of  a  kind  of  boiler,  furmounted  with  a  long  cyl- 
indrick  neck,  very  narrow,  and  terminating  in  an  hollow  hemi- 
fphere,  in  which  the  vapours  were  condenfed.  To  this  fmall 
capital  was  adapted  a  narrow  tube,  to  convey  the  fluid  into  the 
ferpentine  or  worm  pipe.  This  diftillatory  apparatus  has  been 
fucceflively  improved.  The  column  has  been  confiderably  low- 
ered ;  and  the  (tills  generally  adopted  for  the  diftillation  of  wines 
in  Languedoc  are  nearly  of  the  following  form.  The  body  of 
the  flill  is  flat  at  bottom,  and  the  fides  rife  perpendicularly  to 
the  height  of  twenty  one  inches.  At  this  height  the  fides  in- 
cline inwards,  fo  as  to  diminifh  the  opening  to  twelve  inches. 
This  opening  ends  in  a  neck  of  feveral  inches  long,  which  re- 
ceives the  bafis  of  a  fmall  covering  called  the  head,  which  ap- 
proaches to  the  figure  of  an  inverted  cone.  From  the  angle  of 
the  upper  bafe  of  the  capital,  there  iffues  a  fmall  beak,  intended 
to  receive  the  vapours  of  brandy,  aad  tranfmit  them  into  the 
worm  pipe  to  which  it  is  adapted.  This  worm  pipe  has  five 
or  fix  turns,  and  is  placed  in  a  tub,  which  is  kept  filled  with  cold 
water,  to  condenfe  the  vapours. 

The  body  of  the  ftiil  is  ufually  furrounded  by  the  mafonry  as 
high  as  the  neck,  and  the  bottom  only  isexpofed  to  the  immedi- 
ate a£tion  of  the  fire.  An  afh-hole,  which  is  too  fmall,  a  fire- 
place large  enough,  and  a  chimney  place  oppofite  the  door  of 
the  fire-place,  conltitute  the  furnaces  in  which  thefe  ftills  are 
fixed. 

The  ftill  is  charged  with  between  five  and  fix  quintals  of  wine  : 
the  diftillation  is  made  in  eight  or  nine  hours  ;  and  from  fixty  to 
feventy.five  pounds  of  pit-coal  are  confumed  in  each  diftillation. 

Every  judicious  perfon  muft  be  aware  of  the  imperfection  of 
this  apparatus.     Its  principal  faults  are  the  following  : 

1 .  The  form  of  the  body  is  fuch  as  to  contain  a  column  of 
wine  of  confiderable  height  and  little  breadth,  which  being  a£l- 
ed  on  by  the  fire  at  its  bafe,  is  burned  at  that  part  before  the  up- 
per part  is  heated. 

2.  The  contraction  of  the  upper  part  renders  the  diftillation 
more  difficult  and  flow.  In  faCt,  this  inclined  part  being  con- 
tinually ftruck  by  the  air,  condenfes  the  vapours,  which  incef- 
fantly  return  into  the  boiler.  It  llkewife  oppofes  the  free  paf- 
fege  of  the  vapours,  and  forms  a  kind  of  eolopile,  as  Mr.  Baume 
has  obferved  ;  fo  that  the  vapours,  being  comprefled  at  this  nar- 
row neck,  Tea(5t  on  th-e  wine,  and  oppofe  its  further  afcent. 


528  DiJliUathn  of  Ardent  Spirit. 

3.  The  capital  is  not  conftruiEled  in  a  more  advaritagedti^ 
manner.  The  upper  part  becomes  of  the  fame  temperature  as 
the  vapours,  which  cannot  therefore  be  condenfed,  andj  by  theis 
rea£lion,  cither  fufpend  or  retard  the  diflillation.  # 

4.  In  addition  to  this  imperfedl  form  of  the  apparatus,  is" 
joined  the  mod  difadvantageous  method  of  adminiftering  the 
fire.  The  afh-hole  is  every  where  much  contracted  ;  the  fire- 
place is  very  large,  and  the  door  fliuts  badly.  In  confequence 
of  this,  a  current  of  air  pafles  between  the  combuftible  matter 
and  the  bottom  of  the  (till,  and  the  flame  is  driven  into  the 
chimney,  without  being  turned  to  advantage.  A  violent  fire  is 
therefore  required  to  heat  the  ftove  only  to  a  moderate  degree, 
in  this  defeft ive  conftrudlion. 

Several  other  degrees  of  perfecl:ion  have  been  fuccefllvely  ob- 
tained in  the  manufactories  of  Mr.  Joubert :  but  I  have  judged 
it  poflible  to  add  ftlll  more  to  what  was  known,  and  the  follow- 
ing are  the  principles  I  fet  out  from. 

The  whole  art  of  diftiliation  is  reduced  to  the  two  following 
principles: — i.  The  vapours  ought  to  be  difengaged,  and  raifed 
in  the  moft  economical  manner  ;  2.  And  their  cc^ndenfatioii 
ought  to  be  as  fpeedy  as  poflible. 

To  anfwer  the  firft  of  thefe  conditions,  it  is  necelTary  that  the 
boiler  fhould  prefent  the  largeft  polTible  furface  to  the  fire,  and 
that  the  heat  fhould  be  every  where  equally  applied.  2.  Thi 
fecond  condition  requires  that  the  afcent  of  the  vapours  fhould 
not  be  impeded,  and  that  they  fhould  ftrike  againil  cold  bodies, 
which  fhall  rapidly  condenfe  them. 

The  flills  which  I  have  conftruCled  upon  thefe  principles  arc 
more  broad  than  high  ;  the  bottom  is  concave,  in  order  that 
the  fire  maybe  nearly  at  an  equal  diftance  from  all  the  points  of 
its  furface  ;  the  fides  are  elevated  perpendicularly  in  fuch  a  man- 
ner that  the  body  exhibits  the  form  of  a  portion  of  a  cylinder  ; 
and  this  body  is  covered  with  a  vaft  capital,  furroundcd  by  its 
refrigeratory.  This  capital  has  a  groove  or  channel,  projecting 
two  inches  at  its  lower  part  within  :  the  fides  have  an  inclina- 
tion of  fixty-five  degrees  ;  becaufe  I  have  afcertained  that,  at 
this  degree,  a  drop  of  brandy  will  run  along  without  falling 
again  into  the  flill.  The  beak  of  the  capital  is  as  high  and  as 
wide  as  the  capital  itfelf,  and  infenfibly  diminifhes  till  it  comes 
to  the  worm-pipe  itfelf.  The  refrigeratory  accompanies  the 
beak,  or  neck,  and  has  a  cock  at  its  further  end,  which  fufFers 
the  water  to  run  out,  while  its  place  is  fuppHAl  by  other  cold 
water,   which  incelTantly  flows  in  from  above. 

When  the  water  of  the  refrigeratory  begins  to   be   warm,    a 
cock  is  then  opened,  that  it  may  efcape  in  proportion  as   it  is 


Diftillatlon  of  Ardent  Sj)lrit.  529 

frjore  plentifully  fupplied  from  above.  By  this  means  the  wa- 
ter is  kept  at  an  equal  temperature,  and  the  vapours  which  (Iriks 
againll  the  (ides  of  the  head  are  condenfed,  at  the  fame  time 
that  thofe  which  rife  fuffer  no  obftacle,  as  they  are  fubjecfted  to 
no  contraction  of  fpace.  In  this  conftrudion,  the  worm  pipe 
may  be  almoft  difpenfed  with,  becaufe  the  water  in  the  worm, 
tub  does  not  become  perceptibly  heated. 

Thefe  proceedings  are  very  economical  and  advantageous 
for  the  quality  of  the  brandy  is  better,  and  the  quantity  is 
larger. 

The  difliillation  of  the  wine  is  kept  up  until  the  prod u 61  is  no 
longer  inflammable.  'This  brandy  is  put  into  cafk^;,  when  it  be- 
comes coloured  by  the  extradlion  of  a  refmous  principle  contain- 
ed in  the  wood.  < 

The  wine  of  our  climates  affords  one  fifth  or  one  fourth  of 
brandy,  of  the  proof  ftrength  of  commerce. 

The  diitillation  of  brandy  by  a  more  moderate  heat  affords  a 
more  volatile  fluid,  called  Spirit  of  Wine,  or  Alcohol.  To  make 
common  fpirit  of  wine,  brandy  is  taken  and  diftilled  on  a  wa- 
ter bath  by  difliliation.*  This  fpirit  of  wine  may  be  purified 
and  reiflified  by  fubfequent  dillillations,  and  taking  only  the  firft 
portions  which  come  over. 

Alcohol  is  a  very  inflammable  and  very  volatile  fubflance.  It 
appears  to  be  formed  by  the  intimate  union  of  much  hydrogene 
and  carbone,  according  to  the  analyfis  of  Mr.  Lavoifier.  This 
fame  chemift  obtained  eighteen  ounces  of  water  by  burning  one 
pound  of  alcohol.  If  well  dephlegmated  alcohol  be  digefted 
upon  calcined  pot-afli,  and  afterwards  diilUled,  a  very  fweet  al- 
cohol is  obtained,  and  a  faponaceous  extract  which  affords  alco- 
Itol,  ammoniack,  and  an  empyreumatick  oil.  In  this  experiment 
the  formation  of  volatile  alkali  appears  to  arife  from  the  combi- 
nation of  the  hydrogene  of  the  alcohol  with  the  nirrogene  of  the 
pot-afli. 

There  are  various  methods  ufed  in  the  arts  to  judge  of  the 
degree  of  concentration  of  fpirit  of  wine.  Gunpowder  is  put 
into  a  fpcon,  and  moiflened  with  fpirit  of  wine,  which  is  fet  on 
fire  :  if  the  powder  takes  fire,  the    fpirit  is   confidered   to   be 


*  The  ardent  fpirit  fold  in  London  by  the  name  of  Spirit  of"  Wine,  or 
Lamp  Spirit,  is  made  by  the  rec'^iliers  of  malt  and  mclafles  fpiiit  in  Lon- 
don, by  dilliiration  of  the  rt- (idaes  of  their  compounded  fpirits.  It  is  pret- 
ty conibntly  ofthe  fpecitick  gravity  of  0,8*5  at  the  temperature  of  60 
Fahrenheit  5  and  may,  by  careful  rcdification,  be  brought  nearly  up  •  to 
o,8zc.  Dry  alki-^U  deprives  it  of  moie  of  its  water.  On  the  fubjedt  of 
the  Urcngth  of  fpirits,  tonfult  R'acden  io  Phil.  Triinf.  vol.  Ixxxi.  T. 
3...U 


53®  Formation  of  Ether, 

good  ;  but  the  contrary,  if  this  efFeft  does  not  take  place.  But 
this  merhod  is  fallacious,  becaufethe  efFe£l  depends  on  the  pro- 
portion in  which  the  fpirit  of  wine  is  ufed  ;  a  fmall  quantity  al- 
ways inflames  the  powder  y  and  a  ftrong  dofe  never  produces 
this  eirecl,  becaufe  the  water  which  remains  foaks  into  the  pow* 
der,  and  defends  it  from  the  combuftion. 

The  areometer  of  Mr.  Baume  is  not  to  be  depended  on  ;  be- 
caufe, in  the  ufe  of  it,  no  account  is  kept  of  the  temperature  of 
the  atmofphere,  which,  by  changing  the  denfity  of  the  fpirit  of 
wine,  is  produdive  of  a  change  in  the  refult  as  given  by  this  in- 
tlrument.  That  of  Mr.  Bories  is  more  accurate,  becaufe  the 
thermometer  is  adapted  to  it  ;  and  is  now  ufed  in  commerce. 

Alcohol  is  the  folvent  of  refins,  and  of  molt  aromatick  fub- 
(lances  ;  and  cortfequently  it  forms  the  balis  of  the  art  of  the 
varniOier  and  of  the  perfumer. 

Spirit  of  wine  combined  with  oxigene  forms  a  liquor  nearly 
infoluble  in  water,  which  is  called  ether. 

Ether  has  been  formed  with  molt  of  the  known  acids. 

The  rood  ancient  of  all  is  the  vitriolick  or  fulpliurick  ether. 
To  make  this,  a  certain  quantity  of  alcohol  is  put  into  a  retort, 
and  an  equal  weight  of  concentrated  fulphurick  acid  is  gradu- 
ally added.  The  mixture  is  fliaken  and  agitated,  to  prevent 
the  retort  from  breaking  by  the  partial  effect  of  the  heat  which 
arifes.  The  retort  is  then  placed  on  a  heated  fand  bath,  a  re- 
ceiver is  adapted,  and  the  mixture  is  heated  to  ebullition.  Alco- 
hol firft  pailes  over  ;  foon  after  which,  dreams  of  fluid  appear 
in  the  neck  of  the  retort,  and  within  the  receiver  which  denote 
the  rifing  of  the  ether.  Its  fmell  is  agreeable.  Vapours  of  ful- 
phureous  acid  fucceed  the  ether  ;  and  the  receiver  muft  be  ta- 
ken away  the  moment  they  appear.  If  the  dillillatlon  be  contin- 
ued, fulphureous  ether  is  obtained,  and  the  oil  which  is  called 
Etherial  Oil,  or  the  fweet  oil  of  wine  ;  and  that  which  remains 
in  the  retort  is  a  mixture  of  undecompofed  acid,  fulphur  and  a 
matter  refembling  bitumens. 

We  fee  that  in  this  operation  the  fulphurick  acid  is  decom- 
pofed  *,  and  that  the  oxigene  by  combining  with  the  hydrogene 
and  the  carbone  of  the  alcohol,  has  formed  three  flates,  which 
we  alfo  find  in  the  diftillation  of  fome  bitumens — i.  A  very  vol- 
atile oil  or  ether.     2.  Etherial  oil.     3.  Bitumen. 

If  the  fulphurick  acid  be  digefted  upon  ether,  it  converts  the 
whole  gradually  into  etherial  oil. 

When  the  ether  is  mixed  with  fulphtireous  vapours,  it  muft 
be  rectified  by  a  gentle  Ijgat  5  a  few  drops-  of  alkali  being  firft 
poured  in,  to  combine  with  the  acid. 


Format'ign  of  'Ether ^  5 3 1 

Sulphurick  ether  may  be  made  very  economipally,  by  jufing  a 
leaden  ftill  with  a  head  of  copper  well  tinned-  In  this  way  X 
prepare  it  by  the  quintal  without  any  difficulty. 

Mr.  Cadet  has  propofed  to  pour  on  the  refidue  of  the  retort 
one  third  p^rt  of  good  alcohol,  and  to  diilil  it  in  the  ufual 
way. 

Ether  is  very  hght,  very  volatile,  and  of  a  pleafant  fmell.  It 
is  fo  eafily  evaporated,  that  if  a  fine  rag  be  fteeped  in  this  liquor 
then  wrapped  round  the  ball  of  the  thermometer,  and  the  inftru- 
ment  be  agitated  in  the  air,  the  thermometer  fmks  to  the  freez- 
ing point.* 

Ether  eafily  burns,  and  exhibits  a  blue  flame.  It  is  very  fpar- 
ingly  foluble  in  water. 

Ether  is  an  excellent  antifpafmodick.  It  mitigates  pains  of 
the  colick  as  if  by  enchantment,  as  it  does  likewife  external 
pains.  The  celebrated  Bucquet  had  accuftomed  himfelf  fo 
much  to  this  drink,  that  he  took  two  pints  per  day  :  a  rare  ex- 
ample of  the  power  of  habit  on  the  conftitution. 

The  mixture  of  two  ounces  of  fpirit  of  wine,  two  ounces  of 
ether,  and  twelve  drops  of  etherial  oil,  forms  the  anodyne  li- 
quor of  Hoffman. 

Meifrs.  Navier,  Woulfe,  Laplanche,  Bouge,  and  others,  have 
defcribed  various  procefTes  for  making  nitrick  ether,  which 
are  more  or  lefs  eafily  imitated.  For  my  part,  I  take  equal  parts 
of  alcohol,  and  nitrick  acid  of  commerce,  of  the  ftrength  of  be- 
tween thirty  and  thirty-five  degrees.  I  put  the  whole  mto  a  tu- 
bulated retort,  which  I  fit  to  a  furnace,  and  adapt  two  receivers 
one  fucceeding  the  other.  The  firft  receiver  is  immerfed  in  a 
yefTel  of  water.  The  fecond  is  furrounded  by  a  wet  cloth  ;  and 
a  fiphon  communicates  from  its  tubal ure  to  a  vefTel  of  water  in 
which  it  is  plunged.  When  the  heat  has  penetrated  the  mix- 
ture much  vapours  are  difengaged,  which  are  condenfed  in 
ftriae,  on  the  ihteri^al  furfaces  of  the  receivers,  whofe  external 


*  Mr.  Carvallo  has  defcribed,  in  the  Philofophical  Tranf.  for  1781,  a 
pleafing  experiment  of  freezing  water  by  means  of  ether.  The  ether  is 
put  into  a  vial  fo  as  not  completely  to  hi]  it ;  and  in  the  neck  of  this  vial 
is  fitted  by  grinding,  a  tube  whofe  exteriour  end  is  drawn  out  to  a  capilla- 
ry iinenels.  Whenever  the  bottle  thus  flopped  is  inverted,  the  ether  is 
urged  out  of  the  tube  into  a  fineilream,  in  confequence  of  the  prefTure  ex- 
erted by  the  elaftick  etherial  vapour  which  opcupies  the  fuperiour  fpace  of 
the  bottle.  This  ftream  is  direa:ed  on  the  outlide  of  a  fmall  glafs  tube 
containing  water,  which  it  fpeediiy  cools  down  to  the  freezing  point ;  at 
which  inftant  the  water  becomes  fuddenly  opaque,  in  confequence  of  the 
icy  cryftallization.  Jf  a  bended  wire  be  previouily  immerftd  in  the  v/ater, 
it  ni^y  afterwards  be  drawn  Qut,  and  the  ice  along  with  it.    1'. 


53^  P^ormatton  of  Ether, 

furface  is  kept  cdnflantly  cold.  The  ether  whieh  I  obtain  is  ve- 
ry pure  and  very  abundant.* 

When  the  precaution  of  dlftilling  it  properly  is  attended  to, 
this  ether  becomes  nearly  fimilar  to  the  vitriolick.  Meflrs.  de 
Laflbne  and   Cornette   have  obferved  that  it  was  more  fedative. 

The  di{liilation>of  the  muriatick  acid  with  alcohol  produces 
only  a  mixture  of  thefe  two  Uquors,  which  is  called  the  Dulcifi- 
ed Muriatick  Acid. 

Before  the  theory  of  ethers,  and  the  fimple  procefs  of  com- 
bining a  furplus  of  oxigene  with  the  muriatick  acid,  were  known, 
methods  were  invented  to  procure  the  muriatick  ether,  but  fub- 
ftances  were  always  made  ufe  of  in  which  the  muriatick  acid 
was  oxlgenated.  In  this  manner  it  was  that  the  baron  de 
Bornes  propofed  the  concentrated  murinte  of  zinc,  mixed  and 
diftilled  with  alcohol ;  and  that  the  Marquis  de  Courtanvdux 
diftilled  the  mixture  of  a  pint  of  alcohol  with  two  pounds  and  a 
half  of   the  fuming  muriate  of  tin. 

The  theory  of  the  formation  of  ether  has  in  our  time  led  tq 
fimpler  procefies. 

Mr.  Pelletier  introduces  a  mixture  of  eight  ounces  of  man- 
ganefe,  and  a  pound  and  a  half  of  muriate  of  foda,  in  \  large 
tubulated  retort ;  twelve  ounces  of  fulphurick  acid,  ana  eight 
ounces  of  alcohol,  are  afterwards  added.  Diftillation  is  then 
proceeded  on  ;  and  ten  ounces  of  a  very  etherial  liquor  are  ob- 
tained, from  which  four  ounces  of  good  ether  are  afforded  by 
diftillation  and  reffcification. 

The  very  concentrated  muriatick  acid,  diftilled  from  manga- 
nefe  in  the  apparatus  of  Woulfc,  aff'ords  more  ether.  It  is  even 
fufficient,  for  this  purpofe,  to  pafs  the  oxigenated  muriatick  acid 
through  good  alcohol  to  convert  it  into  ether. 

This  muriatick  ether  has  the  greatefl  analogy  with  the  ful- 
phurick. It  differs  from  it  in  two  characters  only — i.  It  emits, 
an  burning,  a  fmeil  as  penetrating  as  that  of  the  fulphurick  acid. 
2.   Its  tafte  is  fcyptick,  refembling  that  of  alum. 

From  thefe  experiments  it  is  evident  that  ether  is  merely  a 
combination  of  alcohol  with  the  oxigene  of  the  acids  made  ufe 

*  The  ingenious  author  has  fprgotten  to  caution  the  inexperienced  chem- 
ift  againft  the  danger  of  K.ixing  thefe  two  liquors.  The  nitrous  acid  must 
be  very  gradually  added  to  thefpiritof  wine,  by  fmali  portions  at  a  time. 
It  isfaid,  and  uith  rc^ifon,  to  beef  great  import,)  nee,  that  tb.e  nitrous  acid 
be  added  to  the  fpirlt,  and  not  tl:C  fpirit  to  the  acid  ;  for,  in  this  laft  cale, 
the  mixture  will,  during  the  gicateft  part  of  the  time  of  the  operation  of 
combining  the  fluids  conwrc  of  a  large  portion  of  acid,  with  a  fmalier  por- 
tion of  fpirit ;  whereas,  where  the  contrary  method  is  adopted,  the  pro- 
portion of  fpirit  wit]  always  be  greater  than  that  of  the  acid,  until  the  \dX 
41-uantiiy  of  acid  is  added.    T. 


Purification  of  Tartar.  "j;^*^ 

of.     I  have  even  obtained  an  etherial  liquor  by  repeated  diftil- 
lations  of  good  alcohol  from  the  red  oxide  of  mercury. 

The  idea  of  Macquer,  who  confidered  ether  as  fpirit  of  wine 
dephlegmated,  or  depr-ved  of  water,  had  little  foundation  ;  for 
the  diftillation  of  the  fpirit  of  wine  from  the  moil  concentrat- 
ed or  dried  alkali,  never  affords  any  thing  but  fpirit  of  wine 
more  or  Icfs  dephlegmated. 

Concerning  Tartar. 

Tartar  is  depofited  on  the  fides  of  calks  during  fermentation  : 
ic  forms  a  lining  more  or  lefs  thick,  which  is  fcraped  off.  Thi^ 
is  called  crude  tartar,  and  is  fold  in  Languedoc  from  ten  to  fif- 
teen livres  the  quintal. 

All  wines  do  not  afford  the  fame  quantity  of  tartar.  New- 
man remarked  that  the  Hungarian  wmes  left  only  a  thin  (Ira- 
tum  ;  that  the  wines  of  France  afforded  more  ;  and  the  Rhen- 
idi  wines  afforded  the  pureft  and  the  greatefl  quantity. 

Tartar  is  diftinguiflied,  from  its  colour,  into  red  or  v/hite  : 
the  firit  is  afforded  by  red  wine. 

The  purefl  tartar  exhibits  an  imperfecflly  cryftallized  appear- 
ance ;  the  form  is  the  farne  we  have  affigncd  to  the  acidulous 
tartrite  of  pot-a(h  5  and  it  is  this  quality  which  is  called  grained 
tartar  (tartre  grenu)  in  our  refineries  at  MontpclJier. 

The  taile  of  tartar  is  acid  and  vinous.  One  ounce  of  water, 
at  the  temperature  of  ten  degrees  above  o  of  Reaumur,  diffolves 
no  more  than  10  grains  :  boiling  water  diffolves  more,  but  it  fallsi 
down  in  cryftals  by  cooling. 

Tartar  is  purified  from  an  abundant  extractive  principle  by 
proceffes  which  are  executed  at  Montpellier  and  at  Venice. 

The  following  is  the  proccfs  ufed  at  Montpellier  : — The  tar- 
tar Is  diffolved  in  water,  and  fuffered  to  cry!lalli?;e  by  cooling. 
The  cryftals  are  then  boiled  in  another  veflcl,  with  the  addition 
of  five  or  fix  pounds  of  the  white  argillaceous  earth  of  Murveil 
to  each  quintal  of  the  fait.  After  this  boiling  with  the  earth,  a 
very  white  fait  is  obtained  by  evaporation,  which  is  known  by 
the  name  of  Cream  of  Tartar,    or  acidulous  tartrite  of  pot-affo 

M.  Defmaretz  has  informed  us  (Journal  de  Phyf,  1771)  that 
the  procefs  ufed  at  Venice  confifts — i.  In  drying  the  tartar  in 
iron  boilers.  2.  Pounding  it,  and  diffolving  it  in  hot  water, 
which  by  cooling  affords  purer  cryflals.  3.  Redlffolving  thefe 
cryftalsin  water,  -and  clarifying  the  folution  by  white  of  eggs 
and  afhes. 

The  procefs  of  Montpellier  is  preferable  to  that  of  Venice* 
The  atidition  of  the  aihes  introduces  a  foreign  fait,  whlcl)  alters 
the  purity  of  the  produ(^.  * 


534  ^t:/^  of  Tartar  obtained. 

The  acidulous  tartrite  of  potafli  cryftallizes  in  tetrahedral 
prifms  cut  off  flantwife. 

This  fait  is  ufed  by  the  dyers  as  a  mordant :  but  its  greateft 
confumption  is  in  the  north,  where  it  is  ufed  at  table  as  a  fea- 
foner. 

Tartar  appears  to  exift  in  the  muft,  and  confequently  in  the 
grape  itfelf.  This  has  been  afcertained  by  the  experiments  of 
De  Rouelle  and  the  mavquis  de  Bullion. 

This  fait  exifts  in  many  other  vegetables-  It  is  fufficiently 
proved  that  tamarifck  and  fumach  contain  it ;  and  the  fame  is 
true  of  the  barberry,  of  balm,  carduus  benedi£lus,  reft-harrow, 
water-germander,  and  fage. 

The  acidulous  tartrite  of  pot-afh  may  be  decompofed  by 
means  of  fire,  in  the  way  of  diftillation  ;  in  which  cafe  the  acid 
and  the  alkali  are  obtained  feparately.  This  decompofition  may 
alfo  be  affeded  by  the  fulphurick  acid. 

The  celebrated  Scheele  has  defcribed  a  procefs  of  greater  ac- 
curacy for  obtaining  the  acid  of  cream  of  tartar. 

Two  pounds  of  the  cryftals  are  difTolved  in  water,  into  which 
chalk  is  thrown  by  degrees,  till  the  liquid  is  faturated.  A  pre- 
cipitate is  fornied,  which  is  a  true  tartrite  of  lime,  is  taftelefs, 
and  cracks  between  the  teeth.  This  tartrite  is  put  into  a  cucur- 
bit ;  and  nine  ounces  of  fulphurick  acid,  with  five  ounces  of 
water,  are  poured  on  it.  After  twelve  hours  digeftion  with  oc« 
cafional  ftirring,  the  tartareous  acid  is  fet  at  liberty  in  the  folu- 
tion,  and  may  be  cleared  of  the  fulphate  of  lime  by  means  of 
cold  water. 

This  tartareous  acid  affords  cryftals  by  evaporation  ;  which 
when  expofed  to  the  fire,  become  black,  and  leave  a  fpongy  coal 
behind. 

Treated  in  a  retort,  they  afford  an  acid  phlegm,  and  fome  oil. 

The  tafte  of  this  acid  is  very  (harp. 

It  combines  with  alkalis,  with  lime,  with  barytes,  aluminCj^ 
magnefia,  ^c. 

The  combination  of  pot  a{h  with  this  acid  forms  cream  of 
tartar,  when  the  acid  is  in  excefs ;  which  is  capable  of  entering 
iilto  combinations,  and  forming  triple  falts.  Such  is  the  fait  of 
Seignette,  or  tartrite  of  (oda,  which  cryftalize§  in  tetrahedral 
ihomboidal  prifms. 

The  acidulous  tartrite  of  potafti  is  very  fparingly  foluble  in 
water.  Boiling  water  diffolves  only  one  twenty-eighth  part. 
The  addition  of  borax  has  been  propofed  to  facilitate  the  folu-> 
tion  ;  as  likewife  fugar,  which  is  lefs  efficacious  than  borax, 
but  makes  a  very  agreeable  and  purgative  lemonade  with  this 


farmai'ion  of  Vinegaf^  535 

ARTICLE  IL 

Concerning  the  Acid  Fermentation. 

The  mucilaginous  principle  is  more  efpecially  the  fubftanc^ 
on  which  the  acid  fermentation  depends  ;  and  when  it  has  been 
deftroyed,  in  old  and  generous  wines,  they  are  no  longer  capable 
of  alteration,  without  the  addition  of  a  gummy  matter,  as  1  find 
from  my  own  experiments.  It  is  not  true,  therefore  to  fay 
that  all  fubftances  which  have  pafied  through  the  vinous  fer- 
mentation, are  capable  of  pafiing  to  the  ftate  of  vinegar  ;  fincc 
this  change  depends  on  the  mucilage,  which  may  not  in  all  cafetf 
be  prefent. 

There  are,  therefore,  three  caufes  neceffary  to  produce  the 
acid  fermentation  in  fpirituous  liquors. 

I.  The  exiftence  of  mucilaginous  matter,  or  mucilage.  2.  A 
degree  of  heat  between  eighteen  and  twenty-five  degrees  of 
Reaumur.     3.  The  prefence  of  oxigenous  gas. 

The  procefs  indicated  by  Boerhaave  for  making  vinegar,  is 
dill  the  moft  frequently  ufed.  It  confifts  in  fixing  two  cafks 
in  a  warm  room  or  place.  Two  falfe  bottorhs  of  balket  work 
are  fixed  at  a  certain  diftance  from  the  bottom,  upon  which  the 
tefufe  of  grapes  and  vine  twigs  are  placed.  One  of  thefe  tuns 
is  filled  with  wine,  and  the  other  only  half  filled.  The  fermen- 
tation begins  in  this  laft  ;  and,  when  it  is  in  full  action,  it  is 
checked  by  filling  the  cafk  up  v/ith  wine  out  of  the  other.  The 
fermentation  then  takes  place  in  the  laft  mentioned  cafk,  that 
remained  half  filled  ;  and  this  is  checked  in  the  fame  manner 
by  pouring  back  the  fame  quantity  of  liquid  out  of  the  other  ; 
and  in  this  way  the  procefs  is  continued  till  the  vinegar  is  made, 
which  is  ufually  in  about  fifteen  days. 

When  the  fermeintation  developes  itfelf,  the  liquid  becomes 
(leated  and  turbid  j  a  great  number  of  filaments  are  feen  in  it; 
it  emits  a  lively  fmell  ;  and  much  alir  is  abforbed,  according  to 
the  obfcrvation  of  the  abbe  Rozier. 

A  large  quantity  of  lees  is  formed,  which  fubfides  when  the 
vinegar  becomes  clear.  This  lees  is  very-  analogous  to  the  fi- 
brous matter. 

Vinegar  is  purified  by  diftillation.  The  firft  portions  which 
pafs  over  are  weak  ;  but  foon  afterwards  the  acetous  acid  arifes, 
and  is  (Ironger  the  later  it  comes  over  in  the  diftillation.  The 
fluid  is  called  Diftilled  Vinegar  ;  and  is  thus  cleared  of  its  coU 
curing  principle^  and  the  lef5p  which  is  always  more  or  Icf* 
abundant. 


53^  Radical  Vinegar,  or  Acetich  Acid, 

Vinegar  may  llkewife  be  concentrated  by  expofing  it  to  tlii; 
froft.  The  fuperabundant  water  freezes,  and  leaves  the  acid 
more  condenfed. 

The  prefence  of  fpirit  of  wine,  mucilage,  and  air,  are  necef- 
fary  to  form  vinegar.  Scheele  has  made  it  by  decompofing  the 
nitrick  acid  upon  fugar  and  mucilage.  I  communicated  to  the 
academy  at  Paris  (vol.  1786)  an  obfervation  of  fome  curiofity 
refpedling  the  formation  of  vinegar.  Diftilled  water,  impreg- 
nated with  vinous  gas,  affords  vinegar  :  at  the  end  of  fome 
months,  a  deppfition  is  made  of  a  fubftance  in  flocks,  which  is 
analogous  to  the  fibrous  matters  of  vegetables.  AVhen  the  wa- 
ter contains  fulphate  of  lime,  an  execrable  hepatick  odour  is  dci 
veloped,  a  depofition  of  fulphur  is  afforded,  and  all  this  is  ow- 
ing only  to  the  decompofition  of  this  fulphurick  acid.. 

As  in  the  above  experiments  I  had  placed  the  water  abov'e 
the  vinous  fluid  in  fermentation,  to  impregnate  it  in  the  carbon- 
ick  acid,  the  alcohol  which  evaporates  with  the  acid  carried 
the  mucilage  with  it  ;  and  the  effeds,  I  obferved,  are  referable 
to  this  fubftance. 

The  acetous  acid  Is  capable  of  combining  with  a  ftronger 
dofe  of  oxigene  ;  and  then  forms  radical  vinegar,  or  the  acetick 
acid. 

To  form  the  acetick  acid,  the  metallick  oxides  are  diffolved 
in  the  acetous  acid  ;  the  fait  which  is  obtained  being  then  ex- 
pofed  to  diftillation,  affords  the  oxigenated  acid.  It  has  a  Very 
lively  fmeil,  is  cauftick,  and  its  action  upon  bodies  is  very  dif- 
ferent from  that  of  the  acetous  acid. 

This  acetick  acid  has  the  advantage  of  forming  ether  with  al- 
cohol. For  this  purpofe,  equal  parts  of  the  acid  and  alcohol 
are  to  be  diftilled  together.  The  product  of  the  diftillation  is 
to  be  again  added  to  the  refidue  in  the  retort  ;  and  a  fmall 
quantity  of  tlie  water  of  Rabel  is  like  wife  to  be  added.  The 
whole  becomes  converted  into  ether. 

The  combination  of  the  acetous  acid  with  pot-afti  forms  the 
acetite  of  pot-afli. 

To  make  this  fait,  pure  pot-afti  is  faturated  with  diftilled  vin- 
egar, the  liquor  filtered,  and  evaporated  to  drynefs  in  a  glafs 
veffel  over  a  very  gentle  fire.  The  acetite  of  pot-afh  has  a  pen- 
etrating acid  tafte  5  is  decompofed  by  diftillation  ;  and  affords 
an  acid  phlegm,  an  empyreumatickoil,  amm.oniack,  and  a  large 
quantity  of  very  odorant  gas,  formed  of  carbonick  acid  and  hy- 
clrogene.  The  coal  contains  much  fixed  alkali  in  a  difengaged 
ftate.  This  fait  is  very  foluble  in  water,  and  deliquefces  in  the 
air. 


Putt'efa^ion  of  Vegetables,  537 

The  falphurick  acid  poured  upon  it,  decompofes  it  j  and  the 
torodudls  which  come  over  are  fulphurick  acid  and  acetick  acid. 

The  acetous  .acid  like  wife  combines  with  foda  ;  and  this 
combination  is  improperly  called  Cryftallizable  Terra  FoHata. 
The  acetite  of  foda  cryftallizes  in  ftriated  prifms,  and  does  not 
attract  the  humidity  of  the  air.  When  thefe  falts  arc  diftilled, 
they  leave  a  refidue,  which  forms  an  excellent  and  very  aflive 
pyrophorous. 

The  acetous  acid  likewife  combines  with  ammoniack.  The 
acetite  which  is  produced  is  called  the  fpirit  of  Mindereus.  This 
fait  cannot  be  evaporated  without  the  lofs  of  a  confiderable  part 
on  account  of  its  volatility  :  but,  by  a  long  evaporation,  it  af- 
fords needle  formed  cryftals,  of  a  hot  and  penetrating  tafte,  and 
attradling  moifture  from  the  air.  Lime,  fixed  alkalis,  mere 
heat  or  fire,  and  the  acids,  decompofe  this  fait. 

The  fulphate  of  p6t-a(h,  fprinkled  with  the  acetick  acid,  forms 
the  fait  of  vinegar. 

ARTICLE    IIL 

Concerning  the  Putrid  Fermentation. 

In  order  that  vegetables  may  undergo  the  two  fermentations 
we  have  treated  of,  it  is  neceflary  that  the  juices  fliould  be  ex- 
tra£led,  and  prefented  in  a  Confiderable  volume.  A  due  degree 
of  heat,  together  with  other  circumftances  artificially  brought 
together,  are  likewife  neceflary  ;  for  a  grape,  left  on  the  ftalk, 
produces  neither  ardent  fpirit  nor  vinegar,  but  rots.  It  is  this 
new  kind  of  alteration  we  (hall  at  prefent  proceed  to  treat  of. 

This  fermentation  is  the  mod  natural  termination  of  the  veg- 
etable. It  is  indeed  the  only  end  to  which  the  natural  courfe  of 
things  is  directed. -,  fince  it  is  by  this  means  that  the  exhaufted 
furface  of  the  globe  is  repaired.  The  two  other  fermentations 
are  the  mere  effects  of  art,  and  form  no  part  of  the  great  plan 
of  nature 

The  life  of  the  greateft  part  of  vegetables  lafts  but  a  few 
months  ;  but  the  feeds  they  depofite  aflure  their  re-prod uftion. 

There  are  other  more  robufl  vegetables  which  fupport  the  cold 
of  winter,  and  only  caft  their  leaves  at  that  period.  The  annual 
vegetables,  and  vivacious  plants,  are  altered  by  the  combined  ac- 
tion of  the  caufes  we  have  mentioned  :  and  the  refult,  accord- 
ing to  the  degree  of  decompofition,  is  either  manure,  vegetable 
earth,  or  ochre. 

The  conditions  of  the  vegetable  fermentation  are  the  follow- 
ing. 

3..W 


53^  Puirefacjion  of  Vegetables, 

1.  It  is  neceirary  that  the  organization  be  impregnated  with 
water.  Dried  vegetables  are  preferved  without  putrifying  ;  and 
if  they  be  moiilened,  their  fubfeqiient  alteration  is  prodigioufly 
accelerated.  In  this  manner  it  is  that  plants  heaped  together 
become  heated,  blacken,  and  take  fire,  if  not  fufficiently  dried. 
Fires  of  this  kind  are  not  rare,  and  the  theory  is  not  difficult  to 
be  explained.  Wetted  ropes,  moid  hay  heaped  together,  arrd 
in  a  word  every  vegetable  fubltance,  putrefies  or  rots  with  great- 
er facility,  the  more  perfectly  its  texture  is  impregnated  with 
water. 

2.  The  contaft  of  air  is  the  fecond  necefTary  caufe  in  the  pu- 
trefad-lion  of  vegetables.  It  is  reported,  in  the  Ephemerides  of 
the  Curious  in  Natural  Phenomena,  for  1787,,  that  ripe  cherries 
were  preferved  for  forty  years,  by  inclofing  them  in  a  veflel  well 
luted,  and  placed  at  the  bottom  of  a  well. 

3.  A  certain  degree  of  heat  is  likewife  necefTary.  The  heat 
between  five  and  ten  degrees  is  fufficient  to  caufe  decompofi- 
tion.  A  greater  heat  diffipates  the  humidity,  dries  the  vegeta- 
ble, and  preferves  it  from  putrefaction.  Too  little  heat  retards 
or  fufpends  it. 

4.  It  is  likewife  necefTary  for  the  due  efTe6l  of  this  decompofi- 
tion,that  the  vegetables  Ihould  be  heaped  together,  and  their  juices 
abundant.  A  greater  quantity  of  air  is  then  combined  with  the 
vegetable  -,  becaufe  the  juices  and  the  furfaces  are  then  more  con- 
(iderable  ;  and  confequently  a  greater  degree  of  heat  is  produ- 
ced, which  accelerates  the  decompofition. 

'V*^;ien  vegetables  are  heaped  together,  and  their  texture  is 
foftcned  by  the  humidity  with  which  they  are  impregnated,  to- 
gether with  their  own  juices,  the  phenomena  of  decompofition 
are  the  following  ;  the  colour  of  the  vegetable  is  changed  ;  the 
^reen  leavey  become  yellow,  the  texture  becomes  lax,  and  the 
parts  lefs  coherent  ;  \ht  colour  of  the  vegetable  itfelf  changes 
to  black  or  brown  ;  the  mafs  rifes,  and  perceptibly  fwells  up  ; 
the  heat  becomes  more  intenfe,  and  is  perceived  on  approach- 
ing the  lieap  ;  and  the  fumes  which  arife  have  already  a  fmell, 
which  fometimes  is  not  difagreeable  ;  at  the  fame  time  bubbles 
arife,  and  break  at  the  furface  of  the  liquid,  when  the  vegetables 
are  reduced  to  a  magma.  This  gas  is  a  mixture  of  nitrogene 
hydrogene,  and  carbonick  acid.  At  this  epocha,  likewife  an 
ammoniacal  gas  is  emitted,  which  is  formed  in  thefe  circum- 
ftances  :  and,  in  proportion  as  thefe  appearances  diminifli,  the 
ilrong  and  otfenfive  odour  is  fucceeded  by  another  which  is 
fainter  and  milder,  and  the  mafs  becomes  dry.  The  internal 
part  ftiil  exhibits  the  vegetable  ftru£lurc,  when  the  flem  is  folid 
and  the  fibrous  mutter  has  been  the   predominating  principle  ; 


Vegetable  Mould.  539 

and  It  then  conftitutes  manure  or  foil.  Hence  it  arifes  that  the 
herbaceous  plants  of  a  loofe  texture,  and  abounding  in  juices 
are  not  capable  of  forming  manure  by  their  decompofition,  but 
are  reduced  into  a  brown  mafs  of  little  confidence,  in  which 
neither  fibre  nor  texture  are  obferved  ;  and  this  is  what,  for 
the  moil  part,  forms  vegetable  oiould. 

Vegetable  mould  ufually  conftitutes  the  firft  covering  or  flra- 
tum  of  our  globe  ;  and  in  fuch  cafes  wheretn  it  is  difcovered  at 
a  depth  in  the  earth,  there  is  no  doubt  but  it  has  been  buried 
by  fome  revolution. 

When  a  vegetable  is  converted  Into  earth  by  this  tumultuous 
fermentation,  it  (Hll  retains  the  remains  of  the  vegetable  mixed 
and  confounded  with  the  other  folid  earths  and  metaljick  pro- 
ducts ;  and  by  diftillation  it  affords  oil,  nitrogene  gas,  and  of-  , 
ten  hydrogene.  It  may  therefore  be  conlidered  as  an  inter- 
mediate fubftance  between  crude  and  organick  bodies,  which 
participates  of  the  inertia  of  the  one,  and  the  a6livity  of  the  o- 
ther  ;  and  which  in  this  Itate  is  (till  fubjeft  to  an  infenCble  fer- 
mentatioi),  that  changes  its  nature  ftill  more,  and  deprives  it  of 
all  its  organick  contents.  Thefe  remains  of  vegetables  ftill  con- 
tained in  vegetable  earth,  ferve  as  food  for  other  plants  that 
may  grow  in  it.  The  infenfible  progrefs  of  fermentation,  and 
the  fudlion  of  vegetables,  impoyerifh  the  vegetable  earth,  deprive 
it  of  all  its  organick  matter  and  there  remain  only  the  earths  and 
metallick  refidue  which  form  the  ftjff  poor  foils  and  ochres  when 
the  ferruginous  principle  is  very  abundant. 

As  this  muddy  earth  is  a  mixture  of  all  the  primitive  earths, 
and  fome  of  the  metals  which  are  the  produ<3;  of  vegetation,  as 
well  as  the  oils,  the  falts,  and  other  prod uQs  we  meet  with  ia 
it  ;  w^e  may  confider  it  as  the  refidue  of  the  vegetable  decompo- 
fition,  as  the  great  agent  and  means  by  which  nature  repairs  the 
continual  loffes  the  mineral  kingdom  undergoes.  In  this  mix- 
ture of  all  the  principles  the  materials  of  all  compounds  exift  j 
and  thefe  materials  are  fo  much  the  more  difpofed  to  enter  into 
combinations,  as  they  are  in  a  more  divided  or  difengaged  ftate. 
It  is  in  thefe  earths  that  we  find  diamonds,  quartz-cryltals,  fpars, 
gypfum,  &c.  It  is  in  this  martrix  that  the  bog  ores,  or  ochre- 
pus  ores  of  iron,  are  formed  ;  and  it  appears  that  nature  has  rc- 
ferved  the  impoveriflied  refidue  of  vegetables  for  the  reproduc- 
tion or  reparation  of  the  earthy  and  metallick  fubflances  of  the 
globe,  while  the  organick  remains  are  made  to  ferve  as  nouriflv- 
n^?nt  for  the  growth  of  other  Cucceeding  vegetables. 


PART  THE  FIFTH. 
CONCERNING  ANIMAL  SUBSTANCES. 


INTRODUCTION. 


T 


HE  abufe  which,  at  the  commencement  of  this 
century,  was  made  of  the  application  of  chemiftry  to  medicine, 
occafioned,  a  fiiort  time  afterwards,  that  all  the  relations  be- 
tween the  fcience  and  the  art  of  healing  were  miftaken  and 
rejed^ed.  It  would  no  doubt  have  been  more  prudent,  as  well 
as  more  ufeful,  to  have  connected  thefe  miftaken  applications  : 
but  chemiftry  was  not  perhaps  at  that  time  in  a  fufjiciently  ad- 
vanced ftate,  to  be  advantageoufly  applied  to  the  phenomena  of 
living  bodies  ;  and  even  at  this  day,  we  fee  that,  though  the  phy-r 
fiology  of  the  human  body  is  enriched  with  various  interefting 
fa£Vs,  there  is  ftill  much  to  be  done  before  they  will  be  fuffir 
ciently  numerous  to  exhibit  a  fatisfad:ory  mafs  of  doctrine. 

The  imperfedl  fuccefs  of  chemiftry  in  that  branch  of  the 
fcience  which  has  the  ftudy  of  man  for  its  object,  arifes  from 
the  very  nature  of  the  fubjedl  itfelf.  Some  chemifts,  by  confid- 
ering  the  human  body  as  a  lifclefs  and  paffive  fubftance,  have 
fuppofed  the  humours  to  undergo  the  fame  changes  as  they 
would  have  been  fubjedl  to  out  of  the  body  ;  others  from  a  ve- 
ry fuperficial  knowledge  of  the  conftitution  of  thefe  humours, 
have  pretended  to  explain  ail  the  phenomena  of  the  animal  econ- 
omy. All  have  miftaken  or  overlooked  that  principle  of  life, 
which  inceflantly  a£ls  upon  the  folids  and  fluids  ;  modifies, 
without  ccafing,  the  impreffion  of  esternal  objeds  ;  impedes  the 
degenerations  which  depend  on  the  conftitution  itfelf  ;  and  pre- 
fents  to  us  phenomena  which  chemiftry  never  could  have  known 
or  predicted  by  attending  to  the  invariable  laws  obferved  in  in- 
animate bodies.  " 

None  of  the  bodies  of  the  mineral  kingdom  are  governed  by 
an  internal  force.  They  are  all  fubjecfted  to  the  direct  adlion  of 
foreign  fubftances,  without  any  modification  from  any  vital  prin- 
ciple ;  and  the  air,  water  and  fire,  produce  in  them  the  effeOs 
which  are  neceflary,  conftant,  and  fubjecl  to  calculation  j 
whence  it  happens  that  we  are  able  to  determine,  modify*  and 


Of  Animal  Bodies,  5  4 1 

vary  the  aftion  of  thefe  various  agents  at  pleafure.  It  Is  not  the 
fame  with  living  bodies  ;  they  are  all  indeed  fubje£l  to  the  influ- 
ence of  external  bodies  •,  but  the  the  effect  of  thefe  is  modified 
by  the  reaction  of  the  vital  principle,  and  is  varied  according  to 
the  difpofition  of  that  principle.  The  chemift  cannot  therefore 
determine  the  efFefbs  a  priori^  and  in  a  general  way.  He  muft 
fearch  for  his  refults  rather  in  the  living  body  itfelf  than  in  the 
operations  of  his  laboratory  \  and  can  have  no  affiltance  from 
his  analyfis  but  in  afcertaining  the  nature  of  their  component 
parts.  But  their  adlion,  etfeCls,  or  tranfpofitions,  can  only  be 
known  by  a  ferious  ftudy  of  the  functions  of  the  living  body. 
Chemiftry  can  perform  every  thing  in  the  mineral  kingdom, 
becaufe  every  thing  depends  on  the  laws  of  the  affinities.  But, 
in  the  kingdoms  of  organized  beings,  this  fcience  is  fubordinate 
to  the  laws  of  the  economy  of  living  bodies  ;  and  its  refults  can 
only  be  affirmed  to  be  true,  when  they  are  confirmed  by  obfer- 
vation. 

The  more  the  functions  of  the  Individual  are  Independent  of 
organization,  the  lefs  is  the  empire  of  chemiftry  over  them,  be-^ 
caufe  the  efFedfs  are  modified  in  a  thoufand  ways  ;  and  it  Is 
this  which  renders  the  application  of  chemical  principles  to  the 
phenomena  of  the  human  body  fo  very  difficult ;  for  the  or* 
ganization  Is  not  only  very  complicated,  but  the  efFe£ls  are  con^ 
tinually  varied  by  the  powerful  influence  of  the  mind. 

There  Is  not  however  any  fundlion  in  the  animal  economy, 
upon  which  the  fcience  of  chemiftry  cannot  throw  fome  light. 
If  we  confider  them  in  the  healthy  ftate,  we  ihall  perceive  that 
every  organ  produces  fome  change  in  the  humours  It  receives  5 
and  though  the  chemift  may  indeed  be  Ignorant  of  the  manner 
in  which  fuch  changes  are  produced,  it  is  by  his  art  alone  that 
the  difference  between  the  original  fluid,  and  that  which  has 
been  elaborated,  can  be  afcertained.  Be  fides  which,  the  func- 
tions of  the  various  organs  are  exercifed  upon  external  obje£ts, 
and  thefe  objeds  come  under  the  confideration  of  chemiftry. 
We  are  at  prefent,  for  e^iample,  acq^uainted  with  the  nature  of 
the  air  which  ferves  for  refpiration,  its  effeifls  on  the  lungs, 
and  its  Influence  on  the  animal  economy.  We  are  even  now 
able  to  determine  whether  any  air  be  good  or  bad,  and  know 
how  to  correal  that  which  is  vitiated,  &c.  We  likewife  pofTefs 
fome  accurate  ideas  of  the  nutritive  principle  of  certain  fubftan- 
ces ;  and  chemiftry  teaches  us  how  to  difpois  of  the  refpeftive 
aliments,  and  adapt  them  to  the  various  clrcumftances.  The 
analyfis  of  waters  is  fufficiently  perfecl  to  admit  of  our  diftin- 
guiftiing  the  pYoperties  of  that  fluid  relative  to  health,  and  to 
\<\%^  the  beft  fpr  our  own  vifc ;  fo  that,  while  the  principle  of 


54'2  ^  Animal  Bodies* 

life  prefidcs  over  and  governs  all  the  internal  operations  of  the 
human  body  by  a  mechanifm  which  is  very  imperfefily  known  to 
us,  we  fee  neverthelefs  that  all  the  functlions  receive  an  impreffion 
more  or  lefs  diredl:  from  external  objeds ;  that  all  the  materials 
iifed  for  the  fupport  of  the  machine  are  fupplied  from  without ; 
that  principle  of  life  which  colleds  and  difpofes  of  the  materials, 
after  laws  unknown  tous,  is  capable  neither  of  chooGng  nor  reje6l- 
ing  them  ;  and  that  the  functions  would  be  very  fpeedily  altered, 
if  chemiftry,  founded  on  obfervation,  were  not  careful  to  remove 
the  noxious,  and  felecl  fuch  bodies  as  are  of  advantage  to  ,  the 
fyftem.  Chemiftry  therefore  can  do  nothing  in  the  arrange, 
ment  of  the  materials,  but  poflefles  unlimited  power  in  their  fe- 
ledlion  and  preparation. 

When  the  organization  Is  deranged,  this  defe£l  of  order  can 
arife  only  from  external  or  internal  caufes.  In  the  firft  cafe,  the 
analyfis  of  the  air,  the  water  and  the  food,  will  afford  accurate 
notions  fufficient  to  re-eflablifh  the  fundtlons.  In  the  fecond 
the  chemical  examination  of  the  humours  may  afford  informa- 
tion fufficient  to  dire£l  the  phyfician  in  pointing  out  the  mod 
fuitable  remedy.  Sometimes  the  humours  are  decompofed  in 
the  body,  as  in  vitro.  We  obferve  all  the  phenomena  of  a  de-r 
generation  and  complete  difunion  of  the  principles  which  com- 
pofe  the  blood,  in  the  fcurvy,  cachexy,  malignant  fevers,  &c. 
It  feems  as  if,  in  fuch  cafes,  the  vital  principle  abandoned  the 
government,  and  left  the  folids  and  fluids  to  the  deftru£live  ac- 
tion of  external  agents  ;  in  confequence  of  which  they  become 
decompofed  in  the  fame  maner  as  they  ufually  do  when  feparat- 
ed  from  the  body. 

When  the  principle  of  animality  is  once  extingulflied,  the 
fame  caufes  which  maintained  the  functions,  and  whofe  effe<!:ls 
were  modified  by  that  principle  of  life,  now  acl  with  their 
whole  energy  on  the  body,  and  decompofe  it.  Chemiftry  has 
difcovered  methods  of  extrafting  from  thefe  dead  bodies  a  vari- 
ety of   fabftances  of  «fe  in  the  arts  and  in  pharmacy. 

Chemiftry  is  therefore  applicable  to  the  animal  economy  in 
the  ftate  of  health  and  in  the  ftate  of  ficknefs. 

The  chemical  art  has  marked  the  limits  between  vegetable 
and  animal  fubftances.  Thefe  laft  afford  ammoniack  by  putre- 
fa6tion, -while  the  fermentation  of  the  former  developes  ardent 
fpirit.  The  latter  leave  a  coal  vvhich  burns  eafily  ;  v/hile  the 
former  become  converted  into  a  coal  almoft  inccmbuftible.  An- 
imal matters  contain  much  nitrogene,  which  may  be  difengaged 
by  means  of  nitrick  acid.  The  interefting  Memoirs  of  Meff. 
BerthoUct  and  De  Fourcroy  on  animal  fubftances,  may  be  coi|* 
falted  to  great  advantage. 


bigeftion.     Gafirick  Fluid.  54 j 

GHAPTER    r. 

Concerning  Digeftion. 

THAT  humour  which  is  known  by  the  name  of  the  Gaftrick 
Juice,  is  feparated  by  glands  placed  between  the  membranes 
which  Hne  the  ftomach  ;  and  from  thefe  it  is  emitted  into  the 
ftomach  iifeif. 

In  order  to  obtain  the  gaftrick  juice  in  a  ftate  of  purity,  the 
animals  intended  to  furnifh  it  are  kept  fading  for  two  days,  after 
which  the  (lomaeh  is  extra6led.  In  this  manner  Spallanzani 
obtained  thirty  feven  ounces  of  this  juice  out  of  the  two  firft 
flomachs  of  a  fheep.  The  fame  naturalift  caufed  animals  to 
fwallow  thin  tubes  of  metal,  pierced  with  feveral  holes,  into 
which  he  had  put  fmall  fponges,  very  clean  and  dry.  He  cauf- 
ed crows  to  fwallow  eight  at  a  time,  which  were  vomited  up  at 
the  end  of  three  hours  and  a  half.  The  juice  which  he  obtain- 
ed was  yellow,  tranfparent,  fait,  bitter,  and  leaving  very  Mttle 
fediment,  when  the  bird  was  fading.  The  gadrick  juice  may 
likewife  be  procured  by  the  vomiting  which  is  excited  by  irri- 
tation during  fading.  M.  Scopoli  has  obferved  that  the  moPc 
fluid  part  only  is  thrown  up  by  irritation;  and  that  the  thicker 
part  does  not  quit  the  domach  but  by  the  alfidance  of  an  emet- 
ick.  M.  Gode,  who  had  long  accuftomed  himfelf  to  fwallow 
the  air,  which  anfwered  the  purpofe  of  an  emetick  with  him, 
has  availed  himfelf  of  this  habit  to  make  fome  experiments  with 
the  gadrick  juice.  He  fufpends  his  refpiration,  receives  air  into 
his  mouth,  and  puOies  it  towards  the  pharinx  with  his  tongue. 
This  air,  rarefied  in  his  domacli,  produces  a  convulfive  motion, 
which  clears  it  of  its  contents.  Spallanzani  has  obferved  thac 
eagles  fpontaneoudy  emit  a  confidcrable  quantity  of  gadrick 
juice,  when  fading  in  the  morning. 

We  are  indebted  to  Reaumur  and  the  abbe  Spallanzani  for 
very  intercding  experiments  refoefling  the  virtue  and  cfFe£^s  of 
the  gadrick  juice  in  digedion.  They  caufed  animals  to  fwallow 
tubes  of  metal,  perforated  in  various  places,  and  ^Wtd  v/ith  ali- 
ments, to  examine  their  efFe6ts.  '\^h&  philofopher  of  Pavia  u- 
fed  parfes  of  thread,  and  ba;';s  of  linen  and  of  woollen.  He 
hiinfelf  f^vallowed  fmall  purfes  filled  with  flefh  boiled  or  raw, 
with  bread  madicated,  and  alfo  in  its  original  flate,  &c.  and 
likewife  fmall  cylinders  of  wood,  five  lines  in  length  and  three 
in  diameter,  pierced  with  holes,  and  covered  with  cloth. 

M.  GofTe,  avaiUng  himfelf  of  the  facility  with  which  he  was 
able  to  vomit  by  means  of  the  air,  has  taken  all   kinds  of  food 


5*44  ^^^  Gnjrlck  Juia. 

and  examined  the  changes  they  had  undergone,  by  returning 
them  at  intervals  more  or  lefs  remote  from  the  time  of  deglutition. 

From  thefe  various  experiments  it  follows — i.  That  the  gaf- 
trick  juice  reduces  the  aliments  into  an  uniform  magma,  even 
out  of  the  body,  and  in  vitro  ;  and  that  it  ads  in  the  fame  man- 
ner on  the  ftomach  after  death  :  which  proves  that  its  effed:  is 
chemical,  and  aimoil  independent  of  vitality.  2.  That  the  gaf- 
trick  juice  effe£ts  the  foJution  of  the  aliments  included  in  tubes 
of  metal,  and  confcquently  defended  from  any  trituration. 
3.  That  though  there  is  no  trituration  in  membraneous  ftom- 
achs,  this  a6lion  powerfully  affifts  the  efFe<Sb  of  the  digeftive 
juices  in  animals  whofe  ftomach  is  mufcular,  fuch  as  ducks, 
geefe,  pigeons,  &c.  Some  of  thefe  animals  bred  up  with  fuffi- 
cient  care  that  they  might  not  fwallow  ftones,  have  neverthelefs 
broken  fpheresand  tubes  of  metal,  blunted  lancets,  and  rounded 
pieces  of  glafs,  which  were  introduced  into  their  ftomachs. 
M.  Spallanzani  has  afcertained  that  flelh  included  in  fpheres  fuf- 
ficiently  ftrong  to  refift  the  mufcular  aftion,  was  completely  di- 
gefted.  4.  That  the  gaftrick  juice  a£fs  by  its  folvent  power, 
and  not  as  a  ferment ;  becaufe  the  ordinary  and  natural  digef- 
tion  is  attended  with  no  difengagement  of  air,  nor  inflation, 
nor  heat,  nor  in  a  word,  with  any  of  the  phenomena  of  fer- 
mentation. 

M.  Scopoli  obferves  very  well  that  nothing  pofitive  or  certain 
can  be  aflerted  refpeding  the  nature  of  the  galtrick  juice.  It  is 
fometimes  acid  and  fometimes  infipid.  M.  Brugnatelli  has  found 
in  the  gaftrick  juice  of  carnivorous  birds,  and  fome  others,  a  dif- 
engaged  acid,  a  refin,  and  an  animal  fubftance,  united  with  a 
fmall  quantity  of  common  fait.  The  gaftrick  juice  of  ruminat- 
nating  animals  contains  ammoniack,  an  extraftive  animal 
fubftance  and  common  fait.  In  our  time  the  phofphorick 
falts  have  been  found  difengaged  in  the  gaftrick  juice. 

It  appears,  from  the  obfervations  of  Meffrs.  Spallanzani  and 
GbfTe,  that  the  nature  of  the  gaftrick  juice  varies  according  to 
that  of  the  aliments.  This  juice  is  conftantly  acid  when  the  di- 
et is  vegetable.  The  abbe  Spallanzani  affirms,  contrary  to 
MeflTrs.  Brugnatelli  and  Carminati,  that  birds  of  prey  have  never 
afforded  him  an  acid  juice  ;  and  he  affirms  the  fame  of  ferpents, 
frogs,  fifties,  &c. 

In  order  to  fiiew  clearly  that  there  is  a  great  difference  be- 
tween the  gaftrick  juices  of  various  animals,  it  is  fufficient  to  ob- 
ferve  that  the  gaftrick  juice  of  the  kite,  the  falcon,  &c.  does  not 
difTolve  bread,  though  it  digefts  flefh  meat ;  and  that  the  gaftrick 
juice  of  the  turkey,  the  duck,  &c.  has  no  a£lion  upon  fleffi, 
but  converts  the  hardeft  grain  into  a  pulp. 


Properties  of  Milk.  545 

Meffrs.  Jurine,  Toggia,  and  CarminatI,  have  made  the  moft 
fuccefsful  applications  of  the  gaftrick  juiee  in,  the  treatment  of 
Avouiids. 

CHAPTER    11. 

Concerning  Milki 

OF  all  the  animal  humours,  milk  is  beyond  contradi«SlIoii  ths 
lead  animaiiz^d.  It  appears  to  partake  of  the  nature  of  chyle ; 
it  preferves  the  qualities  and  character  of  the  aliments  \  and  for 
this  reafon  we  are  induced  to  place  it  at  the  head  of  the  hu- 
JTiours  of  animal  bodies. 

Milk  is  feparated  in  organs  called  breads  or  udders  -,  and 
though  the  clafs  of  animals  with  breads  exhibits  the  greateft, 
ianalogy  in  the  internal  conftrucSlion  of  thefe  organs,  yet  the  milk 
Varies  in  the  feveral  fpecies.  In  the  human  fpecies  it  is  more 
faccharine  ;  in  the  cow,  milder  or  fofter  :  the  milk  of  the  goat> 
and  of  the  afs,  are  flightly  aftringent ;  and  it  is  for  this  reafon 
that  they  are  ordered  to  be  taken  in  diforders  which  have  weak- 
ened and  exhaufted  the  human  frame.* 

Milk  is  the  firft  food  of  young  animals.  Their  weak  and  fee- 
ble ftomachs  are  incapable  of  digefting  and  aflimilating  aliments 
afforded  by  the  earth  ;  and  nature  has  accordirigly  pi-ovidcd 
them  a  food  more  animalized,  and  confequently  more  anala- 
gous  to  their  ftrudure,  until  their  iucreafed  ftrength  permits 
them  to  ufe  a  coarfer  food. 

Hunter  has  obferved  that  ail  the  animals  which  difgofge  to 
feed  their  young,  have  glands  in  the  ftomach,  which  are  formed 
during  the  incubation,   and  afterwards  gradually  obliterated. 

Milk  is  in  general  of  an  opaque  white  colour,  and  faccharine 
tafle. 

^^  It  iTecms  moft  probable  that  the  pre-emine^nce  flill  given  to  the  milk 
of  the  afs,  arifes  from  no  ly-'tter  rcalon  than  the  loud  and  fororcus  voice 
of  the  anirnal  v/hich,  by  a  kind  ot  reafoning  very  common  among  the  ;)n- 
cient  phyficians,  has  kd  to  a  conclufion  that  the  milk  of  fuch  a  cr^:alu^e 
niuftbe  good  for  the  lungs.  The  root  fatyrion,  the  milk  of  the  goat,  anci 
many  other  fubftances,  formerly  Oood  high  in  medical  cftimatipn,  fcrrea- 
fons  equally  obvious  and  equally  fuperficial.  It  muft  not  however  be  de- 
fied but  that,  when  the  polTeflbr  of  an  exhaufted  cotiftitiition  becomes  lo 
far  obedient  to  advice  as  regularly  to  take  alfes  milk,  and  attend  to  oth^r 
circumflances  of  regimen,  he  may  find  himitif  bentijicd  ;  and  the  «{k  ■- 
milk,  merely  as  milk,  fubllituted  infteau  of  fome  lefsfrienc]\  bevci^^^q,:  o; 
food,  ma?  be  entijcd  m  a  fhan;  in  th.:  prcner;:!  eiFec"^.     1\ 


54^  Add  of  MUL 

oy-  atteadiTT  to  the  various  alter^itlons  it  undergoes  when  left 
to  itfelf,  or  wheti  decompofcd  by  cht-mical  agents,  we  may  ar- 
rive at  a  perfect  knowledge  of  its  nature. 

Milk  expofed  to  the  air  is  decompofed  in  a  lon^^er  or  (horter 
time,  according  to  the  degree  of  heat  of  the  atmoiphere.  But 
if  the  temperature  of  the  atmofphere  be  hot,  and  the  milk  in 
larc^c  qii.intity,  it  may  pafs  to  the  fpirituous  fermentation. 
Mirco  Folo,  the  Venetian  who  wrote  in  the  thirteenth  century, 
ainrms  that  the  Tartars  drink  mares  mi!k,  fo  well  prepared  that 
it  might  be  taken  for  white  wine.  Claude  Strahclenbcrg  re- 
ports that  the  Tartars  extract  a  vinous  fpirit  from  milk,  which 
they  call  Arki  (Defciiption  de  I'Empire  de  RufTie.)  John 
G^oriTe  Gmelin,  in  his  Voyage  to  Siberia,  affirms  that  the  milk 
is  fufFjred  to  become  four,  and  is  afterwards  diftilled. 

M.  Nicolas  Oleretflcowiky,  of  St.  Peterfburgh,  has  proved — 
I.  That  milk  deprived  of  i^s  cream  cannot  produce  ardent  fpiri^, 
either  with  a  ferment  or  without  2.  That  milk  agitated  in  a 
clofe  velltd  affords  ardent  fpirit.  3.  That  fermented  milk  lofes 
its  fpirituous  principle  by  heat,  and  paffes  to  the  (late  of  vinegar. 
Joun^al  de  Phyf.  1779. 

Mj;k  becomes  four  in  the  fummer,  and  in  three  or  four  days 
the  acid  has  acquired  its  ftrengih.  If  the  whey  be  then  filtered, 
and  evaporated  to  half,  cheefe  is  depofited.  If  it  be  again  filter- 
ed, and  a  fmall  quantity  of  the  tartareous  acid  be  added,  a  quan- 
tity of  fnall  cryitals  of  tartar  are  feen  to  be  formed  in  the  courfe 
of  an  hour  afrer wards,  which  according  to  Schesle  can  (not) 
ariie  only  from  the  fmall  quantity  of  muriate  potafh  (in  milk, 
but  from  an  effential  fait*)  wliich  milk  always  contains. 

f  o  feparate  the  various  principles  contained  in  four  whey, 
the  fqilowing  procefs  may  be  ufed,  which  was  pointed  out  by 
the  celebrated  Scheele. 

Evaporate  tlie  four  milk  to  one  eighth.  All  the  acid  f<:-p.ira^e-, 
a  id  reina'ns  on  the  iiltre.  Pour  lime  water  on  the  reHdue  ;  an 
earth. is  precipitated,  and  the  lime  combines  with  the  acid. 
The  lime  may  be  difplaced  by  the  oxalick  acid,  which  forms 
with  it  an  infoiuble  oxalite,  which  falls  down,  and  the  acid  of 
milk  remains  difengaged.  The  fluid  is  then  to  be  evaporated 
to  the  confiflence  of  honey,  and  upon  this  very  pure  alcohol  is 
to  be  poured.  The  fugar  of  milk,  and  all  the  other  principles, 
a<-e  infoiuble,  except   the  acid.      The  mafs  being  then  filtered, 

*  The  wr)rd^  in  the  pare'ithef^s  are  addid,  to  render  the  text  conform- 
able to  Scheele's  Eflay.     T. 


Sugar  of  Milk. 


547 


the  acFd  of  milk  may  be  feparatcd  from  its  folventby  difliilation. 
This  is  the  acid  known  by  the  name  of  Ladick  Acid.  It  pof- 
lefles  the  following  charaders. 

1.  When  faturated  with  potafh,  it  affords  a  deliquefcent  fait, 
ifoluble  in  alcohol. 

2.  With  foda,  a  fait  not  cryftallizable,  and  foluble  in  alcohol. 

3.  With  ammoniack,    a  deliquefcent  fait,    which  iuffers  molt 
of  its  alkali  to  efcape  before  the  heat  has  dedroycd  the  acid. 

4.  Barytes,  lime,   and  alumine,  form  u  ith  it  falls  which  are 
i^eliquelcent. 

5.  Magnefia  affords  fmall  cryftals,    which  are  refolved  into  ^ 
,  liquor. 

6.  Bifmuth,  cobalt,  antimony,  tin,  mercury,  fdver,  and  gold, 
arc  not  attacked  by  either  hot  or  cold. 

7.  It  diffolves  iron  and  zinc,   and  produces  hydrogenous  gas. 
^The  folution  of  iron  is  brown,  and  does  not  afford  cryftals  :  that 

>f  zinc  cryftailizes. 

8.  With  copper  it  affumes  a  blue  colour,  which    changes   to 
[reen,  and  afterwards  to  an  obfcure  brown,  without  cryiiallizing. 

9.  When  kept  in  digeffion  upon   lead   for  feveral  days  it  dif- 
Folves  it.     The  folution  does  not   afford  cryftals.     A  light  f-di- 

lent  of  a  white  colour  is  formed,  which  Scheele  confiders  as  a 

fulphateof  lead. 

Whey  not  four  contains  a  faline  fubftance,  known  by  the  name 
)f  Sugar  of  Milk.     Meffrs.  Valgamoz  and  Lichtenflem  have  de- 

[cribed  the  procefs  ufed  to  obtain  this  faline  fubftance.  The 
liik  is  deprived  of  its  cream  in  the  ufual  manner,  and  of  its 
;urd  by  runnet.  It  is  then  concentrated  by  evaporation  till  it 
las  acquired  the  confillence  of  honey,  after  which  it  is  put  into 
loulds,  and  dried  in  the  fun.  This  is  called  Sugar  of  Milk  in 
^akes  (fucre  de  lait  en  tablettes.)       Thefe  cakes  are  diffolved  in 

ivater,  clarihed  with  white  of  egg,  evaporated  to  the  confillence 
Rof  fyrup,  and  fet  to  cryitallize  in  a  cool  place.     It  affords  v.'hiic 
Tviialsin  rhomboidal  parallelopipedons. 
Sugar  of  milk  has  a  llightly    faccharine  tafte,  infipid,   and  as 

it  were  earthy.  It  is  fcluble  in  three  or  four  pints'"  of  hot  wa- 
IX.  Mr.  Rouclle  obtained  from  twenty-four  to  thirty  grains  of 
dties  from  one  pound  of  this  fall  burned.       Three  fourths  con. 

fjUed  of  muriate  of  potafli,  and  the  reft  was  carbonate  of  pot- 
lih. 


*  By  an  ovcrflght  for  r,a&ts.     T. 


54 5  Coagulaiion  of  Milh, 

Sugar  of  milk  exhibits  the  fame  appearances  as  fugar,  either 
by  diltiliation,  or  on  the  fire.  This  fait,*  treated  with  the  ni-. 
trick  acid,  afforded  me  three  gros  of  oxalick  acid  in  the  month 
of  July,  1787.  ( Memoir  prefente  a  la  Societe  Royaie  des  Sciences 
de  Montpellier.)  Scheele  obferved  the  fame  facl  nearly  at  the 
fame  time.  1  obtained  it  ;n  beautiful  cryftals  -,  gcheele,  in  the 
form  of  a  white  powder.f 

If  fix  fpoonfuls  of  good  alcohol  be  mixed  with  three  pints  of 
milk,  and  the  mixture  be  expofed  to  heat  in  clofe  veffeis,  with 
the  attention  to  give,  from  time  to  time,  a  flight  vent  to  the  gas 
of  the  fermentation  ;  the  milk  is  found,  in  the  courfe  of  a 
month,  to  be  changed  into  good  acetous  acid,  according  to 
Scheele. 

If  a  bottle  be  filled  with  frefh  milk,  and  inverted  beneath  the 
furface  of  milk  in  an  open  veflel,  and  this  be  fubjefted  to  a  de- 
gree of  heat  a  Httle  exceeding  that  of  fummcr,  at  the  end  of 
twenty-four  hours  the  milk  is  found  to  be  coagulated  5  the  gas 
which  is  developed  difplaces  the  milk  :  a  proof  according  to 
Scheele,  that  the  vinous  fermentation  has  taken  place. 

To  decompofe  milk,  and  feparate  its  various  conltituent  parts, 
rennet,  or  the  milk  turned  four  in  the  llomach  of  calves,  is  com- 

^  The  quantity  of  fait  ufedis  not  put  down.  Scheele  obtained  five  drachms 
of  acid  of  iugar  in  long  cr\ftd!s,  by  diitiliing  nkrovis  ac'd  from  twelve 
ounces  of  fugar  of  milk  and  feven  drachms  and  a  hall  of  the  peculiar  acid 
o?  SUGAR  OF  MILK  in  a  white  powder.  The  memoir  of  Scheele  is  dated 
1780.    T. 

f  J  do  not  lee  by  what  overfight  it  is  that  our  ingenious  author  feems  to 
confufe  ther^o  fafts  together,  which  are  afforded  by  treating  the  fugar  of 
milk  with  nitrous  acid.  One,  as  obferved  in  the  preceding  note,  is  the  0x1 
alick  orfaccharine  acid,  and  tlie  other  the  acid  cf  fugar  of  milk.  The 
properties  of  the  laft  (Scheele's  Eflays,  London,  1786)  are  the  following  : 

1.  It  is  combuftible  like  oil  in  a  red-hot  crucible,  without  leaving  any 
mark  of  afhes  behind,  a.  Sixty  parts  of  boiling  v/ater,  or  eighty  of 
cold  water,  are  required  to  diffolve  it.  3.  Its  tafte  is  fourilh,  it  reddens 
tin<5ture  oHitmus,  and  efferyefces  with  chalk.  4.  By  deilrudive  dillilla- 
tion  it  melts,  grows  black,  froths  very  much  ;  a  brown  fait,  fmelling  like  a 
mixture  of  flowers  of  benzoin  and  acid  of  amber,  fublimes  ;  a  brown  li- 
quid, without  any  appearance  of  oil,  comes  over  into  the  receiver,  and  is 
found  to  c  >Ptain  fome  of  the  fame  kind  of  fait  as  was  fublimed.  The  fub- 
limed  fait  is  aci_d>  ealily  foluble  in  ardent  fpirit,  but  more  difficultly  in  wa- 
ter and  burns  in  the  fire  with  a  flame.  5.  Whh  all  the  foJuble  earths  it 
forms  faitsinfoluble  in  w;Uer.  6.  With  vegetable  alkali  it  forms  a  peifed- 
ly  neutral  cryftallizable  falt,foluble  in  eight  times  its  weight  of  boilmg  war 
ter,  and  feparable  for  the  moft  part  by  cooling.  7.  With  mineral  al]<a!i  it 
forms  a  fait  which  lequires  only  five  parts  of  boiling  water  for  its  folution. 
S.  With  volatile  alkali  it  forms  a  fait  which,  after  being  gently  dried,  has 
aVouriOi  talle.  9.  It  does  not  perceptibly  aft  on  the  mctaJs  j  but  forms, 
with  their  calces,  falts  of  very  difficult  folubility,  which  therefore  f4 
ddwn,    Tv   ■ 


Coagulation  of  Miih,  54^ 

inonly  made  ufe  of.  For  this  purpofe  the  milk  is  warmed,  an4 
twelve  or  fifteen  grains  of  rennet  is  added  to  each  pint.  GaU 
lium,  the  flowers  of  thiflle  or  artichokes,  and  the  internal  mem* 
brane  of  the  ftomach  of  birds  dried,  and  reduced  to  powder, 
&c.  are  among  the  fubltances  which  may  be  ufed  to  turn  milk. 
The  whey  obtained  in  this  manner  is  turbid  ;  but  may  be  clari- 
fied by  boiling  it  with  white  of  egg,  and  fubfeqqent  filtration. 

On  the  mountain  of  Larzac  1  have  feen  the  dairy  woman 
plunge  her  arms  up  to  the  elbows  in  the  milk,  and  change  their 
place  from  time  to  time.  This  was  done  with  a  view  to  haften 
the  feparation  of  the  principles  ;  and  it  is  probable  that  the  heat, 
and  perhaps  pertain  emanations  from  the  arm  itfelf,  might  favour 
that  effeiSl:. 

The  folid  mafs  which  feparates  from  whey,  contains  two  other 
fubftances  very  interefling  to  be  known  j  namely  cheefe  and 
butter. 

If  any  vegetable  or  mineral  acid  l)e  put  into  milk,  a  coagula- 
tion follows  as  is  well  known.  The  only  difference  is,  that  the 
mineral  acid  affords  lefs  cheefe  or  curd  than  the  vegetable  ;  and 
the  various  fubftances  ufed  to  coagulate  milk,  may  perhaps  aft 
merely  by  virtue  of  the  acid  they  contain.  Olaus  Borrichius 
obtained  no  acid  from  curdled  milk  ;it  a  degree  of  heat  incapable 
of  decompofing  it.  The  coagulum  which  is  afforded  in  all  thefe 
cafes,  contains  a  fubflance  of  the  nature  of  gluten,  which  forms 
the  cheefe  ;  and  another  fubltance  of  the  nature  of  oils,  which 
forms  the  blotter.  When  cheefe  is  prepared  for  the  table,  the 
butter  is  not  feparated,  becaufe  it  renders  it  milder  and  more 
agreeable. 

The  cauftick  alkalis  difTolve  cheefe  by  the  afTiftance  of  heat. 
But  it  is  not  held  in  folurion  by  an  alkali  in  milk. 

If  one  part  of  cheefe  newly  feparated,  and  not  dried,  be  mix- 
ed with  eight  parts  of  water  flightly  acidul^ited  by  a  mineral  acid, 
and  the  mixture  be  boiled,  the  cheefe  will  be  difTolved,  though 
it  would  not  have  been  f^nfibly  acled  on  by  a  vegetable  acid. 
This  is  the  caufe  why  the  vegetable  acids  feparate  a  mych  great* 
cr  quantity  of  curd  from  the  faipe  quantity  of  milk  than  the 
mineral  acids  do. 

The  caufe  why  falts,  gums,  fugar,  &c.  coagulate  milk,  may 
be  deduced  from  the  greater  affinity  of  the  water  with  thefe 
bodies  than  with  the  cheefj. 

The  earth  of  cheefe  is  a  phofphate  of  Hme,  according  to 
Scheele. 

No  fubflance  has  a  flronger  refembhncc  to  cheefe  than  the 
-white  of  egg  boiled.  White  of  egg  is  diiTolved  in  diluted  acid, 
and  alio  in  cauftick  alkali,  and  in  jime  water,  and  i»  precipitated 
from  them  by  acids. 


55C>  '  Cheefe,     Butter. 

Scheele  thinks  that  the  coagulation  cf  white  of  egg,  lymph, 
aiid  cheefe,  is  owing  ta  the  combination  of  calorick  ;  and  he 
proves  his  opinion  as  follows  :  Mix  one  part  of  white  of  egg 
with  four  parts  of  water  ;  pour  in  a  firiall  quantity  of  pure  al- 
kali j  add  as  much  muriatick  acid  as  is  ncccflary  to  faturate  it, 
and  the  white  of  egg  will  coagulate.  In  this  experiment  there 
is  a  change  of  principles.  The  heat  of  the  alkali  combines 
with  the  white  of  egg,  and  the  alkali  with  the  muriatick  acid.* 

Ammoniack  diffolves  cheefc  more  effectually  than  lixed  alka- 
lis. If  a  few  drops  be  poured  into  coagulated  miik,  it  quickly 
caufes  the  the  coagulum  to  difappear. 

Concentrated  acids  like  wife  dilTolve  it.  Nitrlck  acid  difenga- 
ges  nitrogene. 

The  curd  dried,  and  placed  in  a  proper  fituation  to  under- 
go a  commencement  of  the  putrid  tcrmenration,  acquires  confift- 
cnce  tafte  and  colour.  In  this  ftaie  it  is  ufed  at  table  by  the 
uameof  Cheefe. 

At  Roquefort,  where  I  have  attended  the  manipulations  of 
the  excellent  cheefe  which  \h  made  there,  care  is  taken  to  prefs 
the  curd  well,  in  order  to  expel  tne  whey,  and  to  dry  it  as  accu- 
rately as  poffible.  After  this  it  is  taken  into  caves,  where  the 
temperature  is  two  or  three  degrees  above  c.  The  fermenta- 
tion is  developed  by  a  fmall  quantity  of  fait.  The  putrefaction 
is  fufpended  by  fcraping  the  iurface  from  time  to  time  ;  and  the 
fermentation  thus  governed  by  art,  and  kept  under  by  thecool- 
nefs  of  tlie  caves,  produces  a'  How  effe£l  upon  all  the  ctieefe,  and 
fuccellively  developes  the  red  and  blue  colours,  of  which  I  have 
given  the  etiology  ui  a  Memoir  on  the  Fabrication  of  Cheefe  at 
.  Roquefort,  prelented  to  the  Royal  Society  of  /Agriculture,  and 
printed  in    the  fouith  volume  of  the  Amiales  Chimiques.^ 

Butter  is  the  third  principle  contained  in  milk.  It  is  feparat- 
cd  from  the  fcum  and  the  cafeous  matter  by  rapid  agitation. 
The   fubilance  called  cream   is  a  mixture  of   cheefe  and  butier 

*  The  renfcning  of  Scheele  is  more  fully  this  : — Heat  coagulntes  white 
of  egg,  without  dmiJijilhing  its  weight :  whence  he  concludes  coiigujatcd 
vhite  of  egg  to  be  a  combi'uiiion  ot  heat  withwhite  of  egg.  Acids  exuel 
teat  from  caultick  alkalis  when  they  combine  with  then.,  but  none  from 
lirJd  alkalis.     A  very  dilute  alkali  is  uled  in  this  txperimcnt,  that  the  rem- 

■  pevi^tUi'e  may  not  be  railed,  and  ncveri.heicfs  the  effect  takes  pkice  ;  but  it 
does  not  when  a  iiiild  alkali  is  iiied.  Whence  he  concludes  thiit  tlie  heat 
of  the  cauflick  aikj'.,  inlxead  ot  being  eaVploycd  to  laife  ihe'teynperature, 

'tas  entered  into  con.binatron  with  the  white  of  tgg,  and  coagiflated  it.   T 

f  It  is  in  the  fouiih  volume  of  tlie  Amudes  r/t-  C/.'hW/^  i\vdt  the  author  has 
inierted  an  cxtraCl  fioni  this  excelieiu  Memoir  on  thio  fubje,:u     T* 


Properties  of  the  Blocd.  55 1 

which  floats  on  fhe  top  of  the  milk.  Violent  agifation  converts 
this  into  froth ;  in  which  (late  it  is  called  whipped  cream. 

Butter  has  a  foft  coafift-ince,  is  of  a  yellow  golden  colour 
more  or  lefs  deep,  of  a  mild  agreeable  llavour,  melts  eafily,  and 
becomes  f  >ild  again  by  mere  cooling. 

Butter  is  eafily  changed,  and  becom'^s  rancid  like  oils.  The 
acid  which  is  developed  may  be  carried  off  by  water,  or  bv  foir- 
i^  of  wine,  which  ddfolve  it.  Fixed  alkali  difTjlves  butter,  and 
forms  a  foap  little  known. 

Di filiation  affords  a  coloured  concrete  oil  from  butter,  and  a 
ftrong  pungent  acid.  This  oil,  by  repeated  diftiiiatioa,  beconaes 
altered,  and  refembles  volatile  oils. 

Miik  is  therefore  a  mixture  of  oil,  lymph,  ferum,  and  fait. 
This  mixture  is  weakly  united,  and  the  union  between  the  pri«- 
ci;->les  is  eafily  dcftroyed.  Milk  is  faid  to  be  turned  when  the 
difunion  of  its  principles  is  effe  Hied  by  mere  repofe  ;  but  whea 
this  feparation  is  made  by  re-agents  it  is  faid  to  be  curdled^  or 
coagulated. 


CHAPTER    III. 

Concerning  the  Blood. 

BLOOD  is  that  red  humour  which  circulates  In  the  human  b»- 
dy  by  means  of  the  arteries  and  veins,  and  fupports  life  by  fup- 
plying  all  the  organs  with  the  peculiar  juices  they  demand.  It 
is  this  humour  which  receives  the  produ^  of  digeflion  from 
the  flomach,  which  it  elaborates  and  animalizes.  This  hu- 
mour is  withreafon  confidered  as  the  focus  of  life.  The  differ- 
ence of  tempsramenrs  with  regard  to  the  paTions,  has  been  at- 
tributed to  it  by  all  the  philofophers  who  have  treated  this  fub- 
je.l.  It  is  in  vain  that  phyficians  have  changed  their  fyftem  ; 
for  the  opinions  of  the  people  have  been  lefs  verfanle,  and  they 
have  continued  to  attribute  all  the  (hides  of  temperament  to  the 
modifications  of  the  blood.  It  is  likewife  to  the  alterations  of 
this  humour  that  pliyGcians  have  for  a  loner  time  afcribed  the 
caufe  of  almofl  every  mdi'ly.  It  is  more  efpecially  entitled  to 
the  attention  of  the  cherr.ilt. 

The  blood  varies  in  thj  fame  individual,  not  only  with  reofard 
to  the  iiate  of  health,  but  likewife  at  the  fa^ne  inltant.  The 
blood  which  circulates  throag'i  the  veins  has  not  the  fame  in- 

*  Lait  tonrnt'  and  hit  cmUS.  T'lis  diHIr.  q;  in  fcarcely  obtains  in  the 
Engiifli  kngu;\ge.     T. 


55*  Pt'operths  of  the  Blood. 

tenfity  of  colciur,  nor  the  fame  confidence,  as  that  of  the 
the  arteries  ;  that  which  flows  through  the  organs  of  the  breaft 
differs  from  that  which  pafles  languidly  through  the  vifccra  o^ 
the  lower  belly. 

The  blood  differs  alfo — i.  According  to  the  age.  In  infancy 
it  is  paler  and  \th  confident.  2.  According  to  the  tempera- 
ment. Sanguln*^  perfoas  h;\ve  the  blood  of  a  vermilion  red  ; 
in  the  phlegmatick  it  is  paler  ;  and  in  thfc  cholerick  it  is  more 
yellow. 

The  temperature  of  the  blood  is  not  the  fame  iri  the  feveral 
fpecies  of  animals.  Some  have  the  blood  hotter,  and  fomc 
colder  than  the  mediurh  in  which  they  live.  Animals  with 
lungs  have  the  blood  redder  and  hotter  than  thofe  which  are 
without  that  organ  ;  and  the  colour  and  heat  are  in  proportion 
to  the  extent  and  perfection  of  the  lungs,  as  M.  BufFon  and 
BroufTonet  have  obferved. 

The  blood  putrefies  by  a  gentle  heat.  If  it  be  didilled  on  the 
water-bath,  it  affords  the  phlegm  of  a  faint  fmell,  which  eafily 
putrefies.  Blood  dried  by  a  proper  heat,  effervefces  with  acids  ; 
if  expofed  to  the  air,  it  attracts  humidity  ;  and  at  the  end  of 
feveral  months  a  faline  efflorefcence  is  formed,  which  Rouelle 
has  afcertained  to  be  foda.  If  the  didillation  of  blood  be  carri- 
ed farther,  the  product  is  acid,  oil,  carbonate  of  ammoniack^ 
&c.  A  fpongy  coal  remains  in  the  retort,  of  very  difficult  in- 
cineration, in  which  are  found  fea  fait,  carbonate  of  foda,  iron, 
and  phofphate  of  lime. 

Alcohol  and  the  acids  coagulate  the  blood  ;  alkalis  render  it 
more  fluid. 

But  if  the  blood  received  in  a  (hallow  bafon  be  obferved,  the 
following  alterations  are  feen  : — -It  firft  becomes  divided  into 
two  very  diftin£l  fubftances,  the  one  liquid,  flightly  greenifli, 
and  called  lymph,  or  ferum  ;  and  the  other  reddilh  and  foHd, 
called  the  fibrous  part  of  the  blood.  It  is  this  feparation  of  the 
blood  which  hascaufed  the  exillence  of  polypi  in  the  larger  vef- 
fels  to  be  credited,  becaufe  concretions  have  been  found  in  thofe 
veffels  after  death.  We  will  feparately  examine  thefe  two  fub- 
ftances. 

Serum  has  a  yellow  colour,  inclining  td  green.  Its  tafte  is 
flightly  faline.  It  contains  a  difengaged  alkali,  turns  fyrup  of 
violets  green,  and  hardens  in  a  moderate  heat,  which  is  the  char- 
after  of  the  lymph.  Serum  diftilled  on  a  water-bath  affords  an 
infipid  phlegm,  neither  acid  nor  alkaline,  but  very  readily  pu- 
trefying. When  this  phlegm  has  paffed  over,  the  refidue  is 
tranfparent  like  horn,  no  longer  foluble  in  v^ater,  and  affording 
by  didillation  an  alkaline  phlegm,  carbonate  of  ammoniack,  aiKl 
«  fetid  biackifli  oil  more  or  lefs  thick  j  the  remaining  coal  in  the 


Properties  of  the  Bloodi  55^3 

fetort  is  very  voluminous,  and  very  difficult  to  incinerate  ;  the 
allies  afFord  muriate  of  foda  and  phofphate  of  lime. 

Serum  eafily  putrefies,  and  then  affords  much  carbonate  of 
ammoniack. 

Serum  poured  into  boiling  water  coagulates  ;  but  it  contains 
a  part  which  is  foluble  in  water,  to  which  it  communicates  a 
milky  colour,  and  all  the  properties  of  milk,  according  to 
Boucquet. 

Alkalis  render  the  ferum  more  fluid,  but  acids  coagulate  it. 
fey  filtering  and  evaporating  the  fluid,  a  nelitral  fait  is  obtained^ 
confining  of  the  acid  employed,  and  foda.  It  appears  therefore 
that  the  lymph  is  kept  in  the  liquid  (late  by  the  predominating 
alkali. 

The  thickened  ferum  affords  mephitis  by  the  riitrick  acid,  af- 
fifted  by  a  flight  heat ;  if  the  fire  be  increafed,  nitrous  gas  is 
difengaged  ;  the  refidue  affords  the  oxalick  acid,  aiid  a  portion 
of  malick  acid. 

Serum  is  coagulated  by  alcohol;  but  the  coagulum  is  foluble 
in  water,  and  in  this  it  differs  much  from  the  coagulum  formed 
by  acids  :  this  difference  depends  on  the  circumftance  that 
the  alcohol  feizes  the  water  which  diluted  the  ferum  ;  whereas 
the  acid  fci^es  the  alkali  which  diffolvcd  it. 

The  clot  or  fibrous  part  of  the  blood  likewlfe  contains  much 
lymph  ;  but  this  may  be  difengaged  by  wafliing.  The  water 
at  the  fame  time  carries  off  the  colouring  matter,  which  con- 
tains much  iron  :  and  this  coagulated  part,  when  well  wafiied, 
forms  a  fibrous  white  fubftance  void  of  fmell  ;  which,  diflilled 
on  the  water  bath,  affords  an  infipid  phlegm,  eafily  fufceptible 
of  putrefa6f  ion.  The  refidue  becomes  very  dry,  even  by  a  gen- 
tle heat  •,  when  fuddenly  expofed  to  a  confiderable  heat,  it 
flirinks  up  like  parchment  ;  but  when  diflilled  in  a  retort  it  af- 
fords an  alkaline  phlegm,  carbonate  of  ammoniack,  oil,  &c.  The 
coal,  which  is  lefs  voluminous  and  lighter  than  that  of  lymph, 
affords  the  phofphate  of  lime  by  incineration. 

The  fibrous  part  putrefies  with  confiderable  quicknefs,  and 
affords  much  ammoniack. 

The  alkalis  do  not  diffolve  it,  but  acids  combine  with  it. 
The  nitrick  acid  difengages  much  nitrogene,  and  afterwards 
diffolves  it  with  effervefcence,  and  difeii^agement  of  nitrous  gas. 
The  refidue  affords  oxalick  acid,  and  a  fmall  quantity  of  the 
malick  acid. 

This  fibrous  fubftance  is  of  the  nature  of  the  mufcular  fibre, 
which  caufed  Bordeu  to  call  the  blood  fluid  flefh  j  and  Jong  be- 
fore the  time  of  this  Celebrated  phyfician,  Paul  Zacchia  afferted 
that"  c^ro  nihil  aliud  eft  quam  fanguis  concretus."  (Quefl.  Lc- 


554  Properties  of  Fat, 

galis,  p.  239  )  This  fibrous  matter  is  more  animalized  than  the 
lymph  ;  and  it  appears  to  be  prepared  by  the  very  ac i  of  GircU'» 
lation  to  concur  in  augmenting  the  parts  of  the  human  body. 

Blood  contains  much  iron.  The  experiments  of  Mci^gbini, 
Bocquet,  and  Lorry,  prove  that  this  metal  is  capable  cA  ^aiiin^ 
into  the  blood  by  the  firit  palTagcs,  fince  patients  who  are  Uidor 
a  courfe  of  martial  medicine  void  it  by  the  way  of  urine.  \Vhrjii 
the  coagulated  part  of  the  blood  has  been  waftied,  if  that  r-^t 
which  has  retained  the  colouring  matter  be  burned,  andthc^  u^al 
lixiviated,  the  refidue  of  this  lixivium  is  in  the  ftate  of  faiiTon  of 
mars,  of  a  fine  colour,  and  ufually  obedient  to  the  magnet. 

The  colour  of  the  blood  has  been  attributed  to  iron  ;  and  it 
is  very  true  that  the  colour  appears  to  be  entirely  formed  of  it, 
for  there  exifts  no  veftige  of  this  metal  in  the  wafhed  and  dif- 
coloured  coagulum  :  but  as,  on  the  other  hand,  the  blood  does 
not  become  coloured  without  the  concourfe  of  air,  and  as  oxi- 
gene  alone  is  abforbed  in  refpiration,  it  appears  that  the  colour 
is;  owing  to  iron  calcined  by  the  pure  air,  and  reduced  to  the 
itate  of  red  oxide. 

From  this  manner  of  conceiving  the  phenomenon,  we  may 
perceive  why  animal  fubftances  are  fo  advantageous  in  afhfting 
and  facilitating  the  red  die,  and  why  thefe  fubilances  take  col- 
oars  more  ealUv. 


CHAPTER    IV. 

Concerning  Fat. 

FAT  is  a  condinfed  hiRammable  juice  contained  in  the  cel- 
lular membrane  :  its  colour  is  ufually  white,  but  fometimes  yel- 
low ;  its  tafte  infipid  ;  and  its  confiftence  more  or  lefs  firm 
in  the' various  fpecies  of  animals.  In  cetaceous  and  other  fift), 
it  is  nearly  fluid  ;  in  carnivorous  animals  the  fat  is  more  fluid 
than  in  frugivorous  animals,  according  to  Mr.  De  Fourcroy.  In 
the  fame  animal  it  is  mor$;  folid  near  the  kidneys,  and  under  the 
Ikin,  than  in  the  vicinity  of  the  moveable  vifcera  ;  as  the  animal 
vrrows  old,  the  fat  becomes  yellow,  and  more  folid.  Confult 
I>e  Fourcroy.  To  obtain  fat  in  a  ftate  of  purity,  it  is  cut  into 
fmall  pieces  -,  the  membranes  and  fmaller  veflels  are  feparated  ; 
it  is  wafhed,  then  fufed  with  a  fmall  quantity  of  water,  and  kept 
in  fufion  until  all  the  water  is  evaporated.  This  laft  fluid  which 
floats  above  it,  boils  ;  and  when  the  ebullition  ceafes,  it  is  a 
proof  that  all  the  water  is  diffipated. 

Fat  has  the  greateft  analogy  with  oils.  Like  them  it  is  not 
mifeible  with  water  ;  it  forms  foaps  with  alkalis  ;  and  burns  in 


Acid  of  Fat.  5  5  j; 

the  open  air,  by  the  contaft  of  an  ignited  fubftance,  at  a  fuffi- 
cient  heat. 

Neumann  treated  the  fat  of  the  goofe,  of  the  hog,  of  the  fiieep 
and  of  the  ox,  in  a  glafs  retort  by  a  graduated  fire.  He  obtain- 
ed phlegm,  an  empyreumatick  and  browniili  oil,  and  a  brilliant 
coal.  He  concludes  from  his  analyfis  that  there  is  little  differ- 
ence between  fats ;  and  that  of  the  ox  appears  only  to  contain 
a  little  more  earthy  matter.  This  very  imperfect  analyfis  throws 
no  light  on  the  nature  of  fat ;  and  we  are  indebted  to  Meflrs. 
Segner  and  Crell  for  experiments  of  a  much  more  interefting 
kind.     We  fhall  relate  the  chief. 

I.  Beef  fuet  diftilled  on  the  water-bath,  in  a  glafs  retort,  af- 
fords oil  and  phlegm  ;  it  forms  foaps  with  potalh  :  the  reddifh 
phlegm  has  an  acid  tafte  ;  efFervefces  with  alkali  without  red- 
dening the  fyrup  of  violets,  which  aiTumes  a  brown  colour  by 
this  mixture. 

2.  The  marrow  of  beef  affords  the  fame  produ6ls,  excepting 
that  a  fubftance  firft  pafles  over  of  the  confiftence  of  butter. 
The  phlegm  has  no  fmell  when  cold.  Fixed  alkali  occafions  a 
weak  effervefcence. 

Mr.  Crell  has  inftru£led  us  in  the  means  of  obtaining  a  pecul- 
iar acid  from  fat,  which  is  at  prefent  diilinguifhed  by  the  name 
of  the  Sebacick  Acid. 

He  at  firft  attempted  to  concentrate  this  acid  by  diftilling  off 
the  phlegm  ;  but  this  did  not  fucceed,  for  the  liquid  in  the  re- 
ceiver was  as  acid  as  that  in  the  retort.  He  then  faturated  all 
the  acid  with  potafh,  and  obtained  a  brownifh  fait  by  evapora- 
tion, which  he  fufed  in  a  crucible,  to  burn  the  oil  which  con- 
taminated it.  This  fait  by  folution  and  evaporation,  afforded  a 
foliated  fait.  He  poured  four  ounces  of  fulphurick  acid  upon 
ten  ounces  of  the  fait,  and  diftilled  by  a  very  gentle  fire.  The 
febacick  acid  pafTed  over  in  the  form  of  a  greyifh  vapour  ;  and 
half  an  ounce,  very  fuming  and  acrid,  was  found  in  the  re- 
ceiver. Crell  obferves  that,  in  order  to  fucceed  in  this  oper- 
ation, the  fait  muft  be  kept  a  long  time  in  fufion,  without  which 
the  acid  would  be  mixed  with  oil,  which  weakens  its  virtue. 

By  diftillation  of  fat  in  a  copper  alembick,  Mr.  Crell  obtained 
the  pure  acid.  But  the  fire  neceffary  for  this  purpofc  alters  the 
veflel,  caufes  the  tin  to  run  off,  and  the  acid  itfelf  becomes 
charged  with  copper. 

It  has  long  been  known  that  the  alkalis  form  a  kind  of  foap 
with  animal  fat.  Mr.  Crell,  by  treating  this  foap  with  a  folution 
of  alum,  feparated  the  oil,  and  obtained  the  febate  of  potafli  by 
evaporation  :  the  fulphurick  acid  afterwards  diftilled  from  this 
fait,  decompofes  it  j  and  by  this  means  the  febacick  acid  is  fea- 
aratcd. 


55<5  Properties  of  the  Add  of  Fat. 

Mr.  De  Morveau  melted  fuet  in  an  iron  pot ;  and  to  this  he 
added  pulverized  quicklime,  taking  care  to  ftir  it  continually  at 
the  commencement ;  at  the  end  of  the  operation,  a  confiderable 
heat  was  applied,  taking  care  to  raife  the  velTeh,  in  order  to  avoi4 
expofure  to  the  vapours.  When  the  whole  was  cold,  it  was 
found  that  the  fuet  had  no  longer  the  fame  folidity.  This  was 
boiled  in  a  large  quantity  of  water  ;  and  the  lixivium,  after  fil- 
tration, aflForded  a  brown  acrid  fait,  which  is  the  febate  of  lime. 

This  fait  is  foluble  in  water  but  would  require  too  much  time 
to  purify  it  by  repeated  cryftallizations.  This  purpofe  is  more 
eafily  anfwered  by  expoling  it  to  a  degree  of  heat  capable  cf 
burning  the  oil ;  after  which,  a  (ingle  folution  is  fufficient  to 
purify  it.  It  leaves  its  oil  upon  the  filtre  in  the  ftate  of  coal ; 
and  nothing  more  is  then  neceilary  than  to  evaporate  it. 

The  folution  ufually  contains  a  fmall  quantity  of  quicklime, 
which  may  be  precipitated  by  the  carbonick  acid.  This  fait 
treated  in  the  fame  manner  as  the  febate  of  potaih,  affords  the 
febacick  acid. 

This  acid  exifts  ready  formed  in  fuet  :  two  pounds  afforded 
fomewhat  more  than  feyen  ounces  to  Crell.  It  exilts  ready 
formed  in  the  fat,  fmce  earths  and  alkalis  difengage  it. 

It  has  the  greateft  affinity  with  the  muriatick  acid,  as  it  forms 
with  potafh  a  fait  which  melts  in  the  fire  without  being  decom- 
pofed  *,  it  atts  powerfully  on  gold,  when  mixed  with  the  nitrick^ 
acid  ;  it  precipitates  filver  from  the  nitrate  of  filver  ;  it  forms  9 
fublimate  with  mercury,  and  the  folution  of  this  fublirnate  is  not 
rendered  turbid  by  the  muriate  of  foda.  But  though  this  acid 
approaches  the  muriate  in  feveral  refpecls,  it  differs  from  it  in 
-Others,  and  hitherto  feems  to  be  nothing  but  a  modification  of 
that  acid.  With  foda,  it  forms  cryftals  in  needles,  and  a  cryf- 
taHized  fait  with  lime.     It  decompofes  common  fait,  &c. 

Mr.  Crell  obtained  the  acid  of  fat  by  diflillation  from  the  but- 
ter of  cacao.     Spermaceti  likewife  affords  it. 

The  properties  of  this  acid  are  the  following  : 

It  reddens  blue  vegetable  colours. 

It  affumes  a  yellow  colour  by  fire,  and  leaves  a  refidue,  which 
announces  a  partial  decompofition.  From  this  circumftance, 
Mr.  Crell  confiders  it  as  occupying  the  middle  fpace  between 
the  vegetable  acids  which  are  deftroyed  by  fire,  and  the  mineral 
which  receives  no  alteration.  Its  exifience  in  the  butter  of  ca- 
cao, and  in  fats,  is  favourable  to  the  notions  of  Crell  on  this  fub- 

jea. 

,  It  attacks  the  carbonates  of  lime  and  alkali  with  effervefcenc^ 
and  with  them  for  the  falts  which  Bergmann  finds    re    be  vti  , 
fimilar  to  the  acetites  with  the  fame  bain   . 


Add  of  Fat,     Bih,  ^07 

This  3qid,  as  Mr.  De  Morveau  obferves,  feems  to  have  fome 
}j(£i:ion  upon  glafs.  Mr.  Crell  having  digefted  it  feveral  times 
upon  gold,  always  obtained  a  precipitate  of  white  earth,  which 
was  not  lime,  but  which  he  prefumes  to  have  been  carried  up  in 
the  diftillation,  and  could  only  arife  from  the  retort  itfelf. 

This  acid  does  not  perceptibly  a£l  on  gold  :  but  it  attacks  the 
oxide,  and  forms  a  cryftallizable  fait,  as  it  does  likewifp  with 
the  precipitates  of  platina. 

It  unites  with  mercury  and  with  filver  ;  yielding  the  latter 
to  the  muriatick  acid,  but  not  the  former  :  It  takes  both  from 
the  fulphurick  acid,  lead  from  the  nitrick  and  acetous  acid,  and 
tin  from  the  nitro-muriatick  acid. 

It  attacks  neither  bifmuth,  cobalt,  nor  nickel. 

It  does  not  decompofe  the  fulphates  of  copper,  of  iron,  or  of 
zinc  ;  nor  the  nitrates  of  arfenick,  manganefe,  zinc,  &c. 

It  reduces  the  oxide  of  arfenick  by  diftillation.  Crell  formed 
a  febacick  ether. 

From  this  analyfis  it  appears  that  fat  Is  a  kind  of  oil  or  but- 
ter rendered  concrete  by  an  acid. 

Its  ufes  are— I.  To  keep  up  the  heat  pf  the  tjody,  and  de- 
fend the  yifcera  from  the  impreffion  of  external  cold.  2.  To 
ierve  as  nourilhment  or  fupport  for  the  animal  on  the  occafions 
pf  want,  ficknefs,  &c. 


CHAPTER  V. 

Concerning  the  Bile, 

THE  Bile  is  one  of  thofe  humours  which  it  is  eflential  to 
know,  on  account  of  the  influence  and  efFe6l  it  has  both  in  the 
ftate  of  health  and  diforder.  We  fhall  even  fee  that  its  analy- 
fis is  fufficiently  perfe£l  to  afford  ii^ftru6lion  in  an  affinity  of 
cafes. 

This  humour  is  feparated  in  a  large  vifcqsof  the  lower  belly, 
called  the  Liver  ;  it  is  afterwards  depofued  in  a  bladder,  or  re- 
fervoir,  called  the  Gall  Bladder  ;  from  which  it  is  conveyed  in- 
to the  duodenum  by  a  particular  channel. 

The  bile  is  glutinous,  or  imperfectly  fluid,  like  oil ;  of  a  very 
bitter  tafte  ;  a  green  colour,  inclining  to  yellow  \  and  froths 
by  agitation  like  the  folution  of  foap. 

If  it  be  diftilled  on  the  water  bath  it  aflx)rds  a  phlegm,  whicii 
is  neither  acid  nor  alkaline,  but  putrefies.  This  phlegm,  acord- 
iiig  to  the  obfervation  of  Mr.  De  Fourcroy,  often  emits  a  fmell 
refembling  that  of  mu{k  ;  \yX^  Itfelf  has  the   fame  property,  ac- 


^^S  Dijfilation  and 

cording  to  the  general  obfervation  of  butchers.  When  the  bile 
has  given  out  all  the  water  it  is  capable  of  affording  upon  the 
water  bath,  the  refidue  is  a  dry  extract,  which  attracts  the  hu- 
midity of  the  air,  is  tenacious,  pitchy,  and  foluble  in  water. 
By  diftillation  in  a  retort,  it  affords  ammoniack,  an  empyreu- 
matick  animal  oil,  concrete  alkali,  and  inflammable  air.  The 
coal  is  more  eafily  incinerated  than  that  we  have  laft  treated  of. 
It  contains  iron,  carbonate  of  foda,  and  phofphate  of  lime. 

All  the  acids  decompofe  bile  ;  and  difengage  an  oily  fubftance 
which  rifes  to  the  top.  The  falts  afterwards  obtained  bv  evap- 
oration, have  foda  for  their  bafis  ;  which  {hows  that  the  bile  is 
a  true  animal  foap.  The  oil  which  is  combined  with  foda  is  a- 
nalogous  to  refins,  is  foluble  in  fpirit  of  wine,  &c. 

The  metallick  folutions  decompofe  bile  by  double  affinity, 
and  produce  metallick  foap. 

Bile  unites  with  oils,  and  cleans  (luffs  in  the  fame  manner  as 
foap. 

Bile  is  foluble  in  alcohol,  which  feparates  the  albuminous 
principle.  It  is  this  laft  fubftance  which  renders  bile  coagulate 
by  fire  and  by  acids  j  and  it  is  this  likewife  which  haftens  its  pu- 
trefadlion. 

The  conftituent  principles  of  bile  are,  water,  a  fpiritus  re6lorj 
a  lymphatick  fubftance,  a  rcfinous  oil,  and  foda.  Mr.  Cadet 
has  found  a  fait  in  it,  which  he  thought  firailar  to  fugar  of  milk  ; 
this  fait  is  probably  no  other  than  that  which  was  difcovered 
by  Mr.  Poulletier. 

Bile  is  therefore  a  foap,  refulting  from  the  combination  of  fo- 
da with  a  matter  of  the  nature  of  refins,  and  a  lymphatick  fub- 
ftance, which  renders  it  fufceptible  of  putrefaction  and  coagula- 
tion. This  fubftance  gives  the  bile  the  character  of  animaliza- 
tion,  diminifties  its  acridity,  and  favours  its  mixture  with  the 
other  humours.  The  faline  part  renders  the  bile  more  fluid  and 
foluble  in  water  5  and  it  is  more  acrid  the  more  this  principle 
abounds. 

The  refinous  part  differs  from  vegetable  refins— i.  Becaufe 
thefe  do  not  form  foap  with  fixed  alkalis.  2.  Becaufe  they  are 
more  acrid  and  more  inflammable.  3.  Becaule  the  animal  re- 
fin  melts  at  the  temperature  of  40  degrees,  and  acquires  a  fluid- 
ity fimilar  to  that  of  fat ;  from  which  however  it  differs  in  not 
being  foluble  in  alcohol,  in  which  refpcO  it  approaches  to  fper- 
maceti. 

The  acids  which  a£l  upon  bile  in  the  firft  paffages,  decom- 
pofe it.  The  greenirh  yellow  colour  of  the  excrements  of  in- 
fants at  the  breaft,  arifes  from  a  fimilar  decompofition  ;  and  it 
is  the  refinous  part  which  tinges  them.      From  the  adlion  ef 


Habitudes  of  the  Bile,  5^<j 

the  bile  upon  acids,  we  may  deduce  the  efFcdl  of  thefe  remedies 
when  the  evacuations  are  putrid,  and  the  degeneration  of  the 
bile  is  feptick.  The  lymph  is  then  coagulated,  and  the  excre- 
ments become  harder.  This  (hews  the  reafon  why  the  excre- 
ments of  infants  are  fo  frequently  clotted. 

When  the  bile  remains  a  long  time  in  the  firft  paffages,  as 
for  example  in  chronical  difordcrs,  it  afTumes  a  black  colour, 
becomes  thick,  acquires  the  confidence  of  an  unguent,  and  forms 
a  liming  of  feveral  lines  in  thicknefs  in  the  inteftinal  canal,  ac- 
cording to  the  obfervation  of  Mr.  De  Fourcroy.  When  fmear- 
cd  on  paper,  and  dried,  it  becomes  green  ;  diluted  with  water, 
it  forms  a  tin£ture  of  a  yellow  green  colour,  from  which  a  large 
quantity  of  black  fcales  are  precipitated  :  with  alcohol  it  like- 
wife  forms  a  bhck  tindure,  and  depofites  that  laminated  brilliant 
fait-  difcovered  in  biliary  calculi  by  Mr.  Poulleticr  de  la  falle. 
This  humour,  which  forms  the  atra  bills  of  the  ancients,  is 
nothing  but  the  bile  rendered  thick  ;  and  in  this  cafe  the  efFe6b 
of  acids,  and  the  danger  of  irritating  fubftances,  may  be  eafily 
accounted  for.  This  thickening  of  the  bile  clogs  the  vifcera  of 
the  lower  belly,  and  produces  obftru6tions. 
.  Many  diforders  are  referable  to  the  predominant  character 
of  the  bile.  On  this  fubjedt,  the  interelting  Memoirs  of  Mr. 
De  Fourcroy  may  be  consulted,  in  the  collection  of  the  Royal 
Society  of  Medicine  for  the  years  1782  and  1783. 

When  the  bile  becomes  thick  in  the  gall  bladder,  it  forms  th© 
concretions  called  biliary  calculi.  Mr.  PouUetier  has  paid  great 
attention  to  the  analyfis  of  thefe  (tones.  He  has  obferved  that 
they  are  foluble  in  ardent  fpirit.  When  the  folution  is  left  to 
itfeif  for  a  certain  time,  brilliant  and  light  particles  are  feen  in 
it,  which  Mr.  Poullstier  found  only  in  the  human  calculi,  and 
which  appeared  to  him  to  have  the  greateft  analogy  with  the  fait 
of  benzoin. 

Mr.  De  Fourcroy  has  obferved  that  the  difcovery  of  Mr.  Dc 
la  Salle  has  been  confirmed  by  the  Royal  Society  (of  Medicine,) 
which  has  received  feveral  biliary  calculi  that  appeared  to  be 
formed  by  a  fait  analagous  to  that  which  was  obferved  by  this 
chemill.  They  confift  of  mafles  of  tranfparent  cryftalline  plates, 
fimilar  to  mica  or  talc.  The  fociety  of  Medicine  poflefles  in  its 
collection  a  gall  bladder  entirely  filled  with  this  faline  concre- 
tion. 

We  may  therefore,  as  De  Fourcroy  obferves,  admit  of  two 
kinds  of  calculi ;  the  one  are  opaque,  and  are  afforded  only  by 
the  condenfed  bile  •,  the  others  confift  of  the  cryftals  we  have  de- 
fcribed. 


J^O  Paris  of  Animals* 

Boerhaavc  obferved,  long  fince,  that  the  gall  bladder  of  oxen^ 
at  thd  end  of  the  winter,  was  filled  with  calculi,  but  that  the 
frefh  pafturage  diffipated  thefe  concretions. 

Soaps  have  been  propofed  as  folvents  for  thefe  calculi.  The 
academy  of  Dijon  has  publiftied  the  fucccfs  of  a  mixture  of  ef< 
fence  of  turpentine  and  ether.  Frefli  vegetables,  which  arc 
fuch  fovereign  remedies  in  defi:roying  thefe  concretions,  owe 
their  virtue  perhaps  to  the  circumftance  that  they  develope  an 
acid  in  the  ftomach,  as  we  have  obferved  in  treating  of  the  gaf- 
trick  juice. 

The  ufe  of  the  bile,  in  the  animal  economy,  confifts,  no  doubt, 
in  dividing  thofe  fubftances  which  have  undergone  a  firft  digef- 
tion  in  the  flomaeh  ;  and  giving  an  efficacy  and  force  to  the 
motion  of  the  inteftines.  When  its  flux  is  interrupted,  it  a- 
bounds  in  the  blood,  and  the  whole  body  becomes  of  a  yellow 
tinge. 

The  bile  or  gall  is  an  excellent  vulnerary  externally  applied  ". 
internally  taken,  it  is  a  good  ftomachick,  and  one  of  the  bed 
deobftruents  the  art  of  medicine  pofleiTes.  This  kind  of  reme- 
dies deferves  the  preference,  as  being  more  analogous  to  the 
conftitution  ;  and  bile  is  a  proper  medicine  when  the  digeftion'' 
languifties,  or  the  vifcera  of  the  lower  belly  are  clogged. 

Bile,  like  other  foaps,  removes  fpots  of  oil,  or  other  greafy 
matter,  from  fubftances  to  which  they  are  adherent. 


CHAPTER  VI. 

Concerning  the  Soft  and  White  Parts  of  Animals. 

THESE  parts  are  perhaps  lefs  known  than  thofe  of  which 
we  have  juit  treated  ;  but  their  analyfis  is  not  lefs  interefting  s 
we  may  even  affirm  that  is  more  fo  ;  becaufe  the  application  of 
the  knowledge  we  may  acquire  on  this  fubje6l,  will  daily  pre^ 
fent  itfelf  in  the  commoncft  purpofes  of  domeftick  life. 

All  the  parts  of  animals,  whether  membranes,  tendons, 
aponeiirofes,  cartilages,  ligaments,  or  even  the  flcin  and  horns, 
contain  a  mucous  fubfiance  very  foluble  in  water,  but  not  in 
alcohol,  and  known  by  the  name  of  Jelly.  Nothing  need  be 
done  to  obtain  it,  but  to  boil  thefe  animal  fubftances  in  water, 
and  concentrate  the  decodlion^  until  by  mere  cooling  it  alTumes 
the  form  of  a  folid  tremulous  mafs. 

Jellies  are  very  common  in  our  kitchens  :  and  the  cooks  are 
perfeftly  well  acquainted  with  the  methods  of  making  them, 
and  of  giving  them  foiidity  when  the  temperature  of  the  atmof- 


Properties  if  Jellies.     PertabU  Soups •  ^6 1 

phere  is  very  hot.  This  jelly  of  harts-horn  is  extraf^ed  by  a 
funilar  operation,  and  afterwards  rendered  white  with  the  milk 
of  almonds.  This  kind  of  food,  duly  fcented,  is  ferved  up  at 
our  tables  by  the  name  of  hlanc  manger.  Jellies  are  in  general 
reilorative  and  nourifhing  :  that  of  harts-horn  is  aftringent  and 
emollient. 

Jellies  in  general  have  no  fmell  iti  their  natural  ftate,  and 
their  talle  is  infipid.  By  diltillation  they  afford  an  infipid  and 
inodorous  phlegm,  which  eafily  putrefies.  A  itronger  heat  cau- 
fes  them  to  fsvell  up,  become  black  and  emit  a  fetid  odour  ac- 
companied with  white  acrid  fumes.  An  alkaline  phlegm  then 
pafTes  over,  fucceeded  by  an  empyreumatick  oil,  and  a  httle  car- 
bonate of  ammoniack.  A  fpongy  coal  remains  which  is  with 
clifEcuhy  reduced  to  afhes,  and  affords  by  analyfis  muriate  .of 
foda  and  phofphate  of  lime. 

Jelly  cannot  be  kept  above  a  day  in  the  fummer,  or  two  or 
three  in  the  winter.  When  it  becomes  fpoiled,  white  livid 
fpets  are  formed  on  Its  furface,  which  fpeedily  extend  to  the 
bottom  of  the  pots.  A  large  quantity  of  nitrogenous,  hydro- 
genous, and  carbonick  gas  is  emitted. 

Water  diiTolves  jellies  perfedlly.  Hot  water  dlfToIves  a  large 
quantity,  as  they  become  confident  only  by  cooling.  Acids 
Ukewife  difiblve  them,  and  alkalis  more  efpccially  do. 

The  nitrick  acid  difengages  nitrogene  gas,  according  to  the 
fine  experiments  of  M.  Berthollet. 

When  jelly  has  been  extradled  without  long  decoction,  and 
has  no  lymph  mixed  with  it,  it  then  pofTefTes  moft  of  the  char- 
adlers  of  the  vegetable  jelly  :  but  it  is  feldom  obtained  without 
a  mixture  of  lymph  ;  and  in  this  cafe  it  efTentially  differs  from 
the  vegetable  jellies,  in  affording  nitrogene  gas  and  ammoniack. 

If  jelly  be  concentrated  to  fuch  a  degree  as  to  give  it  the  form 
of  a  cake,  it  is  deprived  of  the  property  of  putrefying;  and  by' 
this  means  the  dry  or  portable  faups  are  formed.      The  follow- 
ing is  a  receipt  for  preparing  thefe  cakes  : 
Calves  feet  4 

Leg  of  beef  1 2  pounds. 

Knuckle  of  veal  4  pounds. 

Leg  of  mutton  10  pounds. 

Thefe  are  to  be  boiled  in  a  fufEcient  quantity  of  water,  and 
the  fcum  taken  off  as  ufual ;  after  which  the  foup  is  to  be  fep- 
arated  from  the  meat  by  ftraining  and  prelTure.  The  meat  is 
then  to  be  boiled  a  fecond  time  in  other  water  ;  and  the  two 
decodions,  being  added  together,  muft  be  left  to  cool,  in  order 
that  the  fat  may  be  exa^^ly  leparated.  The  foup  mud  then  be 
clarified  with  five  or  fix  whites  of  eggs,  and  a  fuificient  quantity 
3...Z 


5^2  JeUles.     Glues. 

of  common  fait  added.  The  liquor  is  then  ftrained  tlirough 
flannel,  and  evaporated  on  the  water-bath  to  the  confidence  of 
a  very  thick  palie  ;  after  which  it  is  fpread  rather  thin  upon  a 
fmooth  fbone,  then  cut  into  cakes,  and  laftly  dried  in  a  Itove  un- 
til it  becomes  brittle  :  thefe  cakes  are  kept  in  well  clofed  bottles. 
The  fame  procefs  may  be  ufed  to  make  a  portable  foup  of  the 
flelii  of  poultry  ;  and  aromatick  herbs  may  be  ufed  as  a  feafon- 
ing,  if  thou:{ht  proper. 

Thefe  tab'ers  or  cakes  may  be  kept  four  or  five  years.  When 
intended  to  he  ufed,  the  quantity  of  half  an  ounce  is  put  into  a 
large  glafs  of  boilifi^  water,  which  is  to  be  covered,  and  fet  upon 
hot  afhes  for  a  quarter  of  an  hour,  or  until  the  whole  is  entirely 
diflblved.  In  forms  an  excellent  foup,  and  requires  no  addition 
but  a  fmall  quantity  of  fait. 

The  cakes  of  ho  ckiack,  which  are  prepared  in  China  and  are 
known  in  France  by  the  name  of  colle  de pen  cTdne^  are  made 
with  animal  fubftances.  They  are  ufed  in  diforders  of  the  lungs 
in  a  dofe  from  half  a  dram  to  two  drams. 

The  nature  of  the  fubflances  made  ufe  of,  and  the  method 
of  operating,  produce  fome  difference  in  thefe  produ6ls.  Old 
or  lean  animals  aflx^rd  in  general  better  glue  than  the  young  and 
fat.  For  a  full  account  of  the  art  of  making  glue,  confult  U Art 
de  faire  differ entes  Efpeces  de  Colle^  par  M,  Duhamel  de  Monceau^ 
de  r Academie  des  Sciences. 

1.  To  make  the  (Irong  or  EngHOi  gltte,  the  parings  of  leath- 
er, the  flcins  of  animals,  with  the  ears  of  oxen,  calves,  fheep,  &c 
are  ufed.  Thefe  matters  are  firfl  digefted  in  water,  to  pene- 
trate the  texture  of  the  (kins  \  they  are  afterwards  fteeped  in 
lime  water,  taking  care  to  ifir  and  agitate  them  from  time  to 
time;  they  are  tiien  laid  in  a  heap  for  fome  time,  afterwards 
wailied,  and  the  fuperabundant  water  preifed  out  by  a  prcfs. 
Thefe  Ikins  are  then  digeiled  in  water  gradually  heated  to  ebul- 
lition. The  liquor  is  afterwards  poured  out,  and  feparated  with 
preHlire.  Lalliy,  it  is  thickened  by  evaporation  of  the  water 
by  heat,  and  poured  on  flat  polilhed  ftones  or  into  moulds,  and 
left  to  dry  and  harden. 

This  glue  is  brittle.  It  is  foftened  by  heating  it  with  a  fmall 
qunn^iiy  of  water  for  ufe,  and  is  applied  with  a  brufli.  Car- 
penters and  cabinet  makers  ufe  it  to  iaften  pieces  of  wood  to- 
gether. 

2.  The  glue  of  Flanders  is  merely  a  diminutive  of  the  ftrong 
glue.  It  has  not  the  fame  confidence,  and  cannot  be  ufed  in  glu- 
ing wood  \  it  is  thinner  and  more  tranfparent  than  the  former.  It 
is  made  with  a  more  accurate  choice  of  materials,  and  with 
greater  care.     It  is  ufed  by  defigners.     Mouth  glue  is  made  of 


Jelly.    Glue.     Ifwglafi.  563 

this,  to  ftitch  paper  together,  by  fuflng  it  again  with  the  addi- 
tion of  a  fmall  quantity  of  water,  and  four  ounces  of  fugar  candy 
to  a  pound  of  the  glue. 

3.  The  colle  de  gand  is  made  with  the  cHppings  of  white 
gloves,  well  fteeped  in  winter,  and  boiled  :  it  is  likewife  made 
with  the  clippint^s  of  parchment.  In  order  that  thefe  two  kinds 
of  glue  maybe  fit  for  ufe,  it  is  neceiTary  that  they  be  of  the 
confidence  of  a  tremulous  jelly  when  cold/* 

4.  Fifli  glue,  orifinglafs,  is  made  of  the  mucilaginous  parts 
of  a  large  fifli  commonly  found  in  the  RufTian  feas.  The  ilcin, 
the  fins,  and  the  nervoub  part,  are  cut  into  dices,  boiled  on  a  flow 
fire  to  the  confiftence  of  a  jelly,  fpread  out  to  the  thicknefs  of 
a  (heet  of  paper,  and  formed  into  cakes  or  lorig  pieces,  fuch  as 
\ye  receive  them  from  Holland.  The  filk  manufaifiurers,  anid 
more  efpecially  the  ribbon  weavers,  ufe  it  to  give  a  luftre  to 
their  goods  ;  it  is  alfo  ufed  to  ftifFen  gauzes,  and  to  clarify  or 
fine  wine,  by  mixing  a  folution  of  this  fubftance  with  it.  Ifin- 
glafs  enters  into  the  compofition  of  fome  platters.  It;  is  excej- 
lent  to  correal  acrid  humours,  and  terminate  obflinate  venereal 
diforders. 

Gilders  fize  is  made  by  boiling  eel  fkins  in  water  with  a  fmaU' 
quantity  of  lime  \  the  water  is  (trained  off,  and  fome  whiles  of. 
eggs  added.  When  it  is  intended  to  be  ufed,  it  is  heated,  ap- 
plied to  the  furface  intended  to  be  gilded,  and  wJiea  ^,is  ^ry 
the  gold  leaf  is  laid  on. 

5.  The  glue  of  fnails  is  made  by  expofing  fnails  to  the  futij 
and  receiving  in  a  glafs  the  fluid  which  flows  from  them.  This 
liquor  is  mixed  with  tlie  juice  of  milk  thiflle.  It  is  ufed  to  ce- 
ment glafles  together,  which  are  afterwards  expofed  to  the  fun 
to  dry. 

6.  To  make  the  glue  of  parchment,  or  parchment  ^ze,  (^o 
or  three  pounds  of  the  clip-^ings  of  parchment  are  put  into  a  pail 
of  water.  Tliefc  are  boiled  until  half  the  water  is  evaporated 
after  which  tlie  whole  is  ftrained  through  a  cloth,  and  left  to 
fettle. 

The  glue  or  fiz^ufed  in  the  paper  maiuifadories,  to  fortify 
the  paper,  and  to  repair  its  defe<^ls,  is  made  with  wheat  flour  dif- 
fufed  in  boiling  water,  and  flrained  throuj^h  a  fieve.  This  fizQ 
muft  be  ufed  the  following  day,  and  neither  fooner  nor  later. 
The  paper  is  afterwards  beat  with  a  mallet,  fiz«;d  a  fecond  time, 
put  imo  the  prefs,  to  fmooth  and  unite  it,  and  afterwards  tended 
by  hammering. 

•  Thefe  weaker  gUies  are  called  Size  by  our  work,nien,  who  apply  die 
oame  ot  Giae  to  the  ftroog  glue  only. 


$64  Mufcular  Parts, 


CHAPTER  VII. 

Concerning  the  Mufcular  or  Flefhy  Parts. 

THE  mufcles  of  animals  are  formed  of  longitudinal  fibres 
connefled  together  by  the  cellular  membrane,  and  impregnated 
with  various  humours,  in  which  we  find  partly  thofe  we  have 
already  examined  feparately. 

The  analyfis  of  thefe  fubftances  by  diftillation  afforded  us  lit- 
tle inftrudion  refpeding  their  nature.  The  produds  were,  wa- 
ter which  cafily  became  putrid,  alkaline  phlegm,  empyreumat- 
ick  oil,  carbonate  of  ammoniack,  and  a  coal  which  afforded  by 
incineration  a  fmall  quantity  of  fixed  alkali,    and  febrifuge  fait. 

The  procefs  which  fucceeds  the  belt  for  feparately  obtaining 
the  various  fubftances  which  compofe  mufcles,  is  the  following 
which  has  been  pointed  out  to  us  by  Mr.  De  Fourcroy. 

1.  The  mufclc  is  firft  wafhed  in  cold  water  :  by  this  means 
the  colouring  lymph,  and  a  faline  fubflance,  are  taken  up.  By 
flow  evaporation  of  this  water,  the  lymph  coagulates,  and  may 
be  feparated  by  the  filtre  ;  and  a  continuance  of  the  evaporation 
affords  the  faline  matter. 

2.  The  refidue  of  the  firft  wafhing  is  digefted  in  alcohol, 
which  difiblves  the  extractive  matter,  and  a  portion  of  the  fait ; 
the  extradl  is  feparated  by  the  evaporation  of  the  alcohol. 

3.  The  refidue  of  the  firft  operations  is  to  be  boiled  in  water, 
which  takes  up  the  jelly,  the  fat  part,  and  the  remaining  faline 
and  extractive  matter.  The  fat  oil  fwims  on  the  furface 
and  may  be  taken  off. 

4.  After  thefe  operations,  there  remains  only  a  white  infipi4 
fibrous  fubftance,  infoiuble  in  water  ;  which  contrafts  by  heat, 
like  other  animal  fubftances  ;  affords  ammoniack,  and  very  fetid 
oil,  by  diftillation.  Nitrogene  gas  is  obtained  from  it  by  the 
ziitrick  acid.  It  poffeffes  all  the  characters  of  the  fibrous  part  of 
the  blood  in  which  fluid  it  is  armed,  to  be  afterwards  depofited 
in  the  mufcles,  where  it  receives  the  laft  character  appropriated 
to  it. 

Mr.  Thouvenel,  to  whom  we  are  indebted  for  interefting  re- 
fearches  on  this  fubject,  has  found  in  fleOi  a  mucous  extradive 
fubftance,  foluble  in  water  and  in  alcohol,  poffeffmg  a  peculiar 
tafte  which  jelly  has  not ;  and  when  this  fubftance  is  very  much 
concentrated,  it  affumes  an  acrid  and  a  bitter  tafte.  -Firedevel- 
opes  an  aromatick  flavour  in  it.  This  fubftance  evaporated  tq 
dryncfs,  affumes  a  bitter,   acrid,  and  faline  tafte.      It  fwells  up 


Jnalyfis  of  Flejb.  565 

upon  hot  coals,  and  liquefies ;  emitting  an  acid,  penetrating 
fmell,  refembling  that  of  burned  fugar.  It  attrads  the  humid- 
ity of  the  air,  and  forms  a  faiine  efFiorefcence.  In  a  hot  atraof- 
phere  it  becomes  four,  and  putrefies.  All  thefe  chara£lers  indi- 
cate a  refembiance  between  this  lubftance,  the  faponaceous 
cxtra£\s,  and  the  faccharine  matter  of  vegetables.  Mr.  Thou- 
venel,  who  has  Ukewife  analyfed  the  fait  obtained  by  the  decoc- 
tion and  flow  evaporation  of  flefli,  obtained  it  fometimes  in  form 
of  down,  and  fometimes  in  that  of  cryftals,  whofe  figure  he 
could  not  defcribe.  This  fait  appeared  to  him  to  be  a  phofphatc 
of  potalh  in  frugivorous  quadrupeds,  and  muriate  of  potafli  in 
carnivorous  reptiles.  It  is  probable,  as  Mr.  De  Fourcroy  ob- 
ferves,  that  this  fait  is  a  phofphate  of  foda  or  of  ammoniack, 
mixed  with  the  phofphate  of  lime.  Thefe  falts  are  indicated,  and 
even  with  excefs  of  acid,  like  thofe  of  urine,  by  lime-water 
and  ammoniack,  which  form  white  precipitates  in  the  decodion 
of  fleih. 

The  moft  abundant  part  of  mufcles,  and  that  "which  confti- 
tutes  their  predominating  character  is  the  fibrous  matter.  The 
characters  which  diftinguifh  this  fubftance  are — 

I.  It  is  not  foluble  in  water.  2.  It  affords  more  nitrogene 
gas  by  the  nitrick  acid  than  other  fubftances  do.  3.  It  after- 
wards affbrds  the  oxalick  acid,  and  the  malick  acid.  4.  It  pu- 
trefies eafily  when  moiilened,  and  affords  much  concrete  ammo- 
niack by  diftillation. 

The  other  three  fubflances  contained  in  flefh,  namely,  the 
lymph,  the  jelly,  and  the  fat  part,  are  the  fame  fubftances  con- 
cerning which  we  have  already  treated,  under  the  fame  denom- 
inations. 

From  thefe  principles  we  may  give  the  etiology  of  the  form- 
ation of  foup,  and  follow  the  fuccefiive  difengagements  of  all 
the  principles  we  have  fpoken  of. 

The  firlt  impreflion  of  the  fire,  v/hen  a  foup  is  made,  is  the 
difengagement  of  a  confiderable  fcurn,  which  is  taken  off  until 
it  no  longer  appears.  This  fcum  aiifes  merely  from  the  difen- 
gagement of  the  lymph,  which  coagulates  by  the  heat.  It  af- 
fumes,  by  the  imprefUon  of  the  fire>  a  red  colour,  which  it  does 
not  naturally  poflefs. 

At  the  fame  time  the  gelatinous  part  is  difengaged,  which  re- 
mains difiblved  in  the  foup,  and  congeals  only  by  cooling.  It 
forms  on  the  furface  of  cold  foup  a  body  more  or  lefs  thick, 
according  to  the  nature  of  the  fubft:ances,  and  the  age  of  the 
animals  ;  for  young  animals  afford  a  larger  quantity  than  fuch 
as  ar«  ol4< 


^66.  Ccncertjing   Urine. 

As  iopn  as  thq  flejli,  is  penetrated  by  heat,  flat  round  drops 
arifc,  and  float  a.t  the-rurface  of  tlie  fluid,  in  which  they  are  not 
afterwards  difiblvedj  but  congeal  by  cooling,  and  exhibit  all  the 
chara^lers  of  fat. 

In  proportion  as  the  digeftion  proceeds,  the  mucous  extr?.6l- 
ive  part  feparates  :  the  foup  becomes  coloured,  aflumes  its  pe- 
culiar odour  and  tafte  j  and  it  is  more  particularly  to'this  princi- 
ple that  its  properties  are  owing. 

The  fait  which  is  at  the  fame  time  diflblved  takes  ofl^the  in- 
(itpidity  of  all  the  before  mentioned  principles  :  and  at  this  pe- 
riod the  foup  is  coM.ipletely  made. 

According  to  the  nature  of  the  fevcral  principles  which  arc 
djfeng^ged,  and  the  order  in  which  they  appear,  it  is  evident 
that  the  management  of  the  fire  is  not  a  matter  of  indifference. 
if  the  ebullition  be  haflened,  and  a  proper  time  be  not  allowed 
for  the  difengagement  of  the  mucous  extracSlive  matter,  the 
three  inodorous  and  infipid  principles  are  obtained  j  and  this  is 
obferv.ed  in  foups  made  by  cooks  who  are  haltened,  or  have  not 
timp  allowed  to  pay  a  due  attention  to  their  work.  When  en 
the  contrary,  the  digedion  is  made  over  a  flow  fire,  the  princi- 
ples feparate  one  after  the  other,  in  order  ;  the  fkimming  is 
niore  accurately  performed  j  the  aromaiick  flavour  which  is  dif- 
engaged  combines  more  intimately,  and  the  foup  is  of  an  excel- 
lent flavour.  The  A?  are  the  foups  of  the  good  women  who  per- 
form better  with  a  fmall  quantity  of  meat,  than  profefled  cocks 
with  their  ufual  prodigality>  and  in  this  cafe-  we  may  fay  that 
the  form  is  of  more  value  than  the  fubftance. 

The  heat  muft  not  be  applied  too  long  ;  for  the  great  evap- 
oration, by  concentrating  the  principle  of  fmell  and  talle  at  the 
fame  time  witli  the  fait,  renders  them  acrid  and  bitter. 


CHAPTER     VIIJ. 

Concerning  Urine. 

URINE  is  an  excrementitious  humour  of  the  body  ;  and  it 
is  one  of  iht  fluids  of  which  it  is  of  the  grcateit  importance  to 
pOilefs  an  accurate  knowledge;  becaufe  the  pradical  phyficlan 
roay  derive  the  greate't  advantage  from  informarion  of  this  na- 
ture. It  is  known  to  what  a  degree  of  extravagance  the  n)ar- 
vellous  pretenfions  of  this  kind  have  been  carried.  The  de- 
lirium has  proceeded  to  fuch  a  heiglit,  as  even  to  pretend  to  af- 
certain  from  the  urine,  not  only  the  nature  of  the  diforder,  and 
the  character  of  the  patient,  but  like  wife  the  fex  and  condition. 


CharaBers  of  Urine,  c;^j 

Tiie  true  phyncian  has  never  given  inro  this  excefs  :  but  he 
has  al'.Vriys  clerivcd  afliilance^  in  his  practice,  from  the  charac- 
ters exhibited  by  the  urine  -,  and  ihis  is  the  humour  from  which 
he  may  draw  the  mod  latisfacSl  )ry  indications.  It  carries  out, 
as  we  may  fiy,  the  internal  characl:er  *,  and  a  phyhcian  who 
kno^vs  how  to  form  a  jud-^msnt  upon  its  properties  may  deduce 
the  rridfl  iniiru<5>ive  confequences  from  it.  Munro,  in  his 
Treatife  of  Comparative  Anatomy,  has  defcribed  the  organs 
"(vhich,  in  birds,  fupply  rhe  place  of  the  kidneys  :  they  are  placed 
hear  the  vertebral  column  ;  and  communicate,  by  two  duels,  to 
the  vicinity"  of  the  anus.  He  affirms  that  the  urine  of  birds  is 
t'hat  whitiih  fabftance  which  alrnoft  always  accompanies  the 
c:xremsnts. 

Chemical  analyfis  ought  to  enlighten  the  phyfician  in  his  re- 
fearches  concerning  the  Urine.  Fhe  nature  of  the  priiiciples 
it  carries  ofr  in  certain  circumflances,  affords  va(l  information 
refpe^ting  the  predominant  principle  in  the  fluids  of  the  human 
body.  Its  various  Itates  (hew  the  dlfpoRtion  of  the  conftitution. 
t^erfons  of  a  very  irritable  habit  have  th^'iiri^ne  of  a  lighter  col- 
our than  others;  gouty  perfons  evacuate  turbid  urine  ;  and  it 
has  been  obferved  that,  when  the  bones  become  fort,  the  urine 
carries  olF  the  phofphate  of  lime,  which  conltitutes  their  bafis  ; 
inflances  of  which  were  obferved  in  the  perfons  of  Mrs.  Supiot, 
the  widow  Melin,  &c.  The  various  Hates  of  any  diforder  arc 
always  pointed  out  by  the  (tare  of  the  urine;  and  the  trulr 
pra£lical  phyfician  will  there  obferve  Hgns  of  crudity  and  co::- 
to(^ion  which   will  direct  his  proceedings. 

Urine  is  like  wife  an  humour  intereding  to  be  known  on  ac- 
count of  the  various  ufes  to  which  it  is  applied  in  the  arts.  It 
was  from  this  fubflance  alone  that  phofphorus  was,  for  a  Ion  -^ 
time  extra£led  ;  it  is  to  this  fluid  that  we  owe  the  deveIo;Mment 
of  the  blue  colour  of  turnfole,  and  rhe  violet  of  archil ;  it  may  be 
fuccefsfuUy  employed  in  for.nin g  artincial  nitre-beds  ;  it  power- 
fully contributes  to  the  formation  of  fal  ammoniack;  it  may  be 
ufed  to  prepare  the  alkali  in  the  manufadlure  of  Piuflian  blue  ; 
and,  in  a  word,  it  may  be  applied  in  all  the  operations  wherein 
the  concurrence  of  an  animal  tiumour  is  required. 

Urine,  in  its  natural  (bate,  is  tranfpiren'f,  of  a  citron  vcKow 
colour,  a  peculiar  fmdl,  ,ind  a  filine  t-ifte. 

It  is  more  or  lefs  abundant,  according  to  the  feafons,  and  the 
flate  of  the  indiviJuiL  It  is  fulHcient  to  obferve,  on  this  fub- 
je("l:,  that  tranfpiration,  and  more  efpecially  perfpiHition  or 
fweat,  fupply  the  place  of  the  fecretion  of  urine  ;  and  tliat  con- 
fequently,  when  the  tranfpiration  ii  gre^t,  the  urine  is  net  abun- 
dant. 


^'ik 


563  Anal^fts  of  Urine. 

Phyficians  didinguifh  two  kinds  of  urine.  The  one  is  emiN 
ted  one  or  two  hours  after  drinking  ;  this  is  aqueous,  contains 
fcarcely  any  fahs,  and  has  neither  colour  nor  Imell  :  it  is  this 
which  is  evacuated  fo  pientifaliy  during  a  courfe  of  mineral  wa- 
ters. The  other  is  not  evacuated  until  after  the  functions  of 
fanguiiication  are  finiihed  :  and  may  be  called  Fseces  Sanguinis. 
This  is  all  the  chara*5lers  we  have  enumerated  and  alTigned  to 
urine.  It  is  carried  by  the  arteries  into  the  kidneys,  where  it  is 
feparated,  and  poured  into  the  receptacles  of  thcfe  organs, 
whence  it  pafles,  by  the  ureters,  into  the  bladder  ;  where  it  re- 
mains a  longer  or  Ihorter  time  according  to  the  habitude  of  the 
perfon,  the  nature  of  the  urine,  the  irritability  or  magnitude  of 
the  bladder  itfelf. 

The  urine  has  been  long  confidered  as  an  alkaline  fluid  :  but 
m  our  time  it  has  been  proved  to  contain  an  excefs  of  acid.  It 
appears  from  the  experiments  of  M,  BerthoUet — i.  That  this 
acid  is  of  the  nature  of  the  phofphorick  acid.  2.  That  the  urine  of 
gouty  perfons  contains  lefs  of  this  acid  ;  whence  he  conjeclures, 
with  reafon,  that  this  actd  retained  in  the  blood,  and  conveyed 
into  the  articulations,  produces  an  irritation,  and  confequently  a 
flux  of  humours,  which  caufe  pain  and  fwelling. 

The  analyfis  of  urine  by  diftillation  has  been  accurately  made 
by  various  chemifts,  but  more  efpecially  by  Rouelle  the  younger. 
Much  phlegm  is  obtained,  which  putrefies  with  the  greatefl  fa- 
cility, and  affords  ammoniack  by  its  putrefa6lion,  though  it  does 
not  itfelf  contain  that  fubftance.  Au  the  fame  time  a  fubftance 
Is  precipitated  of  an  earthy  appearance,  but  which  in  reality  is  a 
true  phofphate  of  urine.  It  is  this  fame  fait  which  forms  the 
fedlments  of  urine,  which  is  obfcrved  by  expofing  it  to  cold  dur- 
ing the  winter,  even  though  the  urine  be  of  a  perfon  in  perfe£l 
health.  When  urine  has,  by  a  fufficient  evaporation,  acquired 
the  confidence  of  fyrup,  it  need  only  be  expofed,  in  a  cool 
place,  to  obtain  cryftals,  in  which  analyfis  has  proved  the  exift- 
ence  of  the  phofphates  of  foda  and  of  ammoniack.  This  pre- 
cipitate of  cryftals  has  been  diftinguifhed  by  the  name  of  fufible 
fait,  native  fait,  microcofmick  fait.  Urine  may  be  deprived  of 
all  faline  matter  by  repeated  folutions,  filtrations,  and  evapora- 
tions •,  the  matter  which  adheres  to  thefe  cryftals,  and  of  which 
they  may  be  cleared  by  thefe  operations,  is  foluble  partly  in  al- 
cohol and  partly  in  water.  The  faponaceous  fubftance,  or  that 
•wii'ch  is  foluble  in  alcohol,  is  capable  of  cryftalHzation,  dries 
diiT'.cult:^,  and  affords  by  diftillation  a  fmall  quantity  of  oil, 
carbonate  of  ammoniack,  of  muriate  of  ammoniack,  and  the 
refidue  converts  fyrup  of  violets  to  a  green.  The  cxtradive 
principle  is  eafily  dried,  and  exhibits  the  fame  phenomena  in 
diftillation  as  animal  fubft.ances.     See  Rouelle. 


Analyfis  of  Urine,  ^6^ 

The  phenomena  exhibited  by  the  fpontaneous  decompoiitioa 
of  grine  are  Tcry  intcreding  to  be  known  ;  on  which  lubjedb 
an  excellent  memoir  of  Mr.  Halle  in  the  volume  of  the  Society 
of  Medicine  for  1779,  may  be  confulted.  Urine  left  to  itfelf 
foon  lofes  its  fmell,  which  is  iucceeded  by  afmell  of  ammoniack^ 
which  is  hkewife  diffipated  in  its  turn.  The  colour  becomes 
brovvnilh,and  the  fmell  fetid  and  naufeous.  We  are  indebted 
to  Mr.  Rouelle  for  a  valuable  obfervation — that  crude  urine, 
urina  poius^  prefents  very  different  phenomena  ;  and  that  it  be- 
comes covered  wiih  rnouldinefs,  like  the  exprefled  juices  of 
vegetables.  Putrefied  urine  has  much  lefs  acid  in  the  difengag- 
cdltate  than  when  it  is  frefli. 

The  fixed  alkalis  and  lime  difengage  much  ammoniack  from 
urine  by  decompofing  the  phofphate  oif  ammoniack. 

The, acids  deltroy  the  fmell  of  urine  by  combining  with  the 
ammoniack,  which  is  the  principal  vehicle  of  that  fmell. 

We  may  therefore  confider  urine,  in  its  natural  ftate,  as  wa- 
ter holding  in  folution  matters  purely  extractive,  and  phofphor- 
ick  or  muriatick  falts.  Thefe  phofphorick  falts  have  lime,  am- 
jnoniack,  or  f^da,  for  their  bafis  ;  we  fliall  take  a  flight  view  of 
each  in  particular. 

That  which  is  called  fufible  fait,  is  nothing  but  a  mixture  of 
all  the  falts  contained  in  urine,  clogged  with  the  extra'51ive  prin- 
ciple, All  the  ancient  chemifts  advifed  evaporation  and  repeat- 
ed filtration,  to  clear  them  from  this  animal  extract  \  but  MelTrs. 
Rouelle  and  the  Duke  de  Chaulnes  have  obferved,  that  great 
part  of  the  fait  is  difengaged  and  diffipated  by  thefe  operations 
to  fuch  a  degree  that  three  fourths  are  lofl.  To  avoid  moft  of 
this  lofs,  the  Duke  de  Chaulnes  advifes  folution,  filtration,  and 
cooling  in  well  clofed  veflels.  Two  (Irata  of  fait  are  then  ob- 
tained ;  the  upper  of  which  appears  to  have  the  form  of  fquare 
tables,  wherein  Rouelle  obferved  tetrahedral  prifms  flattened 
with  dihedral  fummits.  This  is  the  phofphate  of  foda  :  and  be- 
neath this  lies  another  fait  cryftallized  in  regular  fetrahedrai 
prifms,  and  is  the  phofphate  of  ammoniack. 

I.  The  phofphate  of  ammoniack  ufually  exhibits  the  form  of 
a  very  compreiled  tetrahedral  rhomboidal  prifm  :  but  this  form 
varies  much  \  and  the  mixtures  of  the  phofphate  or  muriate  of 
foda  caufe  an  infinity  of  modifications  in  it. 

The  tafte  of  this  fait  is  cool,  afterwards  urinous,  bitter  and 
pungent. 

This  falts  fwells  up  on  the  coals,  emits  a  ftrong  fmell  of  am- 
moniack, and  melts  by  the  blow  pipe  into  a  verv  fixed  and  very 
fufible  glafs.  '         ' 

4. .A 


57^  Ph&fphate  of  Soda. 

It  w;  f.'luble  in  water.  Five  parts  of  cold  water,  at  ten  degrees 
of  Reaumur,  diflblved  only  one  of  this  fait;  but  at  the  tempera- 
ture of  flxty  de^^rees  this  fait  is  decompofed,  and  a  portion  of  its 
acid  is  volatilized. 

It  ferves  as  a  flux  to  all  the  earths  ;  but  in  this  cafe  its  alkali 
is  dijsngaged,  and  the  phofphorick  acid  unites  with  the  earth,  as 
I  find  by  experiment.  Bergmann  propofed  it  as  a  flux.  The 
fixed  alkalis  and  lime-water  difengage  the  ammoniack. 

When  this  fait  is  heated  with  charcoal,  it  aflbrds  phofphorus- 

2.  The  phofphate  of  foda  was  made  known  in  1740  by 
Haupt,  under  the  name  of  fal  admirable  perlatum.  Hellot  be- 
fore him,  and  Pott  feventeen  years  after  him,  took  it  for  felen- 
ire.  MargrafF  gave  an  accurate  defcription  of  it  in  hir,  Memoirs, 
in  1745  ;  and  Rouelle  the  younger  defcribed  it  at  full  length  in 
1776,  under  the  name  of  fufible  fait  with  bafe  of  natrum.  AH 
agree  that  it  difl^^rs  from  the  preceding  in  not  affording  phof- 
phorus  with  charcoal. 

According  to  Roaelle,  its  cryftals  are  flattened  irregular  te- 
trahedral  prifms,  with  dihedral  fummits.  The  four  fides  of  the 
prim  are  two  irregular  alternate  pentagons,  and  two  long  rhom- 
bi  truncated  flopewife. 

When  expofed  to  heat  it  fufes,  and  affords  a  glafs  which  be- 
comes opaque  by  cooling. 

It  is  fofuble  in  difllUed  water  and  the  folution  turns  fyrup 
of  violets  green. 

It  does  not  aiTord  phoft^horus  with  charcoal. 

Lime  difen^ages  the  foda.  It  may  even  be  obtained  in  a  cauf- 
tick  ilate,  if  the  precipitation  be  effected  by  lime   water. 

Th-i  mineral  acids,  or  even  diftilled  vinegar,  decompofe  it  by 
feizing  irs  alkali.  Mr.  Froufl,  to  whom  we  are  indebted  for  all 
the  accurate  information  we  pofliefs  concerning  thefe  fubilances 
was  of  opinion,  that  the  bafe  to  which  the  foda  adhered  was  not 
the  phofporick  acid,  but  a  very  lingular  fait,  whofe  properties 
greatly  refemble  thofe  of  the  acid  of  borax.  He  found  this  fait 
in  the  mother  water,  after  having  decompofed  the  phofphate  of 
foda  by  the  acetou-^  acid,  and  obtained  the  acetite  of  foda  by 
cryilaiilzarion-  He  obtained  this  fame  fait  by  diffolving  and 
evaporating  the  refidue  of  the  dillillation  of  phofphorus.  One 
ounce  of  phofphorick  glafs  contains  five  or  ^\\  drams.  This  fait 
was  chara(fl:erifed  by  the  following  properties  : 

1.  It  cryftalllzes  in  parallelograms. 

2.  Its  lafle  is  alkaline,  and  turns  fyrup    of  violets  green. 

3.  It  fvvells  up  in  the  fire,  reddens,  and  melts. 

4.  It  efflorefces  in  the  air.  This  may  not  take  place  when 
the  phofporick  acid  has  not  been  fufficiently  decompofed  by  the 
diilillation  to  leave  the  alkali  difertgaged,  as  I  have   obferved. 


.^^% 


Calculus  of  the  Bladder,  5  7 1 

5.  Boiling  water  diflblves  fixgrosper  ounce. 

6.  It  afiifts  the  vitrification  of  earths.,  and  forms  a  perfeft 
glafs  with  filex. 

7.  It  decompofes  nitre  and  marine  fait,  and  feparates  their 
Rcids. 

8.  It  is  infoluble  in  alcohol. 

Mr.  Klapvoth  has  publiflied  in  Crell's  Journal  an  analyfis  of 
the  fufible  fait,  in  which  he  has  fliewn  that  the  pearly  fait,  or 
fait  of  Prouft,  is  merely  the  phofphate  offoda.  To  prove  this 
nothing  more  need  to  be  done  than  to  diffolve  this  fait  in  water 
and  to  add  a  folution  of  nitrate  of  lime.  The  nitrick  acid  feizes 
the  foda,  and  the  phofporick  acid  is  precipitated  with  the  lime. 
The  phofporic  acid  may  afterwards  be  feparated  by  means  of 
the  fulphrick  acid. 

If  the  phofphorick  acid  obtained  by  the    flow  combuilion  of 
phofphorus  be    faturated  with  foda  flightly  in  excefs,  the  fufibb 
fait  is  formed  ;  if   this  excefs  be    taken    up   by    vinegar,   gr   Vi 
more  phofphorick  acid    be   added,    the  fubllance  defcribed  by 
Proud  is  formed. 

The  phofphate  of  foda  is  not  decompofable  by  charcoal ;  and 
it  is  at  prefent  clearly  feen  why  the  fufible  fait  affords  but  little 
phofphorus  •,  and  why  Kunckel,  Margraaf,  and  orhers  recom- 
mended a  mixture  of  the  muriate  of  lead  ;  for  by  this  means 
the  phofpate  of  lead  was  formed,  which  permits  the  decompo- 
fition  of  the  phofphorick  acid,  and  affords  phofphorus. 

Concerning  the  Calculus  of  the  Bladder. 

■Paracelfus  made  fome  refearches  concerning  the  calculus  oi 
the  bladder  which  he  calls  duelech.  He  confiders  it  as  a  fub- 
itance  intermediate  between  tartar  and  (lone,  and  thinks  that  its 
formation  is  owing  to  the  modification  of  an  animal  refin  :  he 
fuppofes  it  to  be  abfolutely  fimilar  to  the    matter  of  the  gout. 

Vanhelmont  does  not  admit  of  this  analogy;  and  confideiT 
the  calculus  as  an  animal  coagulum  produced  by  the  falts  of 
urine,  and  a  volatile  earthy  fpirit.  Boyle  found  this  calculus  to 
be  compcfed  of  oil  and  volatile  fait.  Boerhaave  fuppoied  it  to 
confill  of  a  fubtle  earth,,  intimately  united  with  alkaline  volatile 
falts.  Hales  has  obferved  that  a  calculus  of  die  weight  of  two 
hundred  and  thirty  grains  afforded  fix  hundred  and  forty-five 
times  its  volume  of  air,  and  that  there  remained  only  a  calx  of 
the  weight  of  forty-nine  grains. 

Independent  of  this  chemical  information,  fome  phyficians, 
fuch  as  Alflcn,  De  Haen,  Vogel,  Meckel,  &c.  had  obferved  the 
folvent  powjer  of  foap,  lime-water,  and  alkalis. 


Syi  Calculus  of  the  Bladdi^^ 

But  we  poiTefled  no  accurate  ideas  on  this  fubje£l  until  it  was 
ferioufly  taken  up  by  Scheele  and  Bergmann.  Thebezoar  of  the 
bladder  is  formed  for  the  mod  part  of  a  peculiar  concrete  acid^ 
which  1\T.  De  Morveau  calls  the  Lithiafick  Acid.  (The  Ency- 
clopedic Methodique  may  be  confulted,  from  which  the  prefent 
article  is  an  extrail:.) 

The  calculus  is  partly  foluble  in  boiling  water.  The  lixivir 
um  reddens  the  tin6ture  of  turnfole  ;  and  by  cooling  depofites 
moft  of  what  it  had  difToIved.  The  cryftals  thus  feparated  are 
the  concrete  lithiafick  acid. 

Scheele  has  likewife  obferved — i.  That  the  fulphurick  does 
not  diflblve  the  calculus  unlefs  aiTifted  by  heat,  and  that  it  is 
then  converted  into  the  ftate  of  fulphureous  acid.  2.  That  the 
muriatick  acid  has  no  adion  upon  it.  3.  That  the  nitrick  acid 
diflblves  it  with  efFervefcence,.  and  difengages  nitrous  gas  and 
carbonick  acid.  This  folution  is  red;  it  contains  a  difengaged 
acid,  and  tinges  the  (kin  of  a  red  colour.  This  folution  is  not 
precipitated  by  the  muriate  of  barytes,  nor  rendered  turbid  by 
by  the  oxalick  acid.  4.  That  the  calculus  was  not  attacked  by 
the  carbonate  of  pot  a(h  ;  but  that  the  caudick  alkali  diflblved 
it,  as  well  as  the  volatile  alkali-  5.  That  one  thoufand  grains 
of  lime-water  diiTolved  5.37  by  mere  digeftion,  and  that  it  was 
again  precipitated  by  acids.  6.  That  all  urine  even  that  of  in- 
fants, held  a  fmall  quantity  of  the  matter  of  calculus  in  iolution  ; 
which  perhaps  may  be  the  caufe,  that  when  this  matter  finds  a 
nucleus  in  the  bladder,  it  more  eafily  encrufts  it.  I  have  {^tn 
a  calculus  with  a  large  plum  ftone  in  its  centre.  7.  That  the 
brick  coloured  depofition  from  the  urine  in  fevers,  is  of  the  na- 
ture of  the  calculi. 

Thefe  experiments  exhibit  feveral  important  confequences, 
with  regard  to  the  compofition  of  the  calculus,  and  the  proper- 
ties of  the  lithick  acid. 

The  calculus  contains  a  fmall  quantity  of  ammoniack.  Thrc 
coaly  refidue  of  the  combultion  indicates  an  animal  fubflance 
of  the  nature  of  jelly.  The  celebrated  Scheele  did  not  .find  it 
to  contain  a  particle  of  calcareous  earth  ;  but  Bergmann  pre- 
cipitated a  true  fulphate  of  lime,  by  poviring  ihe  falpliur'ck  in- 
to the  nitrous  folution  of  the  calculus.  He  admits  that  the 
lime  is  very  fmall  in  quantity,  as  it  rarely  exceeds  the  two  hun- 
dredth part  of  the  entire  weight.  The  fame  chemift  has  detect- 
ed a  white  fpongy  fubliance,  not  foluble  in  water,  nor  attacked 
by  fpirit  of  wine,  or  acids,  or  alkalis,  which  at  lad  affords  a  coal 
ot  difficult  incineration,  and  which  the  nitrick  acid  does  not  dif- 
folve,  even  in  the  Hate  of  afhes  ;  but  this  matter  exids  in  fo 
fmall  a  quantity,  that  he  could  not  procure    enough  to  exaniin<? 


Jtrlhriiich    C<mcriti0ns,  5^3 

it.  The  calculus  is  not  tiierefore  analogous  to  bones  in  its  na- 
ture ;  neither  is  it  a  pholphate  of  lime,  as  has  been  pretended. 
Theie  are  the  refults  qi  the  chemifts  of  the  north  ;  but  I  mull 
obferve  that,  after  having  deccmpofed  many  calculi  by  the  cauf- 
tick  alkali,  I  have  precipitated  lime,  and  formed  phofphates  of 
pota^. 

Some  phyficians,  fuch  as  Sydenham,  Cheyne,  Murray,  &c. 
Jiave  thought  that  the  arthritick  concretions  uere  of  the  fame 
nature  as  the  calculus.  The  ufe  which  Boerhaave  made  of  al- 
kalis in  the  gout  ;  the  virtues  admitted  by  Fred.  Ilcflman  in 
the  thermal  waters' of  Carlefbad,  which  contain  foda,  with  an 
cxcefs  of  carbonick  acid  ;  the  authority  of  Springsfeld,  who  af- 
ferts  that  the  calculus  is  very  fpeedily  diflblved  in  thtfe  waters, 
even  in  the  uripe  of  thofe  wlio  drink  t};em  •,  the  fuccefs  of 
lime  water,  ufed  by  Alfton  in  the  gout — all  confpire  to  give 
fome  credit  to  the  opinion  of  thefe  early  phyficians.  But  the  fol- 
lowing experiments  do  not  agree  with  this  notion. 

Vanfwieten  affirms  that  the  arthritick  concretion  never  ac- 
quires the  harfhnefs  of  the  calculus.  Pinclli  (Philof.  Tranf.) 
diftilled  in  a  retort  three  ounces  of  the  arthritick  matter  collefled 
from  the  articulations  of  feveral  gouty  perfons  j  and  he  obtain- 
ed ammoniack,  with  fome  drops  of  oil,  the  refidue  weighing 
two  gros.  This  refidue,  which  was  foluble  in  the  muriatick, 
fulphurick  and  acetous  acid,  was  not  attacked  by  volatile  alkali. 
An  obfervation  of  Mr.  Roering  was  publifhed  in  the  memoirs  of 
the  academy  of  Stockholm  for  1783,  which  afcertains  that  the 
concretions  expectorated  by  an  old  man  fubjed;  to  the  gout, 
were  found  to  be  of  the  nature  of  bone,  or  phofphatc  of  lime. 
But  one  of  the  newefl  and  moft  important  facts  is  that  of  Wat- 
ion,  in  the  Medical  Communications  of  London,  vol.  i.  i  7S4. 
He  concludes,  from  the  examination  of  the  arthritick  concretions 
of  a  gouty  body,  that  this  fubftance  is  very  different  from  the 
matter  of  the  calculus,  £n\cc  it  is  foluble  in  the  fynovia,  and  ea- 
fily  mixes  with  oil  and  water,  which  the  calculus  does  not. 

It  follows  from  our  obfervations  on  the  lithick  acid,  that  this 
acid  is  concrete,  and  fparingly  foluble  in  water  ;  that  it  is  de- 
compofed,  and  partly  fublimed  by  di ([illation.  This  acid  de- 
compofes  thenitrick  acid,  unites  with  envihs,  alkalis,  and  me- 
taiiick  oxides.  It  yield-  its  bafe-^  lo  the  ^veaked  vegetable  acids 
notexcepring  the  carbonick. 


^m- 


574  Dif cover y  of  Phofphorus, 


CHAPTER    IX. 


Concerning  Phofphorus. 

PHOSPHORUS  is  one  of  the  moft  aftonlftiing  produas  of 
chemlftry.  It  is  pretended  that  traces  of  the  knowledge  of  this 
fubflance  exift  in  the  writings  of  the  earlieft  chemifts  :  but  the 
moil  pofitive  information  we  poiTefs  on  this  fubje6l  is  found  in 
thehiftory  given  by  Leibnitz,  in  the  Melanges  de  Berlin  for 
1710.  He  gives  the  difcovery  to  Brandt,  a  chemift  of  Hamburgh, 
who  during  a  courfe  of  experiments  upon  urine,  with  a  view  of 
extracting  a  fluid  proper  to  convert  filver  into  gold,  difcovered 
phofphorus  in  the  year  1667.  He  communicated  his  difcovery 
-  to  Kraft,  who  fhowed  it  to  Leibnitz,  and  being  afterwards  in 
England  he  communicated  it  to  Boyle.*  Leibnitz  caufed  the 
firll  inventor  to  be  introduced  to  the  Duke  of  Hanover,  before 
whom  he  performed  the  whole  operation  ;  and  a  fpecimen  of  the 
phofphorus  was  fent  to  Huygens,  who  fnowed  it  to  the  Acade- 
Biy  of  Sciences  at  Paris. 

It  is  faid  that  Kunckel  had  alTociated  himfelf  with  Kraft  to 
purchase  the  procels  from  Brandt.  But  Kunckel  having  been 
deceived  by  Kraft,  who  kept  the  fecret  to  himfelf,  knowing  that 
urine  was  made  ufe  of,  fet  to  work,  and  difcovered  a  procefs 
for  making  the  fubftance  *,  and  it  is  this  which  led  chemifts  to 
call  it  by  the  name  of  Kunckei's  Phofphorus. 


*  As  Boyle  comr /;nicated  tiie  procefs  for  making  phofphorus  to  the 
Royal  Society  as  a  dncovery  of  his  own,  and  it  is  entered  asfuch  in  tiie 
J^h'Jolophica!  Tranfa<5aons,  i  cannot  avoid  animadvertirg  on  this  impeach- 
ment of  his  integrity,  which  is  copied  from  one  chemical  book  into  ano- 
ther. It  is  grounded  on  no  better  foundation  than  the  afiertion  of  Kraft, 
H  dealer  in  lecrets,  who,  after  having  deceived  his  friend  Kunckd,  affo- 
.ciaied  with  him  for  the  purchafe  of  this  fecret.  I_  might  infill,  in  defence 
of  the  candour  and  otliervvife  unimpeached  integrity  of  Boyie,  that  his  af- 
fevtion  ought  inliniteiy  to  outweigh  that  of"  the  otiier.  Not  toinfift,  how- 
ever, upon  this,  it  may  be  noticed  that  this  new  and  famous  produdt  wa-s 
known  to  have  been  extracted  from  urine  ;  that  Kunckel  is  univerialiy  ad- 
mitted as  the  difcovever,  from  his  having  formed  it  upon  no  fuller  inform- 
a'cion  than  diis ;  that  Boyle  might  with  equal  probability  be  admitted  tf> 
have  difcovered  it  in  the  fame  manner,  and  upon  information  equHlly 
ilight  ;  ai:d  that  the  probability  of  this  is  rendered  incomparably  greater 
bythe  confideraticn  that  none  of  thefe  chemifts  made  any  complicated 
experiment?,  but  merely  applied  the  force  of  lire  to  urine  until  this  product 
at  lail  came  over.     T. 


Procefs  for  making  Phofphwus,  ^*j^ 

Though  the  procefs  was  rendered  publick,  Kunckel,  and  a 
German  called  Godefred  Hatwith,f  were  the  only  perfons  who 
prepared  phofphorus  for  a  long  time.  It  was  not  till  the  yeat* 
1737,  that  it  was  made  in  the  laboratory  of  the  Royal  Garden 
at  Paris.  A  foreigner  executed  this  operation  in  the  prefence 
of  MefTrs.  Hellot,  D'u  Fay,  GsofTroy,  and  Du  Hamel.  An  ac- 
count of  the  operaiion  may  be  (csn  in  the  volume  of  the  Acad- 
emy for  1737-  Hellot  has  collecfted  all  the  effential  circum- 
ftancen.  Margraaf,  in  th'j  year  1743,  publiflied  a  new  and 
more  eafy  method,  which  has  been  followed  until  Scheele  and 
Ghan  taught  us  to  obtain  it  from  bones. 

The  procefs  of  Margraaf  con fi fts  in  mixing  the  muriate  of 
lead,  which  remains  after  the  diftillation  of  four  pounds  of  min- 
ium and  two  of  fal  ammoniack,  with  ten  pounds  of  the  extraft 
of  urine  of  the  confidence  of  honey.  Half  a  pound  of  charcoal 
in  powder  is  added  ;  the  mixture  is  dried  in  an  iron  pot  until 
it  is  reduced  to  a  black  powder.  This  powder  is  to  be  put  into 
a  retort  ;  and  the  volatile  alkali,  the  fetid  oil,  and  the  hi  am- 
moniack, diftilled  ofl-.  The  refidue  contains  the  phofphorus. 
It  is  aff.iyed  by  throwing  a  fmall  quantity  on  hot  coals  :  if  it 
emits  a  fmell  of  garlick,  and  a  phofphorick  flame,  it  is  to  be  put 
into  a  good  earthen  retort,  and  diftilled.  Much  more  phofpho- 
rus is  obtained  by  this  than  by  the  old  procefs  ;  and  this  de- 
pends on  the  addition  of  the  muriate  of  lead  by  Margraaf,  which 
decompofes  the  phofphate  of  foda,  forming  a  phofphate  of  lead, 
which  affords  phofphorus  jawhereas  the  phofphate  of  foda  is  not 
decompofable  by  charcoal.  The  famous  chemift  of  Berlin  has 
likewife  proved  that  it  was  the  fufibie  fait  of  urine  which  affords 
the  phofphorus. 

Mr.  Gahn  publifhed  in  the  year  1769,  that  the  earth  of  cal- 
cined bones  confifted  of  lime  united  with  the  acid  of  urine  ;  but 
Scheele  wa:>  the  lirft  to  prove  that  by  decompodng  this  fait  of 
bones  by  the  nitrick  and  fulphurick  acids,  evaporating  the  refi- 
<lue  in  which  the  phof,)horick  acids  exift  in  a  difengaged  ftate, 
•and  diftilling  theextrat^  with  powder  of  charcoal,  phofphorus 
is  obtained.  Thefe  circumftances,  related  by  Bergmana  himfelf 
in  his  notes  to  the  Chcmiflry  of  SchefFer,  attribute  to  Scheele 
the  difcovery  of  extracting  phofphorus  from  bones.  It  was  not 
until  the  year  1775  that  the  procefs  was  publifhed  in  the  Ga- 
zette Salutaire  de  Bouillon.  Additions  and  improvements  have 
been  fucceffively  made  in  this  procefs,  of  which  accounts  may  be 
fcen  in  the  DiClionnaire  Encyclopedique. 

The  procefs  which  has  moil  conllantly  fucceeded  with  me,  is 
the  following  : 

t  Spelled  lianckwitz  by  moH  authors.  He  was  inilru(5l2d  by  Boyle,  T- 


57^  Phofphorus  and  Phofphorich  Glafs, 

The  hardeft  bones  are  felecled  and  burned.  By  this  combuf- 
tian  rhe  external  part  becomes  white,  while  the  internal  part  is 
blackiih. 

Thef^  burned  bon3s  muft  then  be  pulverized,  and  put  into  a 
turine,  or  in  a  round  hooped  wooden  veflel.  H.df  the  weiG:ht  of 
oil  of  vitriol  is  then  to  be  poured  on,  and  conftantly  (lirred. 
During  the  agitation  a  co'.iiiderable  heat  is  excited.  The  mix- 
ture muft  be  left  in  a  digeftion  for  two  or  three  days  :  after 
which,  water  muft  be  gradually  added,  and  ftirred.  I  digefl 
this  laft  mixture  upon  the  hre,  in  order  to  increafe  the  folvent 
power  of  the  water. 

The  water  of  the  lixivium  is  then  to  be  evaporated  in  velTels 
of  Itone  ware,  filver,  or  copper.  Mr.  Pelletier  recommends 
this  laft  metal ;  becaufe,  according  to  him,  the  phofphorick  acid 
does  not  attack  copper.  The  evaporation  mud  be  carried  to  dry- 
nefs  :  more  boiling  water  muft  be  poured  on  the  refidue  ;  and 
this  wafning  muft  be  continued  until  the  matter  be  exhaufted, 
which  may  be  known  by  the  water  being  no  longer  tinged  yel- 
low. All  theie  waters  are  to  be  evaporated,  and  afford  an  ex- 
traa. 

To  feparate  the  fulphate  of  lime,  the  extrafl  muft  be  diffblved 
in  the  leaft  pofTible  quantity  of  water,  then  filtered,  and  the  fait 
remains  on  the  filtre.  This  extradt  may  be  mixed  with  powder 
6f  charcoal,  and  diftilled ;  but  I  prefer  converting  it  into  ani- 
mal glafs  :  for  which  purpofe  I  put  the  extrafl  into  a  large  cru* 
cible,  and  urge  the  fire.  It  fwells  up^t  firft,  but  at  laft  fettles  ; 
and  at  that  inftant  the  glafs  is  made.  This  glafs  is  white,  of  a 
milky  colour.  Becher  was  perfecftly  acquainted  with  it ;  but 
concealed  his  procefs,  on  account  of  the  abufes  which,  according 
to  him  might  be  made  of  it — propter  varios  ahufus.  He  teiis  us, 
in  proper  terms,  homo  vitrum  ejly  et  in  vitrum  redlgi  potejiy  ftcitt 
et  omnia  animalia.  He  regrets  that  the  Scythians,  who  drank  out 
of  difgufting  fculls,  were  not  acquainted  with  the  art  of  convert- 
ing them  into  glafs.  He  (hews  that  it  would  be  poflible  to 
form  a  feries  of  one's  anceftors  in  glafs,  in  the  fame  manner  a« 
we  pofTcfs  them  in  painting,  &:c. 

I  obfervedonce  to  my  great  aftonifhment,  that  the  phofphor- 
ick glafs  I  had  juft  made,  emitted  very  ftrong  eledlrick  fparks  ; 
thefe  flew  to  the  hand  at  the  diftance  of  two  Inches.  I  exhibit- 
ed this  phenomenon  to  my  audience  of  pupils.  This  glafs  loft 
■the  property  in  two  or  three  days,  though  preferved  in  a  capfule 
of  common  glafs. 

It  fometimes  happens  that  this  glafs  is  deliquefcent,  bat  it  is 
then  acid  ;  and  this  circumitance  arifes  from  too  large  a  quan- 


Diflillatiottylsfcof  "Phofphorus.  577 

tity  of  fulphurlck  acid,  or  from  this  acid  not  having  been  fatur- 
ated  by  a  digeftion  of  fufficient  continuance. 

I  have  likewife  obtained  glafs  of  the  colour  of  turquoife,  when 
I  performed  the  evaporation  in  copper  veflels.  .    * 

This  glafs  may  be  deprived  of  the  bubbles  it  ufually  contains, 
by  keeping  it  for  a  time  in  a  violent  heat ;  it  is  then  tranfparent, 
and  may  be  cut  like  a  diamond.  According  to  Crell,  its  fpeci- 
fick  gravity  is  to  that  of  water  as  three  to  one,  while  that  of  di- 
amond is  as  three  and  a  half  to  one.  This  glafs,  is  infoluble  in 
water,  &c.  A  &eleton  of  nineteen  pounds,  burned,  affords  five 
pounds  of  phofphorick  glafs: 

I  pulverize  this  glafs,  mix  it  with  equal  parts  of  powder  of 
charcoal,  put  it  into  a  porcelain  retort  well  coated,  ^the  beak  o£ 
which  1  partly  plunge  into  the  water  of  the  receiver,  fo  that  noth- 
ing can  efcape  but  air  or  phofphorick  gas.  I  adapt  a  large  tube 
to  the  tubulure  of  the  receiver,  and  plunge  it  into  a  veflel  filled 
with  water.  Tfie  fire  being  raifed  by  degrees,  the  phofphorus 
comes  over  the  moment  the  mixture  is  ignited.  The  phofphorus 
fublimes,  partly  in  the  form  of  a  fume  which  congeals  ;  and  is 
precipitated  upon  the  furface  of  the  water,  partly  in  the  form 
of  inflammable  gas,  and  partly  refembling  melted  wax,  which 
drops  in  beautiful  tranfparent  tears  from  the  neck  of  the  retort. 
The  theory  of  this  operation  is  eafily  explained.  The  phofphor- 
ick acid  is  difplaced  by  the  fulphurick  acid,  as  is  (hewn  by  the 
large  quantity  of  fulphate  of  lime  which  is  obtained.  All  the 
other  operations  tend  only  to  concentrate  this  phofphorick  acid 
which  is  ftill  combined  with  other  animal  fubflances,  and  the 
diftillation  with  charcoal  decompofes  the  phofphorick  acid  ;  its 
oxigene  unites  with  the  coal,  and  affords  a  carbonick  acid,  while 
the  phofphorus  itfelf  becomes  difengaged. 

To  purify  the  phofphorus,  a  piece  of  chamois  leather  is  moifl- 
ened,  and  the  mafs  of  phofphorus  is  put  into  it.  This  being 
immerfed  in  a  vefTel  of  boiling  water,  the  phofphorus  melts,  and 
and  is  paffed  through  the  fkin  like  mercury.  The  fkln  cannot 
be  ufed  more  than  once;  the  phofphorus,  which  might  be  paffed 
a  fecond  time,  would  become  coloured.  This  procefs  was  con- 
trived by  Mr.  Pelletier. 

In  order  to  form  phofphorus  into  flicks,  a  funnel  with  a  long 
neck  may  be  ufed,  the  lower  orifice  being  clofed  with  a  fmall 
cork,  or  piece  of  foft  wood.  The  funnel  is  then  to  be  filled 
with  water,  and  phofphorus  put  in  it ;  and  this  being  plunged 
in  boiling  water,  the  heat  is  communicated  to  that  of  the  funnel  ; 
and  melts  the  phofphorus,  which  runs  into  the  neck,  and  takes 
that  form.  The  funnel  is  :hen  removed  into  a  veflel  of  cold' 
water  ;  and  when  the  phofphorus  is  perfectly  cooled,  the  cork' 
4...B 


57^  Pfoperties  ef  Phofphorous, 

is  taken  out,  and  the  phofphorus  thruft  out  of  its  mould  with  a 
fmall  piece  of  wood. 

Phofphorus  is  kept  under  water.  After  a  certain  time  it  lo- 
fes  i,ts  tranfparency,  becomes  covered  with  a  white  powder,  and 
the  water  is  acidulated.* 

In  whatever  manner  phofphorus  may  be  made,  it  is  always 
orife  and  the  fame  fubftance,  chara6lerized  by  the  following 
properties:  It  is  of  a  flefli  colour,  and  evidently  tranfpareiit. 
It  has  the  confidence  of  wax  5  and  may  be  cut  in  pieces  with  a 
knife,  or  twifted  afunder  with  the  fingers  ;  in  which  laft  cafe 
the  precaution  mud  be  taken  of  frequently  plunging  it  into  wa- 
ter, to  prevent  its  taking  fire. 

When  phofphorus  is  placed  in  contact  with  the  air,  it  emits 
a  white  fume.  It  is  luminous  in  the  dark  ;  and  a  folid  ftick  of 
phofphorus  may  be  ufed  to  write  with,  like  a  crayon.  The 
marks  are  vifible  in  the  dark  ;  and  this  means  has  often  been 
ufed  to  create  fear  and  aftonifhment  in  the  minds  of  the  igno- 
rant. 

When  phofphorus  is  expofed  to  twenty  fourf  degrees  of  heat 
it  takes  fire  with  decrepitation,  burns  with  a  very  bright  flame, 
and  emits  a  very  abundant  white  fume  which  is  luminous  in  the 
dark.  The  refidue  of  thecombuftion  is  a  red  cauftick  fubftance 
which  attracts  the  humidity  of  the  air,  and  becomes  refolved 
into  a  liquor.  This  is  the  phofphorick  acid,  which  we  (hall 
proceed  to  treat  of. 

Mr.  Willon  affirms  that  the  folar  rays  fet  fire  to  phofphorus  \ 
and  proves  that  this  flame  has  the  colour  proper  to  the  phofpho- 
rus, and  not  that  of  the  ray  itfelf. — Letter  of  Mr.  Wilfon  to 
Mr  Euler,  read  at  the  Royal  Society  of  London  in  June,  1779. 

An  advantageous  ufehas  lately  been  made  of  the  combuftible 
property  of  phofphorus,  to  procure  fire  conveniently,  and  in  all  fitu- 
ations,  by  means  of  phofphorick  tapers  or  matches,  and  the  phi- 
lofophical  bottles,  the  method  of  making  which  we  (hall  pointout. 

*  This  fl'jw  acidification  of  the  phofphorus  feems  to  be  reverfed  by  the 
fun's  light.  Sticks  of  phofphorus,  which  had  become  covered  with  a 
white  powder,  were  expofed  under  water  to  the  fun's  light,  which  con- 
verted them  to  an  oiangc  yellow  colour  in  fuch  parts  as  were  aded  upon 
by  the  dired  light.  This  fad  appears  to  be  of  the  fame  nature  as  the  col- 
ouring of  the  nitrous  acid,  and  other  fimilar  phenomena.      T. 

f  Twenty-four  degrees  of  Reaumur  anfwer  to  eighty-fix  of  Fahrenheit. 
The  vivid  combuftion  of  phofphorus  takes  place  at  different  temperatures* 
according  to  its  purity  ;  but  the  prefent  is  very  low.  By  taking  phof- 
phorus into  a  freezing  atmofphere,  its  faint  flame  difappears,  and  it  feems 
to  require  a  temperature  of  iixty  degres  to  revive  it.  I  found  the  vivid 
combuftion  to  take  place  at  one  hundred  and  fixty  degrees.    T. 


Phofphorick    Bougigf-  579 

1 .  The  mod  fimplc  procefs  for  making  the  phofphorick  match- 
es, confifts  in  taking  a  glafs  tube,  four  inches  long  and  one  line 
ill  diameter,  clofed  at  one  end.  A  fmall  quantity  of  phofpho- 
rus  is  introduced  into  the  tube,  and  puflied  to  its  further  end  ; 
after  which  a  taper  covered  with  a  fmall  quantity  of  wax  is  in- 
troduced into  the  fame  tube.  The  open  end  is  then  hermeti- 
cally fealed,  and  the  other  end  is  plunged  into  boiling  water. 
The  phofphorus  melts,  and  fixes  itfelf  upon  the  match. 

A  line  is  drawn  at  one  third  of  the  length  of  the  tube,  with  a 
flint,  that  it  may  be  broken  as  occafion  may  require. 

The  match  is  to  be  drawn  out  quickly,  to  enflame  the  phof- 
phorus. 

The  procefs  of  Mr.  Lewis  Pey la,  to  make  the  inflammable 
bougies,  confifl:  in  taking  a  glafs  tube,  five  inches  long  and  two 
lines  wide,  one  end  of  which  is  fealed  with  the  blow  pipe.  Small 
tapers  of  wax  are  prepared  with  three  double  threads  of  cot- 
ton twifted  together.  The  extremity  of  the  match  or  taper  is 
half  an  inch  long,  and  muft:  not  be  covered  with  wax. 

A  piece  of  lead  is  laid  in  a  faucer  filled  with  water  ;  and 
upon  this  the  phofphorus  is  cut,  beneath  the  water,  into  frag- 
ments of  the  fize  of  a  grain  of  millet.  One  of  thefe  grains  is 
to  be  dried,  and  introduced  into  the  tube  of  glafs  ;  after  which 
the  fortieth  part  of  a  grain  of  very  dry  fulphur  is  to  be  added, 
riiat  is  to  fay,  half  the  weight  of  the  phofphorus.  One  of  the 
bougies  is  then  taken,  and  its  extremity  dipped  in  very  clear  oil 
of  wax.  If  too  large  a  quantity  rifes,  it  muft  be  dried  with  a 
cloth. 

The  match  is  introduced  into  the  tube  with  a  turning  or  twifl:- 
ing  motion  between  the  fingers. 

The  bottom  of  the  tube  muft  then  be  plunged  in  boiling  wa- 
ter, to  foften  the  phofphorus  ;  obferving  to  keep  it  no  longer 
than  three  or  four  feconds  in  the  water. 

The  other  extremity  of  the  tube  is  afterwards  fealed. 

Thefe  bougies  muft  be  kept  in  a  tin  tube,  to  avoid  tiie  danger 
of  inflammation. 

2.  To  form  the  phofphorick  bottles,  a  glafs  bottle  is  heated 
by  fixing  it  in  a  ladle  full  of  fand,  and  two  or  three  fmall  pieces 
of  phofphorus  are  then  introduced  into  it.  A  fmall  red  hot  iron 
wire  is  ufed  to  ftir  the  phofphorus  about,  and  caufe  it  to  adhere 
to  the  internal  furface  of  the  bottle,  where  it  forms  a  reddilh 
coating.  The  heated  wire  is  introduced  repeatedly  ;  and  when 
all  the  plwfphorus  is  thus  diftributed  within  the  bottle,  it  is  left 
open  for  a  quarter  of  an  hour,  and  afterwards  corked.  When 
this  is  ufed,  a  contmon  match  tipped  with  fulphur  is  introduced 
into   the  bottJe,  turned  round  and  quickly  drawn  out.      The 


580  Habitudes  of  Phofphon4S. 

phofphorus  which  fticks  to  the  fulphur  takes  fire,  and  lights  the 
match. 

The  theory  of  this  phenomenon  depends  on  thecircumftance 
that  the  phofphorus  is  ftrongly  dried,  or  half  calcined,  and 
needs  only  the  contact  of  air  to  fet  it  on  fire. 

Phofphorus  is  foluble  in  oils,  more  efpecially  the  volatile  oils, 
which  then  become  luminous.  If  this  folution  be  kept  in  a  bot- 
tle, a  phofphorick  flafli,  which  emits  a  fmall  quantity  of  light, 
will  be  feen  every  time  the  bottle  is  opened.  The  oil  of  cloves 
is  ufed  in  this  operation.  The  combination  of  phofphorus  and 
oil  appears  to  exift  naturally  in  the  glow-worm,  lampyris  fplen- 
didula  Linnsei.  Forfter  of  Gottingen  obferves,  that  the  (hining 
matter  of  the  glow-worm  is  hquid.  If  the  glow-worm  be  crulli- 
ed  between  the  fingers,  the  phofphorefcence  remains  on  the  fin- 
ger. Henckel  reports  in  the  eighth  dilTertation  of  hisPyritolo- 
gia,  that  one  of  his  friends,  of  a  fanguine  temperament,  after 
having  danced  much,  perfpired  to  fuch  a  degree  that  he  thought 
his  life  in  danger.  While  he  undrefled,  traces  of  phofphorick 
flame  were  feen  on  his  fliirt,  which  left  yellow  red  Ipots  behind 
them,  refembling  the  refidue  of  burned  phofphorus  :  this  light 
was  long  vifible. 

A  phofphorick  gas  maybe  extracted  from  phofphorus,  which 
takes  fire  by  the  mere  contact  of  the  air.  Mr.  Gengembre  has 
fhewn  the  method  of  extracting  it,  by  digefting  alkalis  upon  it, 
(Memoir  read  to  the  academy  at  Pans  the  3d  of  May,  1783) ; 
and  at  the  fame  time  I  (hewed  that  it  might  be  extra£ted  by 
means  of  acids,  which  are  decompofed  upon  phofphorus.  I 
have  likewife  taken  notice,  in  my  Memoir  upon  the  decompofi- 
tion  of  the  nitrick  acid  by  phofphorus,  that  when  the  acid  is. 
digefted  upon  it,  a  gas  efcapes,  which  takes  fire  in  the  receiver, 
and  has  feveral  times  afforded  me  the  appearance  of  flafhes  of 
lightning  ftriking  through  the  cavity  of  the  veflels.  But  this 
phenomenon  difappeared  as  foon  as  the  vital  air  was  abforbed. 

It  is  to  the  difengagement  of  a  gas  of  this  nature  that  we 
may  attribute  the  ignis  fatui  which  plays  about  burying  grounds, 
and  generally  in  all  places  where  animals  are  buried  and  putrefy. 
It  is  to  a  fimilar  gas  that  we  may  refer  the  inflammable  air 
which  conftantly  burns  in  certain  places,  and  upon  the  furface  of 
certain  cold  fprings. 

Phofphorus  is  found  in  the  three  kingdoms.  Mr.  Gahn  found 
the  phofphorick  acid  in  lead.  Siderice  in  a  phofphorus  of  iron. 
The  feeds  of  rocket,  of  multard,  of  garden  crefles,  and  of  wheat, 
treated  by  Mr.  Margraaf,  afforded  him  a  fine  phofphorus.  Mr. 
Meyer,  of  Settin  has  announced,  in  the  Chemical  Annals  of 
Crell  for  the  year  1784,  that  the  green  refinous  part  of  the  leaves 


Decompofition  of  Phofphorus,  581 

of  plants  contains  the  phofphorlck  acid.  Mr.  Pilatr^  du  Rozier 
renewed  the  opinion  of  P.ouelle  in  1780,  (Journal  de  Phyfique 
for  November,)  who  confidered  the  phofphorick  acid  as  anala- 
gous  to  that  of  mucilaginous  bodies  ;  and  he  affirms  that  the  diftil- 
lation  of  pyrophorus  affords  five  or  fix  grains  of  phofphorus  in  the 
ounce.  The  phofphorick  acid  exifts  in  urine,  bones,  horns,  Sec.  M. 
Maret  by  treating  tv/elve  ounces  of  beef  by  combuftion,  obtained 
three  gros  of  tranfparent  phofphorick  glafs.  M.  Crell  obtained 
it  from  beef  fuet  and  human  fat  •,  M.  Hankwitz  from  excre*. 
ments  ;  Leidenfroft  from  old  cheefe  j  Fontanafrcmfifh's  bones  ; 
Bernaird  from  egg  fliells,  &c.  Meiirs.  Macquer  and  M.Struve 
found  the  phofphorick  acid  in  the  gailrick  juice. 

The  moit  intereiling  combination  of  phofphorus  is  thatwhicl;i 
it  forms^with  vital  air.  This  is  always  the  phofphorick  acid  ; 
but  the  acid  appear?  to  be  modified  by  the  manner  in  which  it 
is  made. 

Phofphorus  unites  with  the  oxigene — i .  By  deflagration,  or 
the  rapid  combuftion.  2.  By  the  flow  combuftion.  3.  In  the 
humid  way,  more  efpecially  by  the  decompofition  of  the  nitrick 
acid. 

1.  If  phofphorus  be  expofed  to  a  dry  heat  of  twenty-four  de- 
grees, it  takes  fire,  emits  a  white  denfe  fume,  and  leaves  a  red- 
difli  refidue,  which  powerfully  attra£l:s  the  humidity  of  the  air, 
and  becomes  refolved  into  a  liquor.  This  combuftion  may  be 
performed  under  glafs  vefTels  in  which  cafe  white  flocks  are  de- 
pofited  on  the  fides  of  the  glafs,  which  refolve  into  a  liquor  by 
the  contad  of  moift  air,  and  form  the  phofphorick  acid.  Care 
is  taken  to  introduce  an  additional  quantity  of  vital  air  when  the 
combuftion  of  the  phofphorus  has  not  been  completed. 

M.  Lavoifier  has  burned  phofphorus,  by  the  alTiftance  of  a 
burning  glafs,  under  a  veifel  plunged  in  mercury  (Memoirs  of  the 
Royal  Academy  of  Sciences,  1777.) 

Margraaf  had  obferved  that  air  is  abforbed  in  this  operation. 
M.  Morveau,  in  the  year  1772,  had  declared  the  fame  from  his 
own  experiments  ;  and  Fonrana  proved  that  phofphorus  abforbs 
and  vitiates  air,  like  every  other  combuftible  fubftance.  Mefl*. 
Lavoifier  and  De  la  Place  found  that  forty-five  grains  of  phof- 
phorus abforbed  65.62  of  vital  air. 

The  acid  obtained  by  this  m.eans  is  impure.  It  always  con- 
tains phofphorus  in  folution,  not  faturated  with  oxigene. 

2.  Phofphorus  is  moft  completely  decompofcd  by  the  flow 
combuftion.  For  this  purpofe  the  neck  of  a  glafs  funnel  is  in- 
ferted  into  a  bottle,  and  fticks  of  phofphorus  are  difpofed  round 
in  the  funnel,  fo  as  not  to  touch  each  other  ;  a  fmall  piece  of 
giafs  tube  being  put  into  ilic  neck,  to  prevent   their  falling 


582  ProperitN  of  Phofphoricl  Acid. 

through.  A  paper  is  tied  6ver  the  funnel.  The  phofphorus 
is  flowly  decompofed  ;  and,  as  it  becomes  converted  into  a  fluid, 
it  flows  into  the  bottle,  where  it  forms  a  liquid  ^inthout  fmell  or 
colour.  This  acid  almoft  always  retains  a  Imall  quantity  of  un- 
decompofed  phofphorus,  from  which  it  may  be  cleared  by  digef- 
ting  alcohol  upon  it,  which  diflblves  the  phofphorus  without 
volatilizing  the  acid. 

One  ounce  of  phofphorus  produces  in  this  manner  three  oun- 
ces of  phofphorick  acid. 

3.  The  nitrick  acid  may  be  decompofed  by  digeftion  upon 
phofphorus.  The  nitrous  gas  diflipated ;  and  the  oxigene  re- 
mains united  to  the  phofphorus,  with  which  it  forms  phofphor- 
ick acid.  When  the  nitrick  acid  is  very  concentrated,  the  phof- 
phorus takes  fire,  and  burns  at  its  furface.  I  publifhed  this 
procefs,  with  all  the  circumftances  of  the  operation,  in  1780, 
the  fame  year  in  which  the  excellent  Memoir  of  M.  Lavoifier 
on  the  fame  queftion  was  printed,  and  of  which  I  had  then  no 
knowledge. 

The  water  in  which  phofphorus  is  kept,  contra61:s  acidity  in 
the  courfe  of  time  ;  which  fhews  that  the  water  itfelf  is  decom- 
pofed, and  yields  its  oxigene  to  the  phofphorus. 

Phofphorus  precipitates  fome  metallick  oxides  from  their  io- 
Jutions  in  the  metallick  {late.  It  is  obferved  that  acid  is  formed 
in  this  operation  ;  which  proves  that  the  oxigene  quits  the  met- 
al to  unite  with  the  phofphorus. 

The  phofphorick  acid  s  clear,  inodorous,  without  being  cor- 
rolive.  It  may  be  concentrated  to  drynefs.  Crell  having  con- 
centrated it  to  drynefs,  found  its  fpecifick  gravity,  compared 
with  water,  to  be  as  3.  i. 

This  acid  is  very  fixed.  If  it  be  concentrated  in  a  mattrafs, 
the  water  is  firft  difliipated,  a  fmell  of  garlick  is  foon  perceived, 
which  arifes  from  a  portion  of  phofphorus,  from  which  this 
acid  is  difficultly  cleared  :  and  vapours  likewife  rife.  The  li- 
quor becomes  turbid,  afiumes  a  milky  appearance,  and  a  pally 
confiftence  ;  and  if  the  matter  be  put  into  a  crucible,  on  hot 
coals,  it  boils  confiderably.  The  vapour  which  ilTues  renders 
the  flame  green  ;  and  the  mafs  at  lalt  becomes  converted  into  a 
white  traniparent  glafs  infoluble  in  water. 

The  phofphorick  acid  has  no  action  on  quartz. 

It  diflblves  clay  with  ebullition. 

.  It  diffolves  barytes  ;  and  unites  to  clay  with  fmgular  facility, 
with  which  it  forms  a  fait  of  fparing  folubility.  The  folution, 
when  v/ell  charged,  lets  fall,  at  the  end  of  four-and-twenty 
hours,  cryflals  in  fmall  thin  flattened  needles,  fevera!  lines  lonp:, 
and  obliquely  truncated  at  each  end.      The  phofphoiick  acid 


FhoJ^horick  Salts*     Animal  Suhjiances*  583 

precipitates  lime  from  lime  water,  and  forms  a  true  phofphate  of 
lime  very  fimilar  to  the  bafis  of  bones,  and  decompofable  by  the 
mineral  acids  like  that  fubltance. 

The  phofphorick  acid,  faturated  with  potafli,  forms  a  very  fo- 
luble  fait,  which  aifordstetrahedral  cryltals  terminating  in  te- 
trahedral  pyramids.  This  phofphate  is  acid,  fwells  up  on  hot 
coals,  and  is  difficult  of  fufion.     Lime  water  decompofes  it. 

Soda,  combined  with  the  phofphorick  acid,  affords  a  fait  of  a 
tafte  refembling  that  of  the  muriate  of  foda.  This  phofphate 
does  not  cryftallize,  but  becomes  converted  into  a  gummy  and 
deliquefcent  mafs  by  evaporation.  Mr.  Sage  affirms  that  phof- 
phate of  Soda  prepared  with  the  acid  of  the  flow  combuftion, 
forms  a  fait  fufceptible  of  cryftallization. 

Dr.  George  Pearfon  has  combined  the  phofphorick  acid  obtain- 
ed by  nitrick  acid,  with  foda,  and  obtained  a  neutral  fait  ia 
rhomboids. 

This  fait,  though  faturated,  turns  fyrup  of  violets  green,  ef- 
florefces  in  the  air,  and  has  a  faline  tafte  refembling  that  of 
common  fait.  It  purges  in  the  dofe  from  fix  to  eight  drams, 
without  producing  either  naufea  or  griping,  and  has  not  a  difa- 
greeable  tafte. 

The  phofphorick  acid  afts  only  on  a  fmall  number  of  metal- 
lick  fubftances.  On  this  fubje£l  the  works  of  MeiT.  Margraaf, 
and  De  Morveau  may  be  confulted. 

The  phofphorick  acid  has  a  very  evident  acftion  on  oils.  Mi»«- 
cd  with  an  equal  portion  of  olive  oil,  it  acquires  a  fawn  colour 
by  mere  agitation,  which  fubfifts  even  after  the  feparation. 
This  (hade  increafes  if  the  two  fluids  be  digefted  together  ;  the 
acid  becomes  thick  ;  and  the  oil  which  floats  above  becomes 
black  and  coaly,  and  emits  a  ftrong  fmell. 


CHAPTER   X. 

Concerning  certain  Subftances  obtained  from  Animals  for  the  ufe  of  Med* 
icine  and  the  Arts. 

THERE  is  not  perhaps  any  animal  produ<S^  whofe  virtues 
have  not  been  celebrated  by  fomeof  the  phyficians  j  and  ther^ 
are  few  animals  which  have  not  at  fomc  time  or  other  been 
mentioned  as  contributing  to  the  advantage  of  medicine.  Time 
however  has  happily  condemned  to  oblivion  thofe  productions 
which  ought  never  to  have  poirelTed  celebrity  ;  and  we  (hall  ac- 
cordingly on  the  prefent  occafion,  attend  only  to  fuch  as  experi- 
ence has  (hown  to  poirefs  che  virtues  and  powers  attributed  t© 
them. 


584  ^^p^ 


'-oreum. 


We  (hall  not  therefore  treat  of  the  lungs  of  the  fox,  the' liver 
of  the  wolf,  the  feet  of  the  elk,  thejaws  of  the  carp,  the  neils 
of  the  fwallow,  the  powder  of  the  toad,  the  dung  of  the  pea- 
cock; the  heart  of  the  viper,  the  fat  of  the  badger,  nor  even  that 
of  the  hanged  malefadlor. 

Various  quadrupeds,  cetaceous  animals,  birds,  and  fifhes,  af- 
ford produt^s  in  which  chemical  and  medical  experience  has  af- 
certaincd  very  evident  virtues. 

ARTICLE     r. 

Concerning  the  Prodafls  afforded  by  Quadrupeds. 

Under  this  article  we  (hall  treat  of  the  products  mort  in  ufe 
which  are  extradled  from  quadrupeds.  Thefe  are  caftoreum, 
mufk,  and  hartfhorn. 

1.  The  name  of  Caftorcum  is  given  to  an  un<fl:uous  fluid  con- 
tained in  two  pouches  fituated  in  the  inguinal  region  of  the 
male  or  female  caftor.  An  accurate  defcription  of  it  may  be 
feen  in  the  Encyclopedie.  This  very  odorant  fubftance  is  foft, 
and  nearly  fluid  when  recently  extraf^ed  from  the  animal  ;  but 
it  dries  in  the  courfe  of  time.  It  has  an  acrid  bitter  and  naufe- 
ous  tafte  j  and  its  fmell  is  ftrong,  aromatick,  and  even  {link- 
ing. 

Alcohol  diflblves  a  refm  which  colours  it  ;  water  extrafls  an 
abundant  principle.  By  evaporation  of  the  water  a  fait  is  ob- 
tained, the  nature  of  which  is  little  knovvn.  Caltoreum  afl?brds 
by  diftillation  a  fmall   quantity  of  volatile  oil,  ammoniack,  &c. 

The  ufes  of  caftor  in  the  economy  of  the  animal  are  unknown. 
The  ancients  had  the  credulity  to  believe  that  the  creature  itfelf 
took  it  when  its  ftomach  was  weak. 

It  is  ufed  in  medicine  as  a  powerful  antifpafmodickjin  the  dofe 
of  a  few  grains  in  fubftance  ;  and  it  enters  as  a  component  part 
intobolouies,  extracts,  &c.  It  is  advanta^reoufly  joined  with  o- 
pium  ;  and  its  fpiritous  tin£lure  is  alfo  prefcribed  in  fuitable  li- 
quids, in  a  dofe  from  twenry-four  to  thirty-fix  drops. 

We  fee  clearly  from  the  little  chemical  information  we  pof- 
fefs  refpe(Sting  this  fubftance,  that  it  is  a  refin  joined  with  a  mu- 
cilage, and  a  fait  which  facilitates  the  union  of  its  principles. 

2.  The  name  of  mulk  is  given  to  a  perfume  obtained  from 
various  animals.  In  1726  an  animal  was  received,  under  the 
name  of  the  Muflc  Animal,  in  the  Royaf  Menagerie,  which  came 
from  Africa  and  refembled  the  civit.  Mr  Perrault  has  left  a 
defcription  of  it.  It  was  fupported  fix  years  upon  ravv  flefh. 
M.  Dc  la  Peyronnie  gave  a  very  good  defcription  of  it  to  the 
Academy  of  Sciences  for  the  year  1 73 1. 


The  Mujk  Animal.      Hartjhortt.  58^; 

The  organ  which  contained  the  mulk  was  fituated  near  the 
genital  parts  (it  was  a  female.)  At  the  aperture  of  the  bag 
which  contained  the  muik  the  fmell  was  fo  ftrong,  that  M,  De 
la  Peyronnie  could  not  inf..e6\  it  without  inccnvcn'tnce.  Tliis 
liquor  is  prepared  by  two  glands,  which  tranfmit  it  into  the 
common  refervoir  through  a  number  of  fmali  perforations. 

The  othei  animal  which  affords  mufk  in  the  Ea(t,  is  of  the 
clafs  of  fquirrels.  It  is  very  common  in  Chinefe  Tartary.  It 
carries  the  muflc  in  a  bag  beneath  the  navel.  This  bag  project- 
ing outwards  of  the  (Ize  of  a  p\illet's  ^ggy  is  formed  of  a  mem- 
braneous and  mufcular  fubftance,  provided  with  a  fphinfter. 
Many  glands  are  obfervable  within,  which  feparate  the  humour. 
As  foon  as  the  beaft  is  killed,  this  bladder  is  cut  off  and  tied  up  : 
but  its  contents  are  adulterated  uith  the  tellicles,  the  blood,  and 
orher  offals  of  the  animal  ;  for  each  creature  affords  no  more 
than  three  or  four  gros.  Muflc  mud  be  chofen  foft,  unctuous, 
and  odorant ;  and  ought  to  be  confumed  totally  upon  hot  coals. 
The  mulk  of  Tonquin,  which  is  moft  efteemed,  is  contained  in 
bags  covered  with  brown  hair  ♦,  but  that  of  Bengal  is  covered 
with  white  hair. 

Muik  contains  nearly  the  fame  principles  as  cafloreum.  The 
fmell  of  pure  and  unmixed  mulk  is  too  ftrong  and  oppreffive. 
It  is  rendered  mild  by  mixture  with  other  fubltances.  It  is  lit- 
tle ufed  in  medicine  ;  is  a  powerful  antifpafmodick  in  fome  ca- 
fes ;  but  ought  to  be  adminiftered  with  caution,  becaufe  it  often 
excites  nervous  iiffeClions  inftead  of  calming  them. 

The  fmcli  of  mufk  predominates  in  certain  animals.  M.  De 
hi  Peyronnie  knew  a  man  from  whofe  left  arm-pit  there  was 
emitted  fo  ftrong  a  fmell  of  mufk  during  the  fummer,  that  he 
was  obliged  to  weaken  it  to  avoid  inconvenience. 

3.  Hartihorn  affords  feveral  products  which  are  much  em- 
ployed in  medicine.  The  preference  is  given  to  this  horn  be- 
caufe it  contains  lefs  earthy  fait  than  bones  ;  but  all  kinds  of 
horn  may  be  ufed  indifcriminarely. 

Hartfliorn  was  formerly  calcined  with  the  greateil  care,  and 
ufed  as  a  remedy  againft  alvine  fluxes. 

The  producfbs  of  hartfhorn  which  are  moflly  ufed  at  prefent, 
are  thofe  obtained  by  diftillation.  An  alkaline  phlegm  is  firit 
obtained,  which  is  called  the  Volatile  Spirit  of  Hartfliurn.  Next 
comes  over  a  reddifli  oil^  more  or  lefs  empyreun^atlck  ;  and  a 
very  great  quantity  of  carbonate  of  ammoniack,  f^.:)iled  and  col- 
oured by  the  empyreumatick  oil.  The  oil  which  colours  the 
fait  may  be  difengaged  by  means  of  fpirit  of  wine,  which  dif- 
folves  It.  The  coaly  refidue  contains  natrum,  fulphate,  and 
4-C 


586  Animal  (yd  of  D'lpple,     Spennacefi. 

and  pKofphate  of  lime,  from  which  phofphorus  may  be  obtained 
by  the   proceiTes  already  defcribed. 

The  fpirit  and  the  fait  obtained  from  hartfliorn  are  ufed  in 
medicine  as  good  antifpafmodicks. 

The  oil  duly  rectified  forms  the  animal  oil  of  Dippel.  As 
the  higheft  virtues  have  been  attributed  to  this  fub (lance,  a 
thoufand  methods  have  been  attempted  to  purify  it.  For  a 
long  time  it  was  ufual  to  re6lify  it  a  great  number  of  times,  in 
order  to  have  it  white  and  fluid.  But  Meflrs.  Model  and  Baume 
have  adviled  taking  only  the  firft  portion  which  comes  over,  be- 
caufe  this  is  the  mod  attenuated,- and  the  whiteft.  Rouelle  ad- 
vifes  diftillation  with  water  ;  and  as  the  moft  volatile  part  only 
arifes  with  the  heat  of  boiling  water,  there  is  a  certainty  of  hav- 
ing it  very  fine  by  this  means.  For  my  part,  I  diftil  the  em- 
pyreumatick  oil  with  the  earth  of  Murviel,  which  retains  all  the 
colouring  part  j  and  by  this  means  I  have  it  at  once  white  and 
attenuated. 

This  is  odorant,  and  has  all  the  properties  of  the  volatile  oils  : 
but  it  turns  fyrup  of  violets  green,  as  Mr.  Parmentier  has  ob- 
ferved  5  which  proves  that  it  retains  a  fmall  quantity  of  volatile 
alkali.  This  oil  is  ufed  in  dofes  of  a  few  drops  in  nervous 
atFeclions,  epilepfy,  &.c.  It  is  ufed  externally,  by  rubbing  it  on 
the  fkin,  as  a  fedative,  and  to  remove  obftruclions  ;  but  the  great 
virtues  formerly  attributed  to  it  are  not  much  credited  at  pref- 
ent. 

ARTICLE     11. 

Concerning  certain  Products  afforded  byFiflies. 

The  oil  of  fifli,  and  fpermaceti,  are  the  moft  ufed  among  the 
produfls  obtained  from  lidies. 

Spermaceti  is  a  concrete  oil  extracted  from  the  cacholot. 
The  name  of  Sperma-ceti  is  very  improper.  Thefe  animals 
are  of  a  prodigious  fize,  and  afford  large  quantities  of  this  mat- 
ter. Plomet  relates  that  in  1688  a  Spaniili  fhip  took  a  whale 
whofe  head  afforded  twenty-four  barrels  of  brains,  and  the  bo- 
dy ninery  fix  barrels  of  fat.  This  fpermaceti  is  always  mixed 
with  a  certain  quantity  of  inconcrefcible  oil,  which  is  carefully 
removed. 

Spermaceti  burns  with  a  very  white  flame.  It  is  made  into 
candles  at  Bayonne  and  at  St.  Jean  de  Luz.  Thefe  candles  arc 
of  a  white  iliining  colour,  become  yellow  in  procefs  of  time, 
but  not  fo  foon  as  wax  and  the  denfe  oils. 

If  it  be  diftilled  on  a  naked  fire,  it  does  not  afford  an  acid 
phlegm,  but  rifes  totally,  at  the  fame  time  that  it  affumes  a  red- 
difh  tinge.  Several  repeated  diftillations  deprive  it  of  its  natur- 
al confillcnce. 


Component  Parts  of  Eggs.  587 

The  fulphurick  acid  dlflblves  it  ;  and  this  folution  is  pre- 
cipitated like  the  oil  of  camphor.  The  nitrick  and  muriatick 
acids  have  no  adion  upon  it. 

Cauftick  alkali  diiTolves  fpermaceti,  and  forms  a  foap  which 
gradually  acquires  folidity. 

Alcohol  diflblves  fpermaceti,  by  the  afliftance  of  heat,  but  lets 
it  fall  as  it  cools.     Ether  likewife  diflblves  it. 

The  fixed  and  volatile  oils  diflblve  it  by  the  afliftance  of  heat. 

This  fubltance  vi^as  formerly  much  ufcd.  It  was  given  ^«  an 
emollient,  and  fuftening  remedy ;  but  at  prefent  it  is  almofl: 
forfaken,  and  not  without  caufe  •,  for  it  is  heavy,  infipid,  and 
naufeous. 

The  egg,  the  fcales,  and  the  black  fluid  of  the  cuttle  fifli,  are 
ftill  ufed  in  medicine.  The  eggs  deterge  the  kidneys  and  excite 
urine  and  the  courfes.  The  fcales  and  bones  of  the  cuttle-fifh 
are  applied  to  nearly  the  fame  ufes  :  they  are  likewife  ufed  as 
an  altringent ;  and  enter  into  dentifrice  powders,  collyria,  &c. 
The  gbldfmiths  likewife  ufe  them  to  make  their  moulds  for  cafl;- 
ing  fpoons,  forks,  toys,  &c.  becaufe  its  fpongy  part  eafily  re- 
ceives the  imprefllon  of  metals.  The  black  humour  of  the  cut- 
tle-fifii,  which  is  found  in  a  bag  near  the  ccecum,  and  of  uhich 
Mr.  Le  Cat  has  given  a  defcripiion,  may  be  ufed  infl:ead  of  ink. 
W^  read  in  the  Satires  of  Perfius  that  the  Romans  ufed  it  as  an 
ink  ;  and  Cicero  calls  it  Atramentum.  It  feems  that  the  Chi- 
nefe  ufe  it  as  the  bafis  of  their  famous  ink.  **  Sepia  pifcis  efl: 
qui  habet  fuccum  nigerrimum,inftar  atramenti,  quern  Chinenfes 
cum  brodio  orizse,  vel  alterius  leguminis,  infpifl^ant  et  formant, 
et  in  univerfum  orbem  tranfmittunt,  fub  nomine  Atramenti 
Chinenfis"  (Pauli  Hermani  Cynofura,  t.  i.  p.  17,  par.  2.)  Pliny 
was  of  opinion  that  the  black  humour  of  the  cuttle-fifh  was  its 
blood.  Rondelet  has  proved  that  it  is  the  bile.  This  is  the  flu- 
id the  cuttle-fifli  difgorges  when  in  danger  :  a  very  fmall  quan- 
tity is  fuflicient  to  blacken  a  large  quantity  of  water. 

Calcined  oyiler  fhells  are  likewife  ufed  in  medicine  as  an  ab- 
forbent. 

The  oil  extraded  from  fifli  is  of  the  greatefl:  ufe  in  the   arts. 

ARTICLE  III. 

Concerning  certain  Produfcs  afforded  by  Birds. 
Moft:  of  the  birds  are  ufed  at  our  tables  as  a  delicate  food, but 
few  affbrd  any  medical  products.  The  eagle  ftones,  to  which 
fo  much  virtue  had  been  attributed  for  facilitating  labours,  the 
plafters  of  fwallows  nen:s,  and  other  fimilar  fubltances,  have 
all  fallen  into  negledl,  as  the  natural  coiifequence  of  the  obfer- 
vation  of  matter  of  fact  being  fubilituted  in  the  place  of  credu- 


588  Analyfu  of  Cantharides. 

lity  and  fuperflltion.  The  analyfis  of  eggs  begins  to  be  kno^vn. 
They  confill:  of  four  parts  :  an  olleous  covering,  called  the  iii'iii  j 
a  membrane  which  covers  the  conftituent  parts  of  the  egg  \ 
the  white  ;  and  the  yolk,  which  occupies  the  centre. 

The  (hell,  like  bones,  contains  a  gelatinous  principle,  and 
the  phofphate  of  lime. 

The  white  is  of  the  fame  nature  as  the  ferum  of  blood.  It 
renders  fyrup  of  violets  green,  and  contains  uncombined  chalk  ; 
-  heat  coagulates  it  •,  by  diftillation  it  affords  a  phlegm  which  ea- 
fily  putrefies  ;  it  becomes  dry  like  horn  ;  and  carbonate  of  am- 
moniack,  and  empyreumatick  oil,  come  over.  A  coal  remains 
in  the  retort,  which  affords  foda,  and  phofphate  of  hme.  M. 
Deyeux  has  alfo  obtained  fulphur  by  fublimation. 

Acids  and  alcohol  coagulate  it. 

If  it  be  expofed  to  the  air  in  thin  leaves,  it  dries,  and  becomes 
confiftent  ;  and  it  is  on  tliis  property  that  the  cultom  is  found- 
ed of  paffmg  the  white  of  ^gg  over  the  furface  of  paintings,  to 
give  them  that  brightnefs  which  is  produced  by  varnilli,  and  al- 
fo to  defend  them  from  the  air.  The  drying  may  be  haftened 
by  quick-lime  \  and  this  mixture  affords  a  lute  of  the  greatefl 
tenacity. 

The  yolk  of  eggs  likewife  contains  a  lymphatlck  fubftance, 
mixed  with  a  certain  quantity  of  mild  oil,  which  on  account  of 
this  mixture  is  foiubie  in  water.  It  is  this  animal  emulfion 
which  is  known  in  France  by  the  name  of  hit  de poulle.  Yolk 
of  egg  expofed  to  the  fire  affumes  a  confiftence  lefs  hard  than 
the  white.  If  it  be  bruifed,  it  appears  to  have  fcarcely  any  con- 
fiftence ;  and  if  it  be  fubjcdted  to  the  prefs,  it  gives  out  the  oil 
it  contains.  This  oil  is  very  emollient,  and  is  ufed  externally  as 
a  liniment.  There  is  the  greateft  analogy  between  the  egg  of 
animals  and  the  feeds  of  vegetables  ;  fince  both  contain  an  oil 
rendered  foluble  in  water  by  the  admixture  of  a  glutinous  fub- 
ftance. 

The  yolk  of  egg  renders  oils  and  refins  foluble  ;  and  this  fub- 
ftance is  accordingly  much  ufed  for  that  purpofe. 

Calcined  egg  (hells  is  an  abforbent. 

White  of  egg  is  fuccefsfully  ufed  to  clarify  vegetable  juices, 
whey,  liquors,  &c.  It  coagulates  by  heat  5  and  then  rifes  to 
the  furface  of  thefe  fluids,  carrying  with  it  all  the  impurities 
they  contain. 

ARTICLE    IV. 

Concerning  certain   Produces  afforded  by  Infecls. 
Millepedes,  cantharides,  kermes,  cochenille,  and  lac,  are    \\\t 
only  fubftances  we  (hall  here  treat  of,  becaufe  thefe  are  not  on- 


Analyjti  of  Caniharldes,  ^8^ 

Jy  the  moft  ufed,  but  are  likewife  the  beft  known  among  the 
produds  of  infe^ls. 

I.  Cantharides. — The  cantharides  are  fmall  infecls  with 
greenilb  wings  They  are  very  common  In  hot  countries  ;  and 
are  found  on  the  leaves  of  the  aih,  the  roi'e  tree,  the  poplar,  the 
walnut  tree,  the  privet,  &c. 

Cantharides  in  powder,  applied  to  the  epidermis,  caufe  bUft- 
ers,  excite  heat  in  the  urine,  ftrangury,  third  and  fever.  They 
produce  the  fame  effedl:  taken  internally  in  a  fmall  dofe.  We 
read  in  Pare  that  a  courtezan,  having  prefented  a  ragout  pow- 
dered with  cantharides  to  a  young  man  who  fupped  with  her, 
this  unfortunate  perfon  was  attacked  with  a  priapifm,  and  lofs 
of  blood  by  the  anus,  of  which  he  died.  Boyle  affirms  that 
pains  at  the  neck  of  the  bladder  have  been  produced  by  the 
handling  of  cantharides. 

Wv^  are  indebted  to  Mr.  Thouvenel  for  fome  information  re- 
fpec^ting  the  conltituent  principles  of  thefe  inlefts.  Water  ex- 
tra£ls  a  very  abundant  principle,  which  colours  it  of  a  reddifh 
yellow,  and  alfo  a  yellowifli  oily  principle.  Ether  takes  up  a 
green  very  acrid  oil,  in  which  the  virtue  of  the  cantharides  moft 
eminently  refides.     So  that  an  ounce  of  cantharides  affords — 


Reddifh  yellow  bitter  extra6l 

Yellow  oily  matter 

Green  oily  fubftance,  analogous  to  wax 

Parenchyma,  infoluble  in  water  and  alcohol 


To  form  a  tintlure  which  unites  all  the  properties  of  can- 
tharides, a  mixture  muft  be  made  of  equal  parts  of  water  and  of 
alcohol,  and  the  infects  digefted  in  ir.  If  this  tincSlure  be  dif- 
tilled,  the  Ipirit  which  comes  over  retains  the  fmell  of  canthar- 
ides. 

If  fpirit  of  wine  alone  be  ufed.  It  takes  up  merely  the  cauflick 
part  ;  hence  it  appears  that  the  virtue  of  thefe  infedls  may  be 
increafed  or  diminiftied  according  to  the  exigence  of  the 
cafe. 

The  tIncSlure  of  cantharides  may  be  ufed  with  fuccefs  exter- 
nally, in  the  dofe  of  two  gros,  four  gros,  one  or  even  two  ounc- 
es, in  rhcumatick  pains,  fciatica,  wandering  gout,  &c.  It  heats 
the  parts  ;  accelerates  the  circulation  ;  excites  evacuations  by 
perfpiration,  urine  or  ftool,  according  to  the  parts  to  which  it  is 
applied. 


ros. 

grains. 

3 

o 

o 

12 

o 

6o 

4 

o 

8 

o 

S^o  ProduBion  of  Cochinelle. 

Mr.  Thouvenel  tried  upon  hlmfelf  the  efFe£l  of  the  green 
waxy  matter.  When  applied  on  the  (kin  in  the  dofe  of  nine 
grains,  it  raifed  a  bhfter  full  of  ferofity. 

2.  The  wood  lice,  millepedes,  afelli,  porcelli. — ^This  infeft  is 
ufually  found  in  moiil  places,  under  (tones,  or  beneath  the  bark 
of  old  trees.  It  avoids  the  light,  and  ende-ivours  to  conceal  it- 
felf  when  difcovered.  When  it  is  touched,  it  rolls  up  in  the 
form  of  a  globe.  This  infecT:  is  ufed  in  medicine  as  an  incifive, 
aperitive  and  alterative  remedy.  It  is  prefcribed  either  pounded 
alive  and  put  into  a  proper  liquid,  or  dried  and  pulverized,  in 
which  laft  form  they  enter  into  extra£ls,  pills,  &c.  The  mille- 
pedes are  given  m  the  dofe  of  fourteen,  fifteen,  and  twenty  grains 
or  more,  according  to  the  exigency  of  the  cafe.  Mr.  Thouve- 
nel has  given  us  foirie  information  concerning  the  conftituent 
principles  of  thefe  infetls.  He  obtained  by  diftillation  an  infip- 
id  or  alkaline  phlegm  ;  the  refidue  afforded  an  extra6live  mat- 
ter, an  oily  or  waxy  fubftance  foluble  in  fpirit  of  wine  only,  and 
marine  fait  with  an  earthy  and  an  alkaline  bafe. 

3.  Cochenille. — Cochenille  is  a  fubftance  ufed  in  dying  fcar- 
let  and  purple.  It  is  met  with  in  commerce  in  the  form  of 
fmall  grains  of  a  fingular  figure,  moftly  convex,  with  little 
grooves  on  one  fide,  and  concave  on  the  other.  The  colour  of 
good  cochenille  is  grey  mixed  with  reddifh  and  white.  It  is  at 
prefent  well  determined  that  it  is  an  infect.  Simple  infpedlion 
with  a  magnifier  fufhciently  proves  this  :  and  the  wings  and 
feet  of  this  infe£l  may  be  developed  by  expofmg  it  to  the  vapour 
of  boiling  water,  or  by  digefting  it  with  vinegar.  The  coche- 
nille is  collected  in  Mexico,  upon  plants  to  which  the  name  of 
Indian  Fig,  Raquette  Nopal,  are  given.  Thefe  plants  bear  fruits 
which  refemble  our  figs  ;  tinge  the  urine  of  thofe  who  eat  them 
and  probably  communicate  to  the  cochenille  the  property  which 
makes  it  ufeful  to  the  dyer.  The  Indians  of  Mexico  cultivate 
the  nopal  near  their  habitations,  and  fow  as  it  were  the  infect 
which  affords  the  cochenille.  They  make  fmall  nefls  of  mofs  or 
fine  herbs,  put  twelve  or  fourteen  cochenilles  into  each  neft, 
place  three  or  four  of  thefe  nefts  on  each  leaf  of  the  nopal,  ii\\6. 
faflen  them  there  by  the  prickles  of  the  plant  ;  in  the  courfe  of 
a  few  days,  thoufands  of  fmall  infers  iflue  out  and  fix  them- 
felves  upon  the  parts  of  the  leaf  which  are  bed  (lieUered,  and  af- 
ford the  mod  nourifh'aient.  The  cochenilles  are  coliecled  fev- 
eral  times  in  the  courfe  of  the  year  ;  and  are  deprived  of  life  by 
fcalding  them,  or  by  putting  them  into  an  oven  ;  after  which 
they  are  dried  in  the  fun.  Two  kinds  of  cochenille  are  di  tm- 
guiihed  :  the  one  which  is  produced  without  culture,  and  is 
called  Svlveftre  \  and  the  other  cultivated,  which  is  called  Mef- 


Preparations  of  Kermes,  591 

tcque.  Thislafl  is  preferred.  It  has  been  calculated  in  the  year 
1736,  that  eight  hundred  and  eighty  thoufand  pounds  weight 
ofcochenille  was  annually  imported  into  Europe.  Mr.  Ellis 
has  communicated  a  very  good  defcription  of  the  cochenille  to 
the  Rnyal  Society  of   London. 

This  I'ubltance  is  more  efpecially  ufed  in  dying  :  its  colour 
takes  readily  upon  wool ;  and  the  mod  fuitable  mordant  is  the 
muriate  of  tin.  Mr.  Macquer  has  difcovered  a  method  of  fix- 
ing this  colour  uponfiik,  by  impregnating  the filk  with  a  folution 
of  tin  before  it  is  plunged  into  the  bath  of  cochenille  ;  inftead 
of  mixing  a  folution  in  the  baths,  as  is  done  for  woollens. 

4.  Kerrnes. — Kermcs  is  a  kind  of  excrefcence,  of  the  fize  of 
a  juniper  berry,  which  is  greatly  employed  in  medicine  and 
the  arts. 

The  tree  which  bears  it  is  known  by  the  name  of  Quercus  I- 
lex.  It  grows  in  hot  countries  ;  in  Spain,  Languedoc,  Prov- 
ence, &c.  The  female  of  the  coccus  fixes  itfelf  on  the  plant  ; 
it  has  no  wings,  but  the  male  has.  When  flie  is  fecundated, 
ihe  becomes  large  by  the  developement  of  her  eggs  ;  (lie  perifh- 
es,  and  the  eggs  are  hatched.  It  is  colle6led  before  the  devel- 
CDement  of  the  eggs  ;  for  which  purpofe,  the  morning  is  taken 
before  the  heat  has  acled  upon  the  e^gs.  The  grains  are  col- 
lefted  and  dried,  to  develope  the  red  colour  ;  they  are  then  fift- 
ed,  tofeparate  the  powder;  and  laftly  they  are  fprinkled  with 
good  vinegar,  to  kill  the  infedl,  which  would  othcrwife  come 
forth  in  a  (hort  time. 

Kerrnes  is  much  ufed  in  the  arts  :  it  affords  a  good  red,  but 
lefs  brilliant  than  that  of  the  cochenille. 

A  very  celebrated  fyrup  of  kermes  is  made,  by  mixing  three 
parts  of  fugar  with  one  of  the  grains  of  kermes  pulverized.  The 
mixture  is  kept  for  a  day  in  a  cool  place  :  the  fugar  during  this 
time  unites  with  the  juice  of  the  kermes  ,  and  forms  with  it  a 
liquor  which,  when  drawn  off  by  expreffion,  has  the  confidence 
of  fyrup.  The  celebrated  confedio  alkermes  is  made  with  this 
fyrup. 

The  grains  of  kermes  given  in  fubftance,  from  half  a  fcruple 
to  a  gros  or  dram,  are  celebrated  for  preventing  abortion. 

The  grain  and  the  fyrup  of  kermes  are  an  excellent  ftom- 
achick. 

5.  Lac,  or  gum  lac. — This  is  a  kind  of  wax,  collected  by  red 
winged  ants  from  tlowers  in  the  Eafl-Indies,  which  they  tranf- 
porc  to  the  fmall  branches  of  the  tree  where  they  make  their 
ncfts.  The  nefls  are  full  of  fmall  cells,  in  which  a  red  grain 
is  found  when  the  mafs  is  broken.  This  fmall  grain  is,  to  all 
appearance,  the  egg  from  which  the  flying  ant  derives  its  or- 
igin. 


59^  -^^^^  rf  5//^  Worms, 

Mr.  GeofFroy  has  proved,  in  a  Memoir  infcrted  among  thofe 
of  the  Academy  for  the  year  17 14,  that  this  muft  have  been  a 
kind  of  comb,  approaching  to  the  honeycomb  of  bees,  the  cells 
of  which  are  formed  of  a  fubftance  analogous  to  v/ax.* 

The  colouring  part  of  lac  may  be  taken  up  by  water,  which, 
when  evaporated,  leaves  the  colouring  principle  difcngaged.  It 
is  the  fine  lake  ufed  for  dying.  Lake  is  imitated  by  extracffcing 
the  colouring  principle  of  certain  plants  by  well  known  proc- 
cfles. 

CHAPTER    XL 
Concerning  fome  other  Acids  extracted  from  the  Animal  Kingdom. 

INDEPENDENT  of  the  acids  afforded  by  the  various  parts 
of  the  human  body,  which  have  been  feparately  examined  by  us 
we  find  acids  in  mod  infe£ls.  Lifter  points  out  one  which  may 
be  extracted  from  millepedes  (Collect.  Acad.  torn.  ii.  p.  303). 
Mr.  Bonnet  has  obferved  that  the  fluid  eje61:ed  by  the  great  fork- 
ed tail  caterpillar  of  the  willow,  was  a  true  acid,  and  even  very 
adlive  (Savans  Etrangers,  tom.  ii.  p.  276):  Bergmann  compares 
it  to  the  moll  concentrated  vinegar.  The  abbe  Boi flier  de  Sau- 
vageshas  remarked,  that  in  that  illnefs  of  the  filk  worm,  which 
is  called  mufcardin,  the  humour  of  the  worm  is  acid.  Mr. 
ChauflTier  of  Dijon  obtained  an  acid  from  grafs-hoppers,  from 
the  May-bug,  from  the  hmpyris,  and  feveral  other  infects,  by 
digefting  them  in  alcohol.  The  fame  chemift  has  made  an  in- 
terefting  courfe  of  experiments  on  the  acid  of  the  filk  worm. 
He  gives  two  methods  of  extrading  it.  The  firft  confifts  in 
bruifing  the  chryfalides,  and  ftraining  them  through  a  cloth.  The 
fluid  which  paiTes  is  ftrongly  acid  ;  but  the  acid  is  weakened  by 
various  foreign  fubfl:ances,  of  which  it  may  be  cleared  by  digef- 
tion  in  fpirit  of  wine.  The  fluid  which  pafles  the  filtre  after 
this  digeftion,  is  of  a  fine  orange  colour.  More  fpirit  of  wine 
is  to  be  poured  upon  it.  At  every  addition  of  fpirit  a  light 
whitilh  precipitate  is  formed  ;  and  the  additions  of  fpirit  are  to 
be  continued  until  no  more  precipitate  appears. 

Initead  of  bruifing  the  chryfalides  they  may  be  infufed  in  fpirit 
of  wine,  whicli  difiblves  all  the  acid  ;  and  as  this  acid  is  lefs  vol- 
atile than  the  fpirit,  thislaft  may  be  evaporated,  and  the  refidue 

*  For  a  defcription  and  drawing  of  the  infedt  which  affords  the  lac, 
confult  Keir  in  the  Philof.  Tranf.  vol.  Ixxi.  p.  374  ;  alfo  Saunders,  in 
the  fame  work,  vol.  Ixxix  for  the  method  of  purifying  the  lac  ;  or  a  fliort 
abridgment  of  both,,  in  Nicholfon's  Firft  Principles  of  Cheniiftry,  p. 
490.    T. 


•  t 


Acid  of  Ants,  ^ "       £02 

filtered.  By  thefe  precautions  the  aeid  may  be  cleared  of  its 
fpirit  of  wine,  and  of  the  mucous  matter  which  was  diflblved, 
but  remains  on  the  filtre. 

Mr.  Chauffier  has  proved  that  tiiis  acid  exifts  in  all  the  dates 
of  the  filk  worm,  even  in  the  eggs  ;  but  that  in  the  egg  and  in 
the  worm  it  does  not  exift  in  a  difengaged  ftate,  but  combined 
with  a  gummy  glutinous  fubftance. 

The  acid  of  infects  which  is  beft  known,  and  upon  which 
tnoil  has  been  wtitten,  is  the  acid  of  ants,  or  the  formick  acid. 
This  acid  is  fo  far  in  a  difengaged  ftate,  that  the  tranfpiration  of 
thefe  animals,  and  their  fimple  contact  without  any  alteration, 
proves  its  exigence. 

The  authors  of  the  fifteenth  century  had  obferved,  that  the 
flower  of  chickory  thrown  into  an  ant  hill  becomes  as  red  as 
blood. — ^See  Langham,  Hieronimus  Tragus,  John  Bauhin. 

Samuel  Filher  is  the  firft  who  difcovered  the  acid  of  ants,  in 
a  courfe  of  experiments  for  the  analyfis  of  animal  fubftances  by 
t!i(lillation.  He  even  tried  its  aOion  on  lead  and  iron  ;  and 
communicated  his  obfervations  to  J.  Vray,  who  inferted  them  in 
the  Philofophical  Tranfa(fiions  in  the  year  1670.  But  it  was 
the  celebrated  Margraaf  who  more  particularly  examined  the 
properties  of  this  acid  in  1749.  He  combined  it  with  many 
fubftances,  and  concluded  that  it  greatly  refembled  the  acetous 
acid.  In  1777  this  fubjefl  was  again  refumed  by  Meflrs.  Ar- 
vidflbn  and  Oerhn  ;  and  treated  in  a  manner  which  leaves  lit- 
tle to  be  defired,  in  their  differtation  publiftied  at  Leipfic. 

The  ant  which  affords  the  greateft  quantity  of  acid,  is  the 
large  red  ant  which  is  found  in  dry  and  elevated  places. 

The  months  of  June  and  July  are  moft  favourable  for  the  ex- 
traction of  this  acid  i  they  are  then  fo  penetrated  with  it,  that 
their  fimple  pafling  over  blue  paper  is  fufficient  to  turn  it  red. 

Two  methods  may  be  ufed  to  obtain  this  acid  :  dift illation, 
and  lixiviation. 

To  extract  the  acid  by  diftillation,  the  ants  are  firft  dried  by 
a  gentle  heat,  and  put  into  a  retort,  to  which  a  receiver  is  adap- 
ted, and  fhe  fire  is  raifed  by  degrees.  When  all  the  acid  is 
come  over,  it  is  found  in  the  receiver  mixed  with  a  fmall  quan- 
tity of  empyreumatick  oil,  which  floats  upon  it,  and  may  be  fep- 
rated  by  a  funnel.  Meflrs.  Arvidffbn  and  Oerhn  obtained,  in  this 
manner,  from  each  pound  of  ants  feven  ounces  and  a  half  of  an 
acid  whofe  fpecifick  gravity,  at  the  temperature  of  fifteen  de- 
grees, was  to  that  of  water,  as  1-0075  to  i.oooo 

In  the  procefs  of  lixiviation,  the  ants  are  waftied  in  cold  wa- 
ter ;   and  boiling  water  is  afterwards  poured  over  them,  which  is 
filtered  when  cold.     More  boiling  water  is  poured  over  the  ret- 
4...D 


5^4  ^^/V  of  AntSm 

idue,  and  likewife  filtered  when  cold.  By  tins  meanff  one  pound 
of  ants  affords  a  pint  of  acid  as  ftrong  as  vinegar,  and  of  a  great- 
er fpecifick  gravity.  MeiTrs.  Arvidflbn  and  Oerhn  are  of  opin- 
ion that  this  acid  might  be  fubftituted  inftead  of  vinegar  for  do- 
meftick  ufes. 

The  acid  obtained  by  thefe  procefles  Is  never  pure  ;  but  it 
may  be  purified  by  repeated  diftillations,  which  difengage  the 
ponderous  and  volatile  oil,  and  render  the  acid  as  clear  as  water. 
This  acid  when  rectified  by  this  procefs,  was  found  by  MefTrs. 
Arvidflbn  and  Oerhn  to  have  a  fpecifick  gravity  of  i.ooi  i  to  i. 

The  acid  of  ants  may  likewife  be  obtained  by  placing  linen 
cloths  impregnated  with  alkali  in  an  ant  hill.  From  thefe  the 
formiate  of  pot  afh,  of  foda,  and  ammoniack,  may  be  obtained 
by  lixiviation .  The  formick  acid  has  fome  refemblance  to  the 
acetous  acid  j  but  the  identity  of  thefe  two  acids  has  not  yet 
been  proved.  Mr.  Thouvenei  found  more  analogy  between  it 
and  the  phofphorick  acid  :  but  all  this  wants  proof. 

The  formick  acid  retains  water  with  fo  much  force,  that  it 
cannot  be  entirely  deprived  of  it  by  diftillation.  "When  it  is  ex- 
ceedingly pure,  its  fpecifick  gravity  is  to  that  of  water  as  1.0453 
to  I. 

It  affects  the  nofe  and  the  eyes  in  a  peculiar  manner,  which  is 
not  difagreeable.  Its  tafte  is  penetrating  and  burning  when 
pure,  but  agreeable  when  diluted  with  water. 

It   pofTciies  all  the  charafters  of  acids. 

When  boiled  with  the  fulphurick  acid,  it  turns  black  as  foon 
2S  the  mixture  is  heated.  White  penetrating  vapours  arife  ; 
and  when  it  boils  a  gas  is  emitted,  which  unites  difficultly  with 
diftilied  water,  or  with  lime  water.  The  formick  acid  is  decom- 
pofed  in  this  operation,  for  it  Is  obtained  in  lefs  quantity. 

The  nitrick  acid  diftilied  from  it,  deftroys  it  completely  ;  a 
gas  arifes  which  renders  lime  water  turbid,  and  is  difficultly  and 
fparingly  foluble  in  water. 

The  muriatlck  acid  only  mixes  with  it,  but  the  oxigenated 
niuriatick  acid  decompofes  it. 

Meffirs.  ArvidlTon  and  Oerhn  have  determined  the  affinities 
of  this  acid  with  various  bafes  in  the  following  order  :  barytes, 
potafh,  foda,  lime,  magnefia,  ammoniack,  zinc,  manganefe,  i- 
ron,  lead,  tin,  cobalt,  copper,  nickel,  bifmuth,  filver,  alumine, 
eflential  oils,  water. 

This  acid  mixes  perfectly  with  fplrit  of  wine.  It  unites  dif- 
ficultly with  the  fixed  oils,  and  with  the  volatile  oils,  by  the  af- 
fiftance  of  heat.  It  attacks  foot  ;  afiumes  a  fawn  colour  ;  and 
lets  fall  a  brown  fediment  as  it  cools,  which  by  diftillation  af- 
fords a  liquor  of  a  yellowifti  colour  and  a  difagreeable  fmell,  ac- 
compajiied  with  elaftick  vapours. 


Animal  FutrefaBkn^  5^5 

CHAPTER  XII. 

Concerning  Putrefaflion. 

EVERY  living  body,  when  once  deprived  of  life,  performs  a 
TCtroj^rade  procefs,  and  becomes  decompofed.  This  decompofi- 
tion  is  called  Fermentation  in  vegetables,  and  Putrefaction  in 
animal  fubftances.  The  fame  caufes,  the  fame  agents,  and  the 
fame  circumftances,  determine  and  favour  the  decompofition  of 
vegetables  and  animals,  and  the  difference  of  the  productions 
which  are  obtained  arifes  from  the  difference  of  the  conftituent 
parts  of  each. 

Air  is  the  principal  agent  of  animal  decompofition,  but  wa- 
ter and  heat  prodigioully  facilitate  its  action.  *<  Fermentatio 
ergo  definitur  quod  fitc  orporis  denfioris  rarcfaclio,  particular- 
umque  aerearum  interpofido  :  ex  quo  concluditur  debcre  in 
aere  fieri  nee  nimium  frigido,  ne  rarefa£l:io  impediatur  ;  nee 
nimium  calido,  ne  partes  raribiles  expellantur." — Becher,  Phyf. 
Sub.  lib.  i.  f.  5.  p.  313.  edit.  Francofurti. 

An  animal  fubftance  may  be  prcferved  from  putrefa6lion  by 
depriving  it  of  the  contact  of  air  ;  and  this  procefs  may  be  ac- 
celerated or, retarded  by  varying  or  modifying  the  purity  of  the 
fame  fluid. 

In  thofe  circumftances  wherein  we  fee  putrefa£lion  develop- 
ed without  the  contact  of  atmofpherical  air,  the  effecl  is  pro- 
duced by  the  water  which  impregnates  the  animal  fubftance, 
which  becomes  decompofed,  and  affords  the  element  and  \^iz 
a^ent  of  putrefaction.  Hence  no  doubt  it  arifes  that  putrefac- 
tion is  obferved  in  flefb  clofed  in  a  vacuum. — See  Lyons,  Ter- 
tamen  de  Putrefadtione. 

Moifture  is  likewife  an  indifpenfable  requifite  to  facilitate  pu- 
trefadion ;  and  any  fubftance  may  be  defended  from  this 
change  by  completely  drying  it.  This  was  performed  by  Villa- 
ris  and  Cazalet  of  Bordeaux,  by  means  of  (loves.  The  meat 
thus  prepared  was  preferved  for  feveral  years  without  having 
.contracted  any  bad  flavour.  The  fands  and  light  porous  earths 
prefcrve  the  bodies  of  men  only  by  virtue  of  the  property  of  ex- 
haufting  their  juices,  and  drying  the  folids.  From  this  caufe  it 
is  that  entire  caravans  have  been  difcovere-d  in  Arabia,  confift- 
ing  of  men  and  camels  perfectly  preferved  in  the  fands  under 
which  the  impetuous  winds  have  buried  them.  In  the  library 
of  Trinity  College  of  Cambridge,  in  England,  a  human  body 
may  be  feen  perfecfUy  preferved,  which  was  found  under   the 


1^6  Anitnal  PutrefaM'ton. 

fand  in  the  ifland  of  Teneriffc.  Too  much  humidity  impedes 
putrefad^ion,  according  to  the  obfervatibn  of  the  celebrated 
Becher  :  "  Nimia  quoque  humiditas  a  putrefa£lione  impedit, 
prout  nimius  calor  ;  nam  corpora  in  aqua  potius  gradatim  con- 
fumi  quam  putrefcere,  fi  nova  femper  affluene  fit,  experientia 
docet :  unde  longo  tempore  Integra  interdum  fubmerfa  prorfus 
a  putrefa£lione  immunia  vidimus  ;  adeo  ut  nobis  aliquando 
fpeculatio  occurreret  tra6lando,  tali  modo  cadavera  anatomise 
fubjiciendo,  quo  diutius  a  foetore  et  putrefa£lione  immunia  fo- 
rent."     Phyf.  Sub.  lib.  i.  f.  5.  cap.  i.  p.  277. 

In  order  therefore  that  a  body  may  putrefy,  it  is  necefiary 
that  it  fhould  be  impregnated  w^ith  water,  but  not  that  it  fhould 
be  inundated.  It  is  likewife  neceflary  that  this  water  fhould 
remain  in  the  texture  of  the  animal  body,  without  being  renew- 
ed. This  condition  is  requifite — i.  To  diflblve  the  lymph,  and 
to  prefent  to  the  air  the  mod  putrefcible  fubftance  with  the 
greateft  extent  of  furface.  2.  In  order  that  the  water  may  itfelf 
become  decompofed,  and  by  this  means  afford  the  putrefa£live 
principle.  Putrefadion  is  retarded  and  fufpended  by  baking, 
becaufe  the  flefh  is  dried,  and  by  that  means  deprived  of  the 
humidity,  which  is  one  of  the  moft  a<Slive  principles  of  its  de- 
compofition. 

A  moderate  degree  of  heat  is  likewife  a  condition  favourable 
to  the  animal  decompofition.  By  this  heat  the  affinity  of  aggre- 
gation between  the  parts  is  weakened,  and  confequentiy  they 
afTume  a  ftronger  tendency  to  new  combinations.  Hence  it  a- 
rifes  that  flefh  meat  keeps  longer  during  the  winter  than  the 
fummer,  and  better  in  cold  than  in  hot  countries.  Becher  has 
given  a  very  intelligent  fketch  of  the  influence  of  temperature  on 
animal  putrefaction  :    "  Aer   calidus  et  humidus  maxime   ad 

putrefaSionem  facit corpora  frigida  et  ficca  difficul- 

ter,  imo  aliqua  prorfus  non  putrefcunt,  quse  ab  imperitis  prolnde 
pro  fanctis  habita  fuere  ;  ita  aer  frigidus  et  ficcus,  imprimis  cal- 
idus et  ficcus,  aputrefaftione  quoque  prefervat ;  quod  in  Hif- 
pania  videmus,  et  locis  aliis  calidis,  ficco,  calido  acre  prsiditus, 
ubi  corpora  non  putrefcunt  et  refolvantur  ;  nam  cadavera  in 
oriente  in  arena,  imo  apud  nos  arte  in  furnis,  ficcari,  et  fic  ad 
finem  mundi  ufque  a  putredine  prgsfervari,  certum  efl :  inten- 
fum  quoque  frigusa  putredine  prsefervare  ;  unde  corpora  Stock- 
Jiolmi^  tota  hyeme  in  patibulo  fufpenfa  fine  putredine  animad- 
vertimus."     Phyf.  Sub.  1.  i.  cap.  i. 

Such  are  the  caufes  which  are  capable  of  determining  and  fa- 
vouring putrefadlion  ;  and  hence  we  may  perceive  the  befl 
means  of  preventing,  increafing,  or  modifying  it  at  pleafure. 
A  body  will  be   preferved  from  putrefa(ftion  by  depriving  it  of 


Animal  PutrefaHim.  cgf 

tlie  cental  of  atmofpherical  air  :  for  this  purpofe  nothing  more 
is  required  than  to  place  the  body  in  a  vacuum,  or  to  envelope 
it  in  a  covering  which  may  defend  it  from  the  immediate  adlioi^ 
of  the  air ;  or  elfe  to  envelope  it  in  an  atmofphere  of  fome  gaf-. 
eous  fubftance  which  does  not  contain  vital  air.  We  fhall  ob- 
ferve,  on  this  fubje6l,  that  the  effeds  obferved  in  flefli  expofed 
in  tlie  carbonick  acid,  nitrogene  gas,  Sec.  are  referable  to  a 
fimilar  caufe  j  and  it  appears  to  me  that  it  is  without  fufficient 
proof  that  a  conclufion  has  been  drawn,  that  thefe  fame  gafej, 
internally  taken,  ought  to  be  confidered  as  antifeptick  ;  becaufe, 
in  the  cafes  we  have  mentioned,  they  aft  only  by  defending  the 
bodies  they  furround  from  the  contact  of  vital  air,  which  is  the 
principle  of  putrefaftion.  Putrefaftjon  may  be  favoured  by 
keeping  bodies  at  a  fuitable  temperature.  A  degree  of  heat  from 
fifteen  to  twenty-five  degrees  diminilhes  the  adhefion  of  the 
parts,  and  favours  the  aclion  of  the  air  :  but  if  the  heat  be  great- 
er it  volatilizes  the  aqueous  principle,  dries  the  folids,  and  re- 
tards the  putrefa6lion.  It  is  neceiTary,  therefore,  for  the  de- 
compofition  of  an  animal — i.  That  it  have  the  contacl:  of  at- 
mofpherick  air  ;  and  the  purer  this  air  is,  the  more  fpeedy  will 
be  the  putrefadion.  2.  That  it  be  expofed  to  a  moderate  dcr 
gree  of  heat.  3.  That  its  texture  be  impregnated  with  humidi- 
ty.— The  experiments  of  Pringle,  Macbride,  Gardane,  have  like- 
wife  {hewn  us,  that  putrefaction  may  be  haftened  by  fprinkling 
the  anim,al  fubftances  with  water  containing  a  fmall  quantity  of 
fait  ;  and  it  is  to  a  like  c?ufe  that  we  ought  to  refer  feveral  pro- 
ceiTes  ufed  in  kitchens  to  produce  this  effect  in  food,  as  well  as 
in  the  preparation  of  cheefe,  the  curing  of  tobacco,  the  making 
of  bread,  &c. 

Becher  expreffes  himfeif  as  follows  on  the  caufes  which  pro- 
duce putrefa6lion  in  living  bodies  : — *'  Caufa  putrefaftionis  pri- 
maria  defeftus  fpiritus  vitalis  balGimini  e(l ;  Secundaria,  deinde, 
aer  externus  ambicus,  qui  interdum  adeo  putrefaciens  et  humi- 
dus-calidus  eft,  ut  fuperftitum  in  vivis  etiam  cornoribus  balfam- 
inum,  fpiritum  vincat,  nifi  confortando  augeatur  ;  ex  quo  coU 
hgi  poteit,  prefervantia  a  putiedme  fubtilia  ignca  oleofa  effe 
debere." — This  celebrated  chemiil  concludes;  from  tlie  fame 
principles,  that  ligatures,  copious  bleedings,  or  any  debilitation 
whatever,  determines  putrefaction.  He  likewife  thinks  that 
aftringents  oppofe  putrefaftion  only  by  condenHng  the  texture 
of  the  animal  parts  •,  for  he  confiders  rarefaction  or  relaxation 
as  the  firft  effeft  of  putrefadion.  He  thinks  that  fpirituous  li- 
quors a6l  as  antiputrefcent  merely  by  animating  and  ftimulating 
tlie  vis  vita:.  He  afhrms  that  the  ufe  of  faked  meats,  v»'hich 
heat  much,  aQliled  by  the  moifture  very  common  in  (hips  and 


S^)^  Animal  Putrefa5iion, 

fca*  ports,  produces  the  fcurvy;  and  he  obfcrves,  with  reafon, 
that  the  tendency  and  effect  of  putrefaftion  are  diametrically 
oppofite  to  thofe  of  generation  :  <«  nam  ficut  in  generatione 
partes  coagulantur  et  in  corpus  formantur,  ita  in  putrefadione 
partes  refolvuntur  et  quafi  informes  fiunt." 

As  the  phenomena  of  putrefa£tion  vary  according  to  the  na- 
ture of  the  fubftances  themfelves,  and  the  circumftances  which 
accompany  this  operation,  it  follows  that  it  muft  be  very  diffi- 
cult to  defcribe  all  the  phenomena  which  it  exhibits.  We  (hall 
therefore  endeavour  to  trace  only  thofe  which  appear  to  be  the 
mod  conftant. 

Every  animal  fubftance  expofed  to  the  air  at  a  temperature 
above  ten  degrees  of  Reaumur,  and  moiflened  with  its  own  fe- 
rdus  humour,  putrefies  ;  and  the  progrefs  of  this  alteration  ap- 
pears in  the  following  order. 

The  colour  firft  becomes  pale;  its  confiflence  diminifhes  j 
its  texture  becomes  relaxed  ;  the  peculiar  fmell  of  frefh  meat 
d-ifappears,  and  is  fucceeded  by  a  faint  and  difagreeable  fmell. 
The  colour  itfelf  at  this  time  inclines  to  blue  ;  as  we  fee  in 
game  which  begins  to  turn,  in  wounds  which  fall  into  fuppura- 
tion,  in  the  various  parts  threatened  with  gangrene,  and  even  in 
that  putrefadion  of  the  curd  which  forms  cheefe.  Mod  of 
our  food  futfers  the  firft  degree  of  putrefadlion  before  we 
ufe  it. 

After  this  firft  period  the  animal  p^irts  become  more  and 
more  foftent^d,  the  fmell  becomes  fetid,  and  the  colour  of.  an 
©blcure  brown  ;  the  fibrous  part  eafily  breaks  ;  the  texture  be- 
comes dry,  if  the  putrefaftion  be  carried  on  in  the  open  air ; 
but  the  furface  becomes  covered  with  fmall  drops  of  fluid,  if  the 
aecompofition  be  made  in  veffels   which  oppofe  its  evaporation. 

To  this  period  fucceeds  that  which  moll  minutely  chara61:er. 
izes  animal  putrefa£lion.  The  putrid  and  nauieous  fmell 
which  was  manifefted  in  the  fecond  degree,  becomes  mixed  with 
a  fmell  of  a  more  penetrating  kind,  arifing  from  the  difengage- 
ment  of  ammoniacal  gas  :  the  mafs  becomes  iliil  lefs  and  lefs 
confiftent. 

The  laft  degree  of  decompofition  has  it^  peculiar  chara<fters. 
The  fmell  becomes  faint,  naufeous,  and  exceedingly  acSlive. 
This,  more  efpecially,  is  contagious,  and  tranfnaits  the  feeds  of 
of  infedlion  ^  a  great  diftauce  :  it  is  a  true  ferment,  which  de- 
pofites  itfelf  upon  certain  bodies,  to  appear  again  at  long  inter- 
vals. Van  Swieten  reports,  that  the  plague  having  appeared  at 
Vienna  in  1677,  and  having  again  appeared  in  I7i3,the  houfes 
which  had  been  infe(fted  at  its  firft  appearancs  were  likewife 
infed.ed   at  the    fecond.     Van   Helmont  afferts  that  a  womaii 


Animal  PutrefaBion.  ^(^m 

contra<^cd  an  anthrax  at  the  extremity  of  Jier  fingers,  in  confe- 
quence  of  having  touched  papers  impregnated  with  peftilential 
virus.  Alexander  Benedi6tus  has  written  that  pillows  repro- 
duced the  contagion  feven  years  after  having  been  infedled  ; 
that  cords  had  remained  infected  for  thirty  years,  and  like  wife 
communicated  it,  according  to  Foreitus.  The  plague  at  MefTma 
was  for  a  long  time  concentrated  in  the  warelioufes  where  mer- 
chandize was  enclofed  with  fufpe^led  bales.  Mead  has  tranf- 
mitted  the  moft  alarming  h€ts  concerning  the  durable  impref- 
iion  of  contagion. 

When  the  putrefying  fubftance  is  in  its  laft  ftage,  the  fibrous 
texture  is  fcarcely  difcernable,  and  has  no  longer  any  appearance 
but  that  of  a  foft,  diforganized  and  putrid  mafs.  Bubbles  are 
feen  to  efcape  from  the  furface  of  this  matter  ;  and  the  whole 
ends  by  its  drying,  and  becoming  reduced  to  an  earthy  matter, 
which  is  friable  when  taken  between  the  fingers. 

We  do  not  fpeak  of  the  produdlion  of  worms  ;  becaufe  it 
appears  to  be  proved  that  they  owe  their  origin  only  to  the  flies 
which  endeavour  to  depofitc  their  eggs  upon  fuch  bodies  as  arc 
bed  fuited  to  fupport  the  young  they  contain.  If  flefli  meat  be 
well  wafhed,  and  left  to  putrefy  under  a  fieve,  it  will  pafs  through 
all  the  degrees  of  putrefacSlion  without  the  appearance  of  worms. 
It  has  been  obferved  that  worms  are  of  a  different  fpecies,  ac- 
xording  to  the  nature  of  the  difeafe^  and  the  kind  of  animal 
which  putrefies.  The  exhalation  which  arifes  from  bodies,  in 
thefe  different  cafes,  attraifls  different  fpecies  of  infefts,  accord- 
ing to  its  nature.  The  opinion  of  thofe  who  believe  in  fponta- 
neous  generation,  appears  to  me  to  be  contrary  to  the  experi- 
ence and  wifdom  of  nature,  which  cannot  have  committed  the 
reprodu(5lion  and  number  of  the  fpecies  to  chance.  The  pro- 
grefs  of  nature  is  the  fame  for  all  the  claffes  of  individuals  ;  and 
finqe  it  is  proved  that  all  the  known  fpecies  are  re-produced  in 
one  and  the  fame  manner,  how  can  we  fuppofe  that  nature  de- 
parts from  her  plain  and  general  laws  for  the  fmall  number  of 
individuals  whofe  generation  is  lefs  known  to  us  ? 

Becher  had  the  courage  to  make  obfervations,  during  the 
courfe  of  a  year,  upon  the  decompofition  of  a  carcafe  in  the  open 
air  ;  and  to  obferve  all  the  phenomena.  The  firft  vapour  which 
rifes,  fays  he,  is  fubtile  and  naufeous  :  fome  days  after,  it  has  a 
certain  four  and  penetrating  fmell.  After  the  firft  weeks,  the 
(kin  becomes  covered  with  a  down,  and  appeal's  yellowifti  ; 
greeniOi  fpots  are  formed  in  various  places,  which  afterwards 
become  livid  and  black  ;  a  thick  moffy  or  mouldy  fubftance  then 
covers  the  greatelt  part  of  the  body  j  the  fpots  open,  and  emit 
a  fanies. 


^d  Animal  Ptttrefa&ion, 

Catcafes  buried  \%  the  earth  prefent  very  diifer^ftt  {iheriofne- 
tia  ;  the  decompofition  in  a  burying  ground  is  at  leafl:  four  times 
as  flow.  It  is  not  perfedly  ended,  according  to  Mr.  Petit,  till 
three  years  after  the  body  has  been  interred,  at  the  depth  of  four 
feet ;  and  it  is  flower  in  proportion  as  the  body  is  buried  at  a 
greater  depth.  Thefe  fa6ts  agree  with  the  principles  which  we 
have  already  eflablifhed  for  bodies  buried  in  the  earth,  and  fub- 
je£led  to  laws  of  decompofition  very  different  from  thofe  which 
take  place  in  bodies  expofed  to  the  open  air.  In  this  cafe  the 
decompofition  is  favoured  by  the  waters  which  filter  through 
the  earth,  and  diflblve  and  carry  with  them  the  animal  juices. 
It  is  alfo  favoured  by  the  earth,  which  abforbs  the  juices  with 
1*iore  or  lefs  facility.  Meffrs.  Lemery,  Geoffroy,  and  Hunaud 
h&ve  proved  that  argillaceous  earths  exert  a  very  flow  a£l:ion  upon 
bodies  ;  but  when  the  earths  are  porous  and  light,  the  bodies 
then  dry  very  fpeedily.  The  feveral  principles  of  bodies  abforb- 
ed  by  the  earth,  or  carried  by  the  vapours,  are  difperfed  through 
ji  great  fpace,  imbibed  by  the  roots  of  vegetables,  and  gradually 
decompofed.  This  is  what  pafles  in  burying  grounds  in  thfe 
open  air  ;  but  it  is  very  far  from  being  applicable  to  the  fepul- 
chres  which  are  made  in  churches  and  covered  places.  Here 
is  neither  water  nor  vegetation  ;  and  confequently  no  caufe 
which  can  carry  away,  diflblve,  or  change  the  nature  of  the  ani- 
>inal  fluids  :  and  I  cannot  but  applaud  the  wifdom  of  govern- 
ment, which  has  prohibited  the  burying  in  churches  j  a  praiElice 
ti-'hich  was  once  a  fubje£l  of  horrour  and  infetlion. 

The  accidents  which  have  happened  at  the  opening  of  graves 
and  vaults  are  but  too  numerous,  to  render  any  apology  necef- 
fary  for  our  fpeaking  a  few  words  refpectirtg  the  method  of  pre- 
venting them. 

The  decompofition  of  a  body  in  the  bowels  of  tlie  earth  cait 
never  be  dangerous,  provided  it  be  buried  at  a  fufficient  depth, 
and  that  the  grave  be  not  opened  before  its  entire  and  complete 
decompofition.  The  depth  of  the  grave  ought  be  fuch  that  the 
external  air  cannot  penetrate  it  ;  that  the  juices  with  whicfh 
the  earth  is  impregnated  may  not  be  conveyed  to  its  furface  ; 
and  that  the  exhalations,  vapours,  or  gafes,  which  are  develop- 
ed or  formed  by  decompofition,  fliould  not  be  capable  of  forcing 
the  earthy  covering  which  detains  them.  The  nature  of  the 
earth  in  which  the  grave  is  dug,  influences  all  its  effe£ls.  If  the 
ftratum  which  covers  the  body  be  argillaceous,  the  depth  of  the 
grave  may  be  lefs,  as  this  earth  difficultly  aflbrds  a  pafl^age  to 
gas  and  vapour ;  but  in  general  it  is  admitted  to  be  neceflary 
that  bodies  (houid  be  buried  at  the  depth  of  five -feet,  to  preverit 
all  thefe  unhappy  accidents.     It  is  likewife  neceflary  to  attend 


Mineral  Waters.  60 1 

to  the  cifcumftance,  that  a  grave  ought  not  to  be  opened  before 
the  complete  decompofition  of  the  body.  This  decompofition, 
according  to  Mr.  Petit,  is  not  perfe£t  until  the  expiration  of 
three  years,  in  graves  of  four  feet  depth  j  or  four  years  when 
they  are  fix  feet  deep  This  term  affords  many  varieties,  ac- 
cording to  the  nature  of  the  earth,  and  the  conltitution 
of  the  fubjects  buried  in  it  -,  but  we  may  confider  it  as  a 
medium.  The  pernicious  cuftom  which  allows  a  fingle  grave 
to  families  more  or  lefs  numerous,  ought  therefore  to  be  fup- 
preffed  ;  for  in  this  cafe  the  fame  grave  may  be  opened  before 
the  time  prefcribed.  Thefe  are  abufes  which  ought  to  occupy 
the  attention  of  government  •,  and  it  is  time  that  the  vanity  of 
individuals  (hould  be  facrificed  to  the  publick  fafety.  It  is  like- 
wife  neceffary  to  prohibit  burying  in  vaults,  and  even  in  coffins. 
In  the  firft  cafe,  the  principles  of  the  bodies  are  fpread  into  the 
air,  and  infedt  it ;  in  the  fecond,  their  decompofition  is  ilowet 
and  lefs  perfect:. 

If  thefe  precautions  be  neglefled  ;  if  the  dead  bodies  be  heap- 
ed together  in  too  confined  a  fpace  ;  if  the  earth  be  not  proper 
to  abforb  the  juices,  and  decompofe  them  ;  if  the  grave  be  opened 
before  the  entire  decompofition  of  the  body — unhappy  accidents 
will,  no  doubt,  be  produced  j  and  thefe  accidents  are  but  too 
common  in  great  towns  where  every  wife  precaution  is  neglected. 
An  inftance  of  this  happened  when  the  ground  of  the  church  of 
St.  Benoit  at  Paris  was  dug  up  a  few  years  ago  ;  a  naufeous  va- 
pour was  emitted,  and  feveral  of  the  neighbours  were  affe£led 
by  it.  The  earth  which  was  taken  out  of  this  grave  was  un6lu- 
ous,  vifcid,  and  emitted  an  infedlious  fmell.  Meffrs.  Maret  and 
Navier  have  left  us  feveral  fimilar  obfervations. 


Concerning  Mineral  Waters. 

X  HE  name  of  Mineral  Water  is  given  to  any  watct 
whatever  which  is  fufficiently  loaded  with  foreign  principles  to 
produce  an  effedl  upon  the  human  body,  different  from  that 
which  is  produced  by  the  waters  commonly  ufed  for  drink. 

Men,  doubtlefs,  were  not  long  in  attending  to  the  differences 
of  waters.  Our  anceftors  appear  even  to  have  been  more 
ftridtly  attentive  than  ourfelves  to  procure  wholefome  drink.  It 
was  almoft  always  the  nature  of  the  water  which  determined 
their  preference  in  the  fituation  of  towns,  the  choice  of  habita- 
4...E 


^oa  Mineral  IVaters, 

tioMr>,  and  confequently  the  union  of  citizens.  The  fmell,  the 
tade,  and  more  efpecially  tlie  effects  of  waters  upon  the  animal 
economy,  have  been  thought  fulhcient,  during  a  long  time,  to 
determine  their  nature.  We  may  fee  in  the  writings  of  Hip- 
pocrates, how  much  obfervation  and  genius  are  capable  of  per- 
forming in  fubje<fts  of  this  nature.  This  great  man,  of  whom  it 
would  afford  but  a  very  imperfect  idea  to  confider  him  merely 
as  the  Father  of  Medicine,  was  fo  well  acquainted  with  the  in- 
fluence of  water  upon  the  human  body,  that  he  affirms  that  the 
mere  quality  of  their  ufual  drink  is  capable  of  modifying  and 
producing  a  difference  between  men  ;  and  he  recommends  to 
young  phyficians  to  attend  more  particularly  to  tlie  nature  of  the 
waters  their  patients  ought  to  ufe.  We  fee  the  Romans,  who 
were  frequently  under  the  neceility  of  fettling  in  parchedclimates, 
fpared  no  exertions  to  procure  wholefome  water  to  their  colonies. 
The  famous:  aquedudi:  which  carried  the  water  of  Uzes  to  Nif- 
mes,  is  an  unequivocal  proof  of  this  ;  and  we  fhill  poffefs  feve- 
ral  mineral  fprings  at  which  they  formed  colonies  for  the  advan- 
t<-jge  of  the  baths. 

It  was  not  till  near  the  feventeenth  century  that  the  applica- 
tion of  chemical  methods  to  the  examination  of  waters  was  firft 
made.  We  are  indebted  to  the  prefent  revolution  of  chemiilry 
for  the  degree  of  perfection  to  which  this  analyiis  has  been  car- 
ried. 

The  analyfis  of  waters  appears  to  me  to  be  neceffary,  In 
order — 

1 .  That  we  may  not  make  ufe  of  any  water  for  drink  but  fuch 
as  is  wholefome. 

2.  That  we  may  become  acquainted  with  thofe  which  poffefs 
medicinal  virtues,  and  apply  them  to  the  ufes  to  which  they  are 
fuited. 

3.  To  appropriate  to  the  different  works  or  manufadlories 
that  kind  of  water  which  is  the  bell  calculated  for  their  refpec- 
tive  purpofes. 

4.  To  correal  impure  waters,  or  fuch  as  are  either  Impregnat- 
ed vv'ith  any  noxious  principle,  or  charged  with  any  fait. 

5.  To  imitate  the  known  mineral  waters,  in  all  places  and  at 
all  times. 

The  analyfis  of  mineral  waters  Is  one  of  the  mod  difEcult 
problems  of  chemidry.  In  order  to  make  a  perfe6"t  analyfis,  It 
is  neceffary  to  be  aware  of  all  the  diPcindHve  characters  of  the 
fubllances  which  may  l.^e  held  in  folution  in  any  water.  The 
operator  mud  be  acquainted  with  the  means  of  feparating  from 
an  almod  infenfible  refidue  the  different  fubdances  which  com- 
pofe  it.     He  mud  be  able  to  appreciate  the  nature  and  quantity 


Mineral  Waters ^  603 

of  the  produ£ls  "which  are  carried  off  by  evaporation  ;  ard  like- 
wife  to  ascertain  whether  certain  compounds  are  not  formed  by 
the  operations  of  his  analyfis,  while  others  may  be  decompofed. 

The  fubftances  contained  in  waters  are  held  either  in  fufpen- 
fibn  or  in  folution. 

I.  Thofe  fubftances  which  are  capable  of  being  fufpended  in 
waters  are,  clay,  filex  in  a  ft  ate  of  divifion,  calcareous  earth, 
magnefia,  &c. 

Thofe  which  are  foluble  are,  pure  air,  the  carbonick  acid,  pure 
or  compound  alkalis,  lime,  magnefia,  the  fulphates,  the  muriates, 
the  extractive  matter  of  plants,  hepatick  gas,  &c.  The  molt 
ancient,  the  moft  general,  and  the  moft  fimple  divifion  of  mine- 
ral waters,  is  that  which  diftinguiflies  them  into  cold  waters, 
and  hot  or  thermal  waters,  accordingly  as  their  temperature  is 
the  fame,  or  exceeds  that  of  common  water. 

A  divifion  founded  on  the  feveral  qualities  of  thefe  waters, 
will  arrange  them  in  four  claffes. 

I.  Acidulous  or  Gafeous  waters — Thefe  are  known  by  their 
penetrating  tafte  ;  the  facility  with  which  they  boil  ;  the  difen- 
gagement  of  bubbles  by  fimple  agitation,  or  even  by  nf#« 
ftanding  ;  the  property  of  reddening  the  tinfture  of  turnfole  ; 
the  precipitating  lime  water,  &c. 

They  are  either  cold  or  hot.  The  firft  are  thofe  of  Seltz,  of 
Chateldon,  of  Vals,  of  Perols,  &c.  The  fecond  are  thofe  of  Yi- 
chi,  of  Montd'or,  of  Chatelguyon,  &c. 

II.  Saline  Waters,  properly  fo  called. — Thefe  are  charadi^ler- 
ized  by  their  faline  tafte,  which  is  modified  according  to  the  na- 
ture of  the  falts  they  contain.  The  falts  moft  generally  found 
in  waters  are,  the  muriate  of  magnefia,  the  fulphates  of  foda, 
of  lime,  &c-  Our  waters  of  Balaruc,  of  Yeufet,  &c.  are  of  this 
nature. 

III.  Sulphureous  Waters. — Thefe'  waters  have  long  been 
confidered  as  holding  fulphur  in  folution.  Meffrs.  Venel  and 
Monnet  oppofed  this  aflertion.  Bergmann  has  proved  that  moft: 
of  thefe  waters  are  merely  impregnated  with  hepatick  gas.  It 
appears,  however,  that  there  are  fome  v/hich  hold  true  liver  of 
fulphur  in  folution,  fuch  as  thofe  of  Bareges  and  of  Cotteret  ; 
whereas  the  waters  of  Aix  la  Chapelle,  Montmorency,  &c.  arc 
of  the  nature  of  thofe  mentioned  by  Bergmann.  We  may,  with 
Mr.  de  Fourcroy,  call  the  firft  by  the  name  of  Hepatick  Wa- 
ters, and  the  latter  by  the  name  of  Hepatized  Waters. 

This  clafs  is  known  by  the  fmell  of  rotten  eggs  which  tliey 
emit. 

IV.  Martial  Waters. — Thefe  have  the  property  of  exhibit- 
ing  a  blue   colour  by  the   folution  of  prulSate  of  lime  :    tlxey 


6©4  Mineral  Watef*s. 

have  befides  a  very  evident  aftringent  tafle.  The  iron  ia  held 
in  folution  either  by  the  carbonick  or  the  ftilphurick  acid.  In 
the  firft  cafe  the  acid  is  either  in  excefs,  and  the  water  has  a 
penetrating  fubacid  tafle,  as  tJie  waters  of  Buflang,  Spa,  Pyr- 
mont,  Pougue,&c.  or  the  acid  is  not  in  excefs,  and  confequent- 
Jy  the  waters  are  not  acidulous  ;  fuch  are  the  waters  of  Forges, 
Conde,  Aumale,  &c.  Sometimes  the  iron  is  combined  with 
the  fulphurick  acid,  and  the  water  holds  in  folution  a  trueful- 
phate  of  iron.  Mr.  Opoix  admits  this  fait  in  the  waters  of  Pro- 
vins  ;  and  thofe  of  Rougnc  near  Alais  are  almolt  faturated  with 
it.  Mineral  waters  of  this  quality  are  frequently  found  in  the 
vicinity  of  ftrata  of  pyrites.  There  are  feveral  near  Amalou, 
and  in  the  diocefe  of  Uzes. 

There  are  fome  waters  which  may  be  placed  indifcrlminately 
in  feveral  of  the  clafles  Thus,  for  example,  there  are  faline  wa- 
ters which  may  be  confounded  with  gafeous  waters,  becaufe  air 
is  conftantly  difengaged  from  them.  The  waters  pfBalaruc 
are  of  this  kind. 

"We  do  not  comprehend  among  mineral  waters  thofe  which 
fu^^  gas  to  efcape  through  them,  without  communicating 
any  charafteriftick  property  ;  fuch  as  the  burning  fpring 
of  Dauphiny,  &c. 

When  tlie  nature  of  any  water  is  afcertained,  its  analyfis  may 
be  proceeded  upon  by  the  union  of  chemical  and  phyfical  means. 
I  call  thofe  methods  phyfical  which  are  ufed  to  afcertain  certain 
properties  of  water  without  decompofmg  them.  Thefe  meth- 
ods are,  for  the  moft  part,  fuch  as  may  be  carried  into  effect  at 
the  fpring  itfelf.  The  appearance,  the  fmell,  and  the  tafte  af^ 
ford  indications  by  no  means  to  be  neglected. 

The  limpidity  of  any  water  indicates  its  purity,  or  at  leaft 
the  accurate  folution  of  the  foreign  principles  it  may  contain  ; 
an  imperfe<ft  tranfparency  denotes  that  foreign  fubrtances  are 
fufpended.  Good  water  has  no  fmell  :  the  fmell  of  rotten  eggs 
denotes  liver  of  fulphur,  or  hepatick  gas  -,  a  fubtle  and  penetra- 
ting fmell  is  proper  to  acidulous  waters  ;  and  a  fetid  fmell 
chara£lerizes  ilagnant  waters. 

The  bitternefs  of  waters  in  general  depends  on  neutral  falts. 
Lime,  and  the  fulphates,  give  them  an  auftere  tafte. 

It  is  likewife  of  importance  to  afcertain  the  fpecifick  gravity 
of  the  water,  which  may  be  done  either  by  the  means  of  the  a- 
reometer,  or  by  the  comparifon  of  its.  weiglu  with  that  of  an  e- 
qual  volume  of  diftilled  water. 

The  degree  of  heat  muft  likewife  be  taken  by  means  of  a 
good  mercurial  thermometer.  Thermometers  ijiade  wi$^  the 
(pirlts  of  wine  ought  to  be  reje&d  v  bse^aufe  th^ ^  dilatatioh,  ^f*; 


Mineral  Water Sk  60  r 

tcr  the  thirty  fecond  degree  of  Reaumur,  is  extreme,  and  no 
longer  correfponds  with  the  temperature  of  the  water.  It  is 
interefting  to  calculate  the  time  which  the  water  requires  to  be- 
come cool,  in  comparifon  with  diililled  water  raifed  to  the  fame 
degree  of  temperature.  Notice  muft  like  wife  be  taken  wheth- 
ther  any  fubftance  exhales,  or  is  precipitated  by  the  cooling. 

The  obferver  ought  likewife  to  enquire  whether  rains,  dry 
feafons,  or  other  variations  of  the  atmofphere,  have  any  influence 
on  the  temperature  or  quantity  of  water  of  the  fpring.  If  thefe 
caufes  adl  upon  the  fpring,  its  virtue  cannot  but  vary  exceeding* 
ly.  This  is  the  caufe  why  certain  mineral  waters  are  more 
highly  charged  with^thefe  principles  in  one  year  than  in  another  $ 
and  hence  alfo  it  arifes  that  certain  waters  produce  wonderful 
effects  in  fome  years,  though  in  other  feafons  their  effe£ls  are  tri- 
fling. The  celebrated  De  Haen,  who  analyfed  for  fever al  fuc* 
ceffive  years  all  the  waters  in  the  neighbourhood  of  Vienna, 
never  found  them  to  contain  the  fame  principles  in  the  fame 
proportion.  It  would  therefore  be  an  interefting  circumftance> 
if,  at  the  time  of  taking  up  or  bottling  of  thefe  waters  a  fkilful 
phyfician  were  to  analyfe  them,  and  publidi  the  refult. 

After  thefe  preliryjinary  examinations  have  been  made  at  the 
fpring,  further  experiments  muft:  be  made  according  to  the  me- 
thods of  chemiftry.  Thefe  experiments  ought  to  be  performed 
at  the  fpring  itlelf  :  but  if  this  cannot  be  done,  new  bottles 
may  be  filled  with  the  water  ;  and,  after  clofing  them  very  ac- 
curately, they  may  be  earned  to  the  laboratory  of  the  chemift, 
who  muft  proceed  to  examine  them  by  re^agents,  and  by  the 
method  of  analyfis. 

I.  The  fubftances  contained  in  water  are  decompofed  by 
means  of  re-agents  •,  and  the  new  combinations  or  precipitates 
which  are  formed,  immediately  point  out  the  nature  of  the  prin- 
ciples contained  in  the  waters.  Tlie  nioft  eflicacious  and  the 
only  neceifary  re-agents  are  the  following  ; 

1.  Tindlure  of  turnfolc  becomes  red  by  its  mixture  with  a- 
cidulous  waters. 

2.  Prufliate  of  lime,  and  that  of  ferruginous  potafh  not  fat- 
yrated,  precipitate  the  iron  contained  in  a  mineral  water  of  a 
biue  colour. 

3.  The  very  concentrated  fulphurick  acid  decompofes  moft 
neutral  falls;  and  forms  with  their  bafes  faits  very  well  known, 
and  eaftly  diftinguifhed. 

4.  The  oxalick  acid,  or  acid  of  fugar,  difengages  lime  from 
all  its  combinations,  and  forms  with  it  an  infolublc  fait. 

The  oxalate  of  apimoniack  produces  a  more  fpeedy  effect  ^ 
for,  by  adding  a  few  cryftals  of  thiji  fait  to  water  charged  witk 


6o6  Mineral  Waters, 

liny  calcareous    fait,  an  infoluble  precipitate  is   inftantly  form- 
ed. 

5.  Ammoniack  or  volatile  alkali  affords  a  beautiful  blue  col- 
our with  the  folutions  of  copper.  When  this  alkali  is  very  pure, 
it  does  not  precipitate  the  calcareous  fait,  but  decompnfes  the 
magnefian  only.  In  order  to  have  it  in  a  highlv  cauftick  ftate, 
a  fyphon  may  be  plunged  in  the  mineral  water,  and  ammoni?;cal 
gas  or  alkaline  air  pafl'ed  through  it.  The  water  ought  to  be 
kept  from  the  contact  of  the  atmofphere,  which  otherwife  might 
occafion  a  precipitation  by  virtue  of  its  carbonick  acid. 

6.  Lime  water  precipitates  magnefra  ;  and  it  likewife  precip- 
itates the  iron  from  a  folution  of  iulphate  of  iron. 

7.  The  muriate  of  barytes  detects  the  fmalleft  particle  of  ful- 
phurick  falts,  by  the  regeneration  of  ponderous  fpar,  which  is 
infoluble,  and  falls  down 

8.  Alcohol  is  a  good  re-agent,  on  account  of  its  affinity  with 
water. 

The  nitrates  of  filver  and  of  mercury  may  likewife  be  employ- 
ed to  decompofe  fulphurick  or  munatick  falts. 

II.  Thefe  re-agents,  indeed,  point  out  the  nature  of  the  fub- 
ftances  contained  in  any  water  j  but  they  do  not  exhibit  their 
accurate  proportions.  For  this  purpofe  we  are  obliged  to  have 
re^ourfe  to  other  means. 

There  are  two  things  to  be  conGdered  in  the  analyfis  of  any 
water:   i.  The  volatile  principles.     2.     The  fixed  principles. 

I.  The  volatile  principles  are  carbonick  acid  gas  and  hepat- 
ick  gas.  The  proportion  of  carbonick  acid  may  be  afcertained 
by  various  proceffes.  The  firft,  which  has  been  ufed  by  Mr.  Ve- 
nd, confifts  in  half  fdling  a  bottle  with  the  gafeous  water,  intend- 
ed to  be  analyfed.  A  bladder  is  then  to  be  tied  upon  the  neck 
of  the  bottle,  and  the  water  agitated.  The  air  v^hich  is  difen- 
gaged  inflates  the  bladder  ;  and  by  that  indication  an  ellimate 
rnay  be  made  of  its  quantity.  This  procefs  is  not  accurate  ; 
becaufe  agitation  is  not  fulHcient  to  difengage  ihe  whole  of  the 
carbonick  acid.  Neither  is  the  evaporation  of  the  water  in  the 
pneumato-chemical  apparatus  much  more  exact  ;  becaufe  the 
water  which  rifes  with  the  air  combines  again  with  it,  and  the 
gafeous  product  confi'ls  only  of  a  part  of  the  gas  contained  in 
the  water.  The  precipitation  by  lime  v/ater  appears  to  me  to 
l>s  the  mod:  accurate  procefs.  Lime  water  is  poured  into  a  de- 
terminate quantity  of  the  water,  until  it  ceafes  to  caufe  any  pre- 
cijlitate.  This  precipitate  being  very  accurately  weighed,  ^-^ 
parts  of  the  whole  mult  be  deducted  for  the  proportion  in  which 
water  and  earth  enter  into  it ;  and  the  remainder  is  the  acid 
contained  in  this  carbonate  ©f  iirae. 


Mineral  Waters*  60.7 

Hepatick  gas  may  be  precipitated  by  the  very  concentrated 
nitrick  acid,  according  to  the  experiments  of  Bergmann. 

The  oxigenated  muriatick  acid  has  been  propofed  by  Scheele  ; 
and  Mr.  De  Fourcroy  has  pointed  out  the  fulphureous  acid,  the 
oxides  of  lead,  and  other  re-agents,  to  precipitate  the  fmall 
quantity  of  fulphur  held  in  folution  in  hepatick  gas. 

2.  Evaporation  is  commonly  ufed  to  afcertain  the  nature  of 
the  fixed  principles  contained  in  any  mineral  water.  Veilels  of 
earth  or  porcelain  are  the  only  kind  fuitablc  to  this  purpofe. 

The  evaporation  mud  be  moderate  ;  for  drong  ebullition  vol- 
atilizes fome  fubftances,  and  dccompofes  others.  In  proportion 
as  the  evaporation  proceeds,  precipitates  are  afforded,  which  Mr. 
Boulduc  propofes  to  take  out  as  they  are  formed.  The  cele- 
brated Bergmann  advifes  evaporation  to  drynefs,  and  to  analyfe 
the  refidue  in  the  following  manner  : 

1.  This  refidue  muft  be  put  into  a  fmall  phial,  and  (trong- 
ly  agitated  with  alcohol  -,  after  which  the  fluid  muil  be  filtrated. 

2.  Upon  the  refidue  pour  eight  times  its  weight  of  cold  dif- 
tilled  water  ;  agitate  this,  and  filter  the  fluid,  after  (landing 
feveral  hours. 

3.  Laftly,  the  refidue  muft  be  boiled  for  a  quarter  of  an  hour 
in  five  or  fix  hundred  parts  of  diililled  water,  which  fluid  muft 
be  feparated  by  filtration. 

4.  The  refidue,  which  is  neither  foluble  in  water  nor  in  al- 
cohol, mufl:  then  be  moiftened,  and  expofed  for  feveral  days  to 
the  fun  :  by  this  treatment,  the  iron  which  it  may  contain,  rufts. 
It  muft  then  be  digefied  in  diftilled  vinegar,  which  diflblves  lime 
and  magnefia  ;  and  this  folution,  evaporated  to  drynefs,  affords 
either  an  earthy  fait  in  filaments  which  are  not  deliquefcent,  or 
a  deliqucfcent  fait  5  which  laft  has  magnefia  for  its  bafe.  The 
infoluble  refidue  contains  iron  and  clay,  which  are  to  be  diifolv- 
ed  in  the  muriatick  acid.  The  iron  is  firft  to  be  precipitated  by 
the  prulfiate  of  lime  ;  and  afterwards  the  clay  by  another  alkali. 

The  falts  which  the  alcohol  has  difiblved,  are  the  muriates  of 
magnefia  and  of  lime.  They  are  eafily  known  by  decompofing 
them  by  the  fulphurick  acid. 

With  refpe(ft  to  the  falts  difiblved  in  the  cold  water,  they  mufl 
be  flowly  cryftallized  ;  and  their  form,  and  other  obvious  quali- 
ties, will  (hew  what  they  are. 

The  folution  by  boiling  water  contains  nothing  but  fulphate 
of  lime. 

When  the  analyfis  of  any  water  has  been  well  made,  the  fyj^ 
thefis  becomes  eafy  j  and  the  compofition  or  perfedl  imitatiow 
of  mineral  waters  is  no  longer  a  problem  infoluble  to  chemift?. 
AVhat,  in  fact,  is  a  mineral  water  .?  It  is  rain  water,  which,  fii- 


00  8  Mineral  Heaters. 

tcring  through  the  mountains,  becomes  impregnated  with  the 
various  foluble  principles  it  meets  with.  Why,  therefore,  when 
once  we  know  the  nature  of  thefe  principles,  can  it  not  be  polli- 
ble  to  diflblre  them  in  common  water,  and  to  do  that  which 
nature  itfelf  does  ?  Nature  is  inimitable  only  in  its  vital  opera- 
tions J  we  may  imitate  its  effedls  perfeftly  in  all  other  procelT- 
cs :  we  may  even  do  better  ;  for  we  can  at  pleafure  vary  the 
temperature  and  the  proportions  of  the  conftitiient  parts.  The 
machine  of  Nooth,  improved  by  Parker,  may  be  made  ufe  of  to 
compofe  any  gafeous  mineral  water,  whether  acidulous  or  hepat- 
ick  ;  and  nothing  is  more  eafy  than  to  imitate  fuch  waters  as 
contain  only  fixed  principles.    . 


FINX9. 


• 


INDEX. 


ACIDS 
Acid  acetous 
Acid  of  Amber 

Animal 

of  Benzoin 

of  Borax 

—  of  Camphor 

—  Carbonick 

Citrick 

of  Fat 

Fluorick 

Ladtick 

Malick 

of  Molybdena 

Muriatick 

Oxigenated         « 

—  Nitrick 

Nitro-muriatick 

.   Oxalick 

'     '    of  Phofphorus 
^  -•—  Pruflian 

Pyro-ligneous 

Pyro-mucilaginous 

of  S.  of  Milk 

'     ■'  Sulphurick 
—  of  Tartar 

of  Tungften 

Affinity  53  et  feq. 

Agate . 

Aggregation 

Air  atmofpherick 

Air  vital 

Alabafler 

Alchemifts 

Alcohol 

Alkalis 

Alkaline  Gas     » 

Aloes 

Alum 

Alumine  ^ 

Amalgam 

Amber 

Amianthus 

Animal  Subftances 

Antimony 


Page 
130 
536 
511 
59^ 
445 
169 
438 
133 
469 

555 
195 
165 
170 
407 
156 
158 
146 
167 
462 
5^2 
354 
468 
467 
546 
140 
534 
399 


Apparatus  Pneumatick 

Aqua  regia 

Arbor  Dianae 

Archil 

Aroma 

Arfenick 

Ammoniack 

Sal 


Afbeftos 
Afphaltes 
AfTa  Foetida 
Attra(5lion,  .?  i  et  feq. 
Aurum  Mufivum 
Azure 


^36 

53 
I09 

96 
185 
39* 
5*9 
iai>  473 
128 

449 
203 
180 
330 
5" 
215 
541 
^5 


B, 

Balances 

Balloon  air 

Balfams 

Bark  of  VegetabJes 

Barytes 

Balaltes 

Benzoin 

Beryl 

Bile 

Bifmuth 

Bleaching 

Blende 

Blood 

Borate  of  Ammoniack 

of  Potalh 

of  Soda 

Borax  and  its  acids  et  feq, 

Brandy 

Brewing 

Bronze 

Butter 


Cacholong 

Calcedony 

Caloriek 

Camphor 

Cantharides 

Caoutchouc 


I»age 

90 

16S 

4Sl 
497 
28i 
127 
165 
2L4 

510 

448 

330 

299 


5* 
94 
444 
4U 
178 
24  2 
445 
aa9 
557 
2gz 
161 
306 
105,551 

•  ^75 
171 
ibid 
169 
5»6 
S^S 
367 
550 


«37 
237 

508 
449 


INDEX, 


Page 

Page 

Carbone  . 

87  Fulminating  Silver 

383 

Carbonate  of  ammoniack 

139 

Pnlfl 

39<> 

. ofPotafti 

138 

Furnaces 

44,  etfeq. 

nf  ^n(\i 

139 

18a 

FulibleSpar 

»94 

Carnelian 

23^ 

G. 

CafTava 

455 

Galena 

316 

Caftoreum 

584 

Garnets 

a26 

Cat's  Eye 

a37 

Gafes 

90 

Charcoal 

56,  50a 

Gaftrick  Juice 

544 

Cheefe 

550 

Geology 
Girafol 

261 

Chemiflry 

43 

a37 

Chryfolite 

0,29 

Glafs 

24a 

Chryfoprafe 

244 

Gluten,  Vegetable 

457 

Cinnabar 

377 

Glue 

56* 

Clay 

50 

Gold 

3«4 

Cobalt 

aa8 

Gums 

426 

Copper 

358 

Gum  Guttae 

448 

Cream 

550 

Gun-powder 

154 

Crucibles 

48 

Gypfum 

J91 

Cryftal 

230 

Crtftallization58etfeq. 

H. 

D. 

Diamond 
Digeftion 
Diftilling 
Dying,  arts  of 

4 

Heat 

72,  et.feq. 

^58 

543 

47 

Hematites 
Hepatick  Stone 
Honey 
Horn-ftone 

210 
ibid 
486 

222 

475 

Hyacinth 

227 

E. 

Hydrogenous  Gas 

91 

Eagle  ftpne 

338 

Hydrophanes 

^38 

Earth 

175 

L 

l^arth,  Calcareous 

178 

Ponderous 

179 

Jafper 

5138 

. Magneiian 

180    Jelly 

561 

. Aluminous 

ibid   Jet 

517 

. Siliceoui* 

181 

1  Indigo 

478 

Egg.  , 
Elallick  Gum 

587 
449 

1  Iron 
!  liinglafs 

563 

Elements 

70 

Emerald 

aaS 

K. 

Ether 

530 

Kaolin 

219 

Ethiops  Martial 

376 

Kermes              ** 

591 

Evaporation 

46 

L. 

F. 

Fat 

554 

Labdanum 

444 

Fayence 

F£cula 
Mkd  Spar 
^^Pmentation 

218 
*       453 

Laboratory 

Lac 

Lapis  Lazuli 

Lapis  Infernalis 

43 
591 
245 
381 

Tire 
Elelh 

^l^t  feq. 

Lava 
Lead 

241 
316 

Elir.ts 

Eluate  of  Lime 

-.194 

Light 
Lime 

8a,  453 

178, 188 

Vior  Spar 

ibid 

Liquorice 

JOi 

INDEX. 


Page 

Lithology 

I75,etfeq. 

Luna  Cornea 

38Z 

Lutes 

49 

M. 

Magnefia 

180 

Magnefian  Salts 

aoi 

Magnet 

334 

Manganefe 

310 

Manna 

49^ 

Marble 

185 

Maltick 

443 

Mecca,  Balfam  of 

441 

Mercury 

368 

Mercurius  Dulcis 

375 

Metals 

370 

Mica 

220 

Milk 

54J 

Mines 

^n 

Molybdena 

404 

Montgolfier 

94 

Mortar 

190 

Mountain  Cork 

ai4 

Mucilage 

4aj 

Muriate  of  Ammoniack 

105 

1               1  nf  Pnfnfh 

T62 
ibid 
197 

of  Lime 

Mulk 

584 

N. 

Naphtha 

509 

Nickel 

291 

Nitrate  of  Ammoniack 

156 

nf  PfitnOi 

X  f  1* 

of  Sorfi 

*5* 

196 

108 

Nitrogene  Gas 

Nitro-muriatick  Acid 

167 

Nitrous  Gas 

141 

O. 

\ 

Oculus  Mundi 

238 

Oils 

A%1 

Olibanum 

449 

Opal 

a36 

Opium 

493 

Orpiment 

284 

Oxigenous  Gas 

96*  495 

Oxides 

-^2Z 

P. 

Perfumes 

498 

Petroleum 

^09 

Petrofilex 

Pewter 

Phofphate  of  Lime,  various 

Phofphorick  Glafs 

Phofphorus 

Pit  Coal 

Pitch 

Plafter  Stone 

Platina 

Plumbago 

Pollen 

Ponderous  Earth 

Porcelain 

Porphyry 

Pottery 

Pot  Stone 

Powder,  Fulminating 

Precipitate 

Pruflian  Blue 

Putrefadlion 

Pyrites 

Pyrometer  of  Wedgwood 


Quartz 


Realgar 

Receivers 

Refins 

Refpiration 

Retorts 

Ruby 


Sago 

Sandarach 

Sal  Ammoniack 

Salt,  common 

Salt  Petre 

Sapphire 

Scammony 

Schorles 

Selenite 

Serpentine 

Serum 

Sideritc 

Silex 

Silver 

Size 

Slate 

Smalt 

Soap 

Soap  StOBC 


R. 


Page 

3*9 
198 
576 
574 
#07 
44» 
191 
393 
339 
484 
179 
219 

355 
216 

ai3 

^SS 
56 

339 

5'2'h  595 

95 

75 


»34 


^4 

48 

44  r 

lot 

47 
aa6 


455 
443 
I65 
i6z 
163 
230 
448 
%AO 
191 
»I3 
SSi 
339 
181 
8 


433 


^f^ 


INDEX. 


Soli 

Page  551 

U. 

Pag6 

Soktioii 

63 

Ultramariac 

^5S 

Soup 

561 

Urine 

566 

Spar,  Ponderous 

198 

J  WW 

Spermaceti 

586 

V. 

Starch 

Steatites 

45  7 
3,1% 

Varnifh 

45^ 

Steel 

337 

Vegetables 

409 

Stone,  of  the  Bladder 

572 

Vermilion 

37? 

Sublimate,  Corrofive 

B74 

Veffels,  chem.  et  fe<5. 

44 

Sublimation 

^5!Vin«gar 

535 

Sugar 

459 

Violets,  Syrup  ot 

131 

Sulphate  of  Ammoniack 
■     ■       of  Potafh 

145 
X44 

Vital  Air 
Volcanick  Produ<5ls 

96 

a4« 

of  Soda 

ibid 

Voicanos 

5i» 

191 

Sulphur 

S4>  140 

W. 

Swine  Stone 

209 

Water,  its  compolition 

III,  4*8 

T. 

Waters,  Mineral 

60I 

Talc 

ftl2 

V/ax 

485 

Tartar 

533 

Wolfram 

401 

Tin 

324 

Wood 

415 

Tinning  of  Copper 

367 

Woulfe,  his  apparatus 

5» 

Topaz 

aa7 

Tourmalin 
Trapp 

•    »39          .'  .Jl^.           Z. 

a44            ^^- 

Trompe 

378   Zaffre 

489 

Tungften 

398    Zeolite 

22s 

Turnfole 

130 

Zinc 

$<^.s 

f